Green Car Congress: Toyota Takes A Swipe at GMs E-Flex

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Toyota Takes A Swipe at GM’s E-Flex

4 September 2007

Toyota’s view of E-Flex (the EV-based PHV) series-hybrid approach versus Toyota’s PHEV approach. Click to enlarge. Source: Toyota

Toyota Motor Corporation (TMC) is positioning its emerging approach to plug-in hybrid vehicles—based on augmenting the battery pack of a conventional hybrid and altering the operating strategy (earlier post)—as an approach superior to that of the series-hybrid architecture of GM’s E-Flex systems (earlier post), as represented by the different versions of the Chevy Volt.

The rationale, outlined by Toyota Executive Vice President Kazuo Okamoto in a presentation about the company’s technology strategies to investors in Tokyo on 3 Sep, is that once current parameters such as driving range, required battery size and charge time are factored in, the augmentation of the existing parallel-hybrid platform makes the most sense.

Toyota’s view of the plug-in. Click to enlarge.

The prototype Toyota plug-in is based on a Prius with a 2.6kWh NiMH battery pack supporting an all-electric range of 13 km (8 miles). The gasoline (flex-fuel) version of the Chevy Volt, targeted for production in 2010, is spec’d to have a 16kWh li-ion battery pack that supports a 40-mile all-electric range.

The presentation, Challenges for Sustainable Mobility, outlined a number of Toyota technology efforts including advanced gasoline and diesel engine work and alternative fuels (biofuels, hydrogen and electricity).

The investor presentation followed Toyota’s announcement in July that it has developed a plug-in hybrid vehicle and had become the first manufacturer to have such a vehicle certified for use on public roads in Japan.

Toyota will conduct public-road tests in Japan with eight units of the Plug-in HV to verify electric-motor-only cruising ranges and optimal battery capacity. While doing so, it plans to provide the government with data for formulating testing methods for emissions and fuel efficiency and to consider TMC’s measures for promoting plug-in hybrids and the use of electricity.

In addition, Toyota is also providing plug-in hybrid prototypes to the Advanced Power and Energy Program at the University of California, Irvine (UCI) and the Institute of Transportation Studies at the University of California, Berkeley (UCB), as part of its on-going sustainable mobility development program with the two UC campuses. (Earlier post.)

Toyota and French utility EDF reportedly will announce an agreement this week to develop recharging points to serve the plug-in hybrid cars Toyota plans to roll out in a few years’ time. (Earlier post.)

Specifications of Toyota Plug-in HV
Vehicle	Length/Width/Height	4,445/1,725/1,490 mm
	Weight	1,360 kg
	Seating capacity	5 persons
All-electric performance	Cruising range	13 km in 10-15 cycle
All-electric performance	Max. speed	100 km/h
Engine	Displacement	1,496cc
	Max. output	56 kW (75 hp) @ 5,000rpm
	Max. torque	110 Nm (81 lb-ft) @ 4,000 rpm
Motor	Type	AC synchronous
	Max. output	50 kW (67 hp) @ 1,200 - 1,540rpm
	Max. torque	400 Nm (295 lb-ft) @ 0-1,200 rpm
Secondary battery	Type	NiMH
	Capacity	13 Ah (6.5 Ah x 2)
	Rated voltage	202V
Overall System	Maximum Output	100 kW (134 hp)
Overall System	Voltage	202 - 500V
Battery charging	Power source	Household electrical power
Battery charging	Charging time	1 - 1.5 hrs (200V); 3 - 4 hrs (100V)

Toyota has already expressed concerns on the record about after-market conversions of existing hybrids to plug-in hybrids. (Earlier post.)

Also, at the recent 2007 Management Briefing Seminars in Traverse City, Michigan, Toyota told the audience that a number of serious hurdles stand in the way of getting plug-in hybrids on the road, and that even if the vehicles do make it to market, a battery-powered plug-in may be no more efficient in reducing carbon dioxide emissions than the current charge-sustaining gas-electric hybrids on the road today. (Earlier post.)

In August, reports contended that Toyota was going to delay its deployment of lithium-ion batteries in high electric-mileage hybrids because of safety concerns with its batteries, which use cobalt oxide cathode materials. (Earlier post.)

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Surprising that Toyota was that far out in front on hybrids last year, and is now this far behind on models for a few years down the road. I don't think they realize just how important the Volt's all electric range advantage is. Most of us will only be putting gas in our Volts every other month or so, and the equivalent of a gallon of gasoline in electricity costs about 70 cents, not $3. Plus, I can get a wind generator and charge a bank of lead acid batteries for next to nothing...
I am betting that GM screws this up, I hate to be a pessimist, but Detroit just doesn't have a recent history of brilliance in design and/or vision.

Posted by: Ziv | Sep 4, 2007 11:33:02 AM

Unless Toyota knows something, I don't know, I would think that the decided advantage is to the car with the larger battery, smaller ICE, and less complicated drive line. I still believe a BEV, with a microcomputer controlled portable generator, perhaps on a trailer, as a range extender for long trips (600miles), would fit most of our drive cycles, especially if there is an abundance of charge stations along the way to help offset the liquid fuel usage. For short to medium distances, the generator and its weight and drag wouldn't be needed. Think about how much lighter the car would be and how much more space would be available without the need of the inefficient ICE and its associated drive mechanics.

Posted by: Lad | Sep 4, 2007 11:38:09 AM

Ziv@

Here is a link with more information on the Volt from GM and Li Ion bateries. http://www.autolinedetroit.tv

Posted by: Lad | Sep 4, 2007 11:44:21 AM

If everyone started driving around with little trailers we would have to redo all the parking lots in the US.

Posted by: Brian | Sep 4, 2007 11:48:20 AM

The article started out positive, then drifted downward.

On the comparison chart, the E-Flex side appears less complex to me as well. Yes, it’s a bigger battery, but, then, it also provides more electric miles.

The other thing is, the E-Flex Volt side has released a production target date of 2010. That’s pretty far away for me, but it’s better than just talking about how the batteries aren’t ready yet.

By the way, I'm counting on the Volt not being screwed up, as GM knows they need a win here, and I'm anxiously waiting to test drive one.

Posted by: George K | Sep 4, 2007 11:52:40 AM

This is very puzzling, to say the least, and Toyota is making a very big bet on longer than necessary odds. I can't figure out why they seem to be so anti-series hybrid. Could it be that they've convinced themselves that consumers won't buy them? If that's it, I'm convinced they're wrong, and the market will change their mind in due time, the hard way.

Posted by: Lou Grinzo | Sep 4, 2007 12:01:51 PM

@ Ziv -

I'd be careful about claiming that Toyota will be playing catch-up with GM on plug-in hybrids for a number of years. The regular Prius is shipping today whereas the Volt is vaporware. An affordable vehicle with a 16kWh Li-ion battery pack is a tall order.

The Japanese always prefer incremental improvement over revolutionary changes, because the engineering risk is much lower. That said, Toyota's preferred battery manufacturer, Panasonic, hasn't come up with sufficiently safe Li-ion batteries yet so they have to keep using proven NiMH technology and spin that as a good thing. In practical terms, though, an 8 mile range on grid electricity is too little to be worthwhile. You'll almost always have to fire up the ICE at some point during your trip and, heating the block and oil guzzles gas.

The external socket is still useful if it can be used in reverse to run your home during a power outage or, for running mobile electrical equipment where there is no grid access (e.g. lights on a camping trip, power tools when clearing brush on your land etc.) However, you don't really need a secondary battery for that. If you leave the key in the ignition, the engine should just fire up if your plug-out power demand can no longer be met by the battery without reducing its life expectancy.

What is true is that Toyota's compound hybrid transmission is a more efficient drivetrain than GM's purely serial hybrid with battery buffer can ever hope to be. The genset will be running efficiently but that won't fully compensate for the high drivetrain losses. Ergo, once you get beyond the range covered by grid electricity, the Volt will actually be a wee bit of a gas hog.

Posted by: Rafael Seidl | Sep 4, 2007 12:11:53 PM

@ Ziv -

Posted by: Rafael Seidl | Sep 4, 2007 12:20:46 PM

GM Volt or Prius Plugin. Neither of these are in production yet, so can we really say which one is better.

I think that when we can compare 2 real cars side by side that will be a really fun comparison, until then.....

It will be interesting to see who wins this race, right now all we are doing is playing "what if".
KJD

Posted by: KJD | Sep 4, 2007 12:34:37 PM

Lad, thanks for the link, I think Lutz said a lot of interesting things but the one that stood out the most to me is that he said they would build it on time if there were no unforseen problems, or words to that effect. It just seems like he would be more guardedly optimistic, and would be stressing the game changing nature of the switch to primarily electric energy more, if GM really thinks they can pull this off within 3 years.
Rafael, I think I understand what you are saying about Toyota having the Prius in hand, and the Volt is still in the bush, but Toyota doesn't seem to be building/designing anything that would compete with the Volt in a meaningful way. Unless they spring something in Frankfort, it sounds like they are not going to be making a real Plugin vehicle in the next few years. 8 miles range or 10, or 12, just don't mean anything. If GM can build a car with an electric only range of 40 miles, it won't matter that the Prius gets 70mpg and the Volt gets 'only' 50mpg after the first 40 miles when the range extender kicks in, because it won't happen frequently enough for the Volt be using much gasoline, anyway.
Finally, Lutz has stated that they will have a functioning prototype early next year, so if GM can put the car on the road in some form within a few months, maybe they actually will sell 60,000 of them in 2010 as Bloomberg claims they are working towards.
I have to admit that I am incredibly biased, I really want the Volt to work and my enthusiasm for it has me both more optimistic and pessimistic at the same time. If they build this type of car it could change the world in a relatively short period of time. We have a world economy based on cheap oil, which is now not so cheap, supplied increasingly by nations that we really shouldn't be enriching, i.e. Saudi Arabia, Russia, Venezuela, Iran... If the automotive portion of the global oil demand began to decline as cars increasingly use electricity instead of gasoline, the impact would be huge, and it wouldn't take long for the changes to be felt.
We are at or near peak oil production, and the only thing that can stave off relatively rapid rises in oil prices is a reduction in demand. We can't increase supply so we need, absolutely, to reduce demand.

Posted by: Ziv | Sep 4, 2007 12:36:22 PM

Forgot the Bloomberg article about the prototype and the goal of building 60,000 in 2010...
http://www.bloomberg.com/apps/news?pid=20601103&sid=atR4ArJR__OI

Posted by: z | Sep 4, 2007 12:38:01 PM

I would expect that GM is doing their typical boast and botch approach. You can get 40 miles all electric on a prius today by reprogramming it, but it will definately cause battery pack replacement much, much sooner. the deeper you draw the less life they have. Chevy can assume the battery tech will be much better by then, or maybe they are expecting the Volt to be like the Vega, a disposable car that people wont mind tossing in three years when the battery is toast.

Posted by: Fred | Sep 4, 2007 12:38:03 PM

George,

Good point. The simplicity of the Volt means less that can go wrong. I hope Toyota eats its words...for once.

Posted by: dave | Sep 4, 2007 12:45:56 PM

The rationale, outlined by Toyota Executive Vice President Kazuo Okamoto in a presentation on the company’s technology strategies to investors in Tokyo on 3 Sep [...]

Toyota investors have been hearing about the Volt for a while now, and likely want to know why GM appears to be stealing a march on them. Toyota needs to downplay the Volt as much as possible to keep the investors quiet while (a) hoping the Volt fails, and (b) kicking their engineering into high gear to beat it. The fact that they're pushing their 8-mile Prius as a better solution suggests that GM may have caught them with their pants down.

Posted by: Matthew | Sep 4, 2007 12:53:40 PM

AER -- how do they measure this? Toyota is upfront about 13 km on the Japanese 10-15, how is the GM 40 miles AER calculated? A comparison is meaningless unless you use the same basis for comparison.

Posted by: cidi | Sep 4, 2007 1:00:37 PM

The series is a better approach it seems.

I wonder if Toyota simply doesn't want to ditch technology that they have a significant investment and lead in?

Either way, GM has a lot to prove. I question people saying it's total vaporware. GM can't afford not to release this car, it's the best PR they've had in years.

Posted by: CTE | Sep 4, 2007 1:24:00 PM

Fred :
"You can get 40 miles all electric on a prius today by reprogramming it, but it will definately cause battery pack replacement much, much sooner."
Definitely not. That would mean only 32,5 Wh per mile (20 Wh per km) if using 100% of the capacity. Physics is harsh but it is physics, so don't even hope to fool it.

Posted by: François | Sep 4, 2007 1:24:36 PM

8 miles range on the plug, that pitiful! Need at least 40 miles which is what the volt is intended to have. To get that range you need a bigger battery and powerful electric motors, if your motor(s) can push you around with good acceleration there is no need for an engine drive transmission: a little engine generator plus larger electric motor(s) is less expensive compared to a big engine with transmission and generator plus larger electric motor(s). Sure your long range driving might be less efficient in serial mode then a parallel setup, but now you’ll have enough space and money left over for bigger batteries and greater plug in range.

Posted by: Ben | Sep 4, 2007 1:46:14 PM

As in most innovations, U.S. always have great ideas but poor implementation, where as Japan never put out a good idea but were able to copy, execute, and implement hardware well. I would not be surprised if series hybrid cars will be a great success and Japan will be able to adapt and manufacture excellent series hybrid cars. Case in point is HDTV, idea came out of the United States, at the time, Japan had a lousy analog HDTV std, but they are able to produce the best digital HDTV now.

Posted by: Rob | Sep 4, 2007 2:14:10 PM

Toyota has already slapped together and are testing a PHEV Prius with a range of 8 miles. I'm not sure what the extra cost would be, but doubling the pack size, modifying the ECU/s, and slapping an inverter in there can't be that expensive. GM otoh has nothing more than a mockup with a few lead acid batteries, an electric motor, and a laundry detergent bucket...
http://sirymarketing.blogspot.com/2007/03/more-on-volt.html

Provided affordable and suitable batteries do become available in a few years, I don't see why Toyota wouldn't have access to them as well and upgrade their range accordingly. Unless there's some back room government of corporate advantage GM has that Toyota doesn't?

Posted by: yesplease | Sep 4, 2007 2:23:03 PM

I'm not sure there's much value in flat out declarations that either parallel or series is superior to the other when the result of the analysis is so highly dependent on the duty cycle used for comparison. My own preference would be for the large battery, small engine configuration because I wouldn't be doing a lot of long highway trips.

Posted by: Neil | Sep 4, 2007 2:25:17 PM

Considering that the total typical mid-size drive train weight would be almost the same for both technologies, i.e.:

1) Parallel = 50 Kg bat + 450 Kg mech = 500 Kg

2) Series = 300 Kg bat + 175 Kg mech = 525 Kg.

the long distance highway mpg should be about the same. However, the short distance (40 miles) mpg should be much better with the series setup (no gas required) unless the parallel unit uses the same 300 Kg battery pack. Adding another 250Kg would make the latter much heavier and make highway mpg even worse.

A series 40+ miles PHEV with the smallest, very light E-flex onboard genset seems to be best way to go.

Posted by: Harvey D | Sep 4, 2007 2:41:12 PM

Will the Volt have the power people want for hill climbing when the battery range is used up? Say a long highway trip across a mountain range.

Posted by: Aussie | Sep 4, 2007 2:46:32 PM

Aussie: I guess that would depend on the ratio of up to down and how efficient the regen would be on the down. I would hope that the Volt would have a "long range" mode that would tell the genset to start running right from the start of the trip.

Posted by: Neil | Sep 4, 2007 3:06:55 PM

"Will the Volt have the power people want for hill climbing when the battery range is used up? Say a long highway trip across a mountain range."

The genset only needs to kick in when the battery pack is at 50% - that's to optimize the charging cycles and prolong the battery life (100% depth of discharge is bad for lithium ion cells). Even when the genset kicks in, there is still 8kWh of battery power left. So yes, of course it would have sufficient power. If you actually look at the batteries in terms of power delivery, and not capacity, a 16kWh A123 M1 pack would essentially have the power of 2 Killacycles - and that would be well over 600 hp! Not that the Volt's front wheel drive system will be designed to handle that of course, but it's still interesting to think about.

"What is true is that Toyota's compound hybrid transmission is a more efficient drivetrain than GM's purely serial hybrid with battery buffer can ever hope to be. The genset will be running efficiently but that won't fully compensate for the high drivetrain losses. Ergo, once you get beyond the range covered by grid electricity, the Volt will actually be a wee bit of a gas hog."

First off, 50 mpg during continuous charging isn't exactly hoggish - in fact it's a damn sight better than the 40ish mpg that the current Prius actually gets in real life. Secondly, if you consider a realistic range - say the 60 mile round trip commute that I used to commute before moving closer to work - the series hybrid's electric NET fuel efficiency would be over 150mpg.

As for "drivetrain losses" - I'm not sure where you're getting that idea, considering the sparse gear reduction needed, plus the fact that AC motors can commonly achieve over 90% efficiency. Are you referring to the dynamo/electric generator itself, and not the ICE? Or to the minimal energy lost in running the electricity through the battery?

GM's move towards serial hybrid design also frees them to explore novel genset engine designs that would be otherwise impractical for automotive use - for example, the EV1 series hybrid that had a microturbine. Toyota, meanwhile, seems stuck with the Atkinson cycle engine.

Posted by: AES | Sep 4, 2007 3:39:54 PM

"once current parameters such as driving range, required battery size and charge time are factored in"

I think this really says it all - Toyota isn't going to outright lie and say that their idea is better technologically. Instead they just seem to be stating the obvious - which is that they can get a basic Volt competitor out to market in a cheap, simple way without going back to the drawing board.

Bottom line: this was from a stockholder meeting, not a science fair.

Posted by: AES | Sep 4, 2007 3:46:33 PM

Rafael, & Ziv,

One on the firm concepts that I have held for sometime is that the arrival of the PHEV will change the dynamics of much of the World, its politics, emissions, and prospects dramatically. The only issue preventing th entire world's population from achieving a Western lifestyle is the issue of Energy for transportation.

Rafael,

Like a true engineer, I too trust and believe in the incremental improvement approach. Many here seem to feel that there are breakthrough vehicles that will make or break, a given business. I do not think so, in this case. There is no monopolistic ability to prevent very similar offerings by others. Certainly the first to the party will achieve fame and profits, but the technology is not unique to either manufacturer, or any other.

Maybe Toyota or GM will have the first PHEV in 2010, but by 2012 every major manufacturer will have their own versions to offer, as well.

The World benefits when all the auto builders do so; then we can argue about the relative merits. I will simply offer this paraphrased quotation from Dr Andy Frank. "...The best PHEV is the one with the biggest battery and smallest gen set...".

Series PHEVs are simpler but in the transition period, with still expensive batteries, maybe Toyota is correct. Perhaps the Toyota approach will prove superior by measures of early cost/power trade offs.

Rafael,

I was surprised at the expressed vehemence of your opposition to Light Water GEN III+ fission reactors. Don't foreget that I too wasan early pbut pricipled critic to the second generation of Nukes being built in the late 60s and 70s. Teh weren't contructed well, the ocntrol systmes had neve rrally been tested and NO on ehad doen a tes tot destruction of a LOC condition. Now those concerns have been answered to my satisfaction.

I urge you to research the technology, once again. I do not advocate any follow on generation of fission reactors. Those would operate too close to the edge, but the passive GEN III+ are superior to what runs today, by two mesureable orders of magnitude. These GEN II+ designs are now very massively passive, no longer requiring near instantaneous operator response and control. GE advises that its passive ESBWR can shut itself down completely unattended, and operaiting unattended for as for as long as three days. They will serve the intermediate transition years between Oil and Fusion. I think that Sub-Critical Actinide burner accelerators will be chosen to transmute and reduce the quantities of long lived, highly radioactive wastes. Even without reprocessing, which we will do, and Actinide burning, the entire quantity of the US century long usage of Fission will amount to a volume that would fit on the playing area of a single football field. To say that we can't find anywhere in the world or under it, to entomb that small volume for no longer thousands but only a few hundred years, is absurd.

Posted by: Stan Peterson | Sep 4, 2007 5:40:22 PM

Also, by choosing a configuration that ultimately derives the vast majority of its energy from fossil fuels, Toyota isn't going to win any favors with the environmentalist crowd.

Posted by: AES | Sep 4, 2007 5:46:34 PM

Ziv,

I try to look forward to the predictable technology changes and how that effects politics and the world history. The Electrification of Ground Transport is definitely one such Earth changing technology. If the first PHEVs come in 2010, the flood will build over the decade. The comparison of price, $3.00+ per gallon versus $.75 per gallon equivalent will drive adoption. By 2020, the demand for motor fuels, gasoline, diesel, ethanol or bio-diesel will start to fall dramatically.

People just do not realize how much petroleum is a one customer-industry-application product. Up wards of 80% of all petroleum is used for Transportation. If the 2020 PHEV is approaching 60 miles, then US petroleum demand will be met entirely domestically. Many an ethanol, and bio-diesel company will go bankrupt. Most of the Middle East can return to the Arab tribes warring amongst themselves with no one else caring very much.

The need to fight for Oil to jeep the world from plunging into Depression will be over. Some secondary high production cost production sources like the Canadian oil sand ventures and Venezuela heavy Oils will be pushed to the wall, reminiscent of the Syn Fuels Corp. of the Carter years.

Electricity to power the PHEV flood can be met initially by running the fossil peaking plants, (old dirtier coal, oil and Gas) at a higher percentage of the time, under load. But the economics of the that production profile will generate a utility base load building boom. Rafael won't like it but the economics of base load generation choices is pretty clear. The higher the load factor, the more Nukes win out. Electrical utilities will be constructing lots of GEN III+ nukes to replace the over used peaking fossil plants. As they come online, Utilities emissions will drop, some more.

From a pollution standpoint, the USA will have achieved clean air everywhere by 2010 or 2012, no later. We are clsoe now; ther are few unattainment aresa even now. The rest of the world will suddenly discover that their air comes into compliance even with their laggard standards, because the volume of emission will just plunge.

Now many of you simply are not as sanguine as I am about CO2. I do read all the Science papers and not the summaries. I am convinced previous fears while valid, have been massively and persuasively allayed.

But it doesn't matter. All the other GHGs gases are now in control. CO2 outputs will plunge and it will come into control without fancy taxes nor debilitating economic measures. It will happen by 2020 due to the mere acceptance of the PHEV.

I know by the truth will be widely accepted by 2012, so we won't care any more. If you don't think it is hooey, as I do, it won't matter. CO2 emission will plunge under the combined effect of massive new carbon free Nukes generating electricity and autos not producing but 10% of present carbon dioxide output volumes. Global Warming dies as an issue either way.

Posted by: Stan Peterson | Sep 4, 2007 5:53:11 PM

The word around Detroit is that a lithium ion battery on a prototype Volt exploded last week. GM engineers are upset and urgently working on determining the cause and resolution.
The Volt is said to be thoudands more expensive than a Prius. Even the PHEV Prius with enlarged NMH battery will still be considerably less expensive than the system in the Volt.

Posted by: rca | Sep 4, 2007 6:13:38 PM

"The word around Detroit is that a lithium ion battery on a prototype Volt exploded last week"

First off, there are no functional prototype Volts driving around - so this rumor is rather dubious.

Secondly the batteries they've selected to use are widely used in the power tool industry, and have an inherently safe chemistry:

http://www.youtube.com/watch?v=A9ayuFBDrSg

Thirdly, the hype about battery prices is largely just fud. The materials in lithium iron phosphate batteries are both cheaper and less toxic than the cobalt-based ones currently used in the laptop and cellphone industry - so bringing the cost below $700 per kWh is largely one depending on mass production and economies of scale.

Posted by: AES | Sep 4, 2007 6:57:52 PM

Hmm Sounds like an urbane myth. I'm not saying its impossible, but it would take something pretty drastic to get the A123 batteries to explode (based on the chemistry and the experience of the killacycle's batteries use/abuse). Speaking of rumors, I've heard that GM will dance around the cost of the battery by leasing that portion of the car.

Posted by: Neil | Sep 4, 2007 7:06:03 PM

Two different ways to achieve Plug-in vechicle.

Toyota's approach: Gas engine dominant Plug-in Hybrid Vehicle based from the proven HSD design with durable NiMH battery pack. Toyota can spend more time on refine the award winning design. Why did Toyota decided to test with double the pack? Think bipolar. Bipolar NiMH pack will not add much weight, volume or cost.

GM's approach: Battery dominant Plug-in Electric Vehicle based from the series hybrid design with exploding Li-ion in public's mind. Although A123 cells will be extremely safe, public will not be able to get over it like the diesel black smoke. That image will be there and it needs some major PR battle. Volt will be built from ground up and time is not in favor to do refinement. Where will cabin heat come from? etc.. 10 years is a very long time to catch up....

Many of you are saying 8 miles is not enough. Think about it for a second. If you are going further than 4 miles radius from your home, you will jump on the highway. At highway speed, gas engine (particularly Atkinson cycle) can perform at the most efficient load. Why would you recharge Volt battery for 90 mins (120v @ 20amp) to drive 20 mins (60mph @ 11.2kwh) on the highway?

In another words, Toyota's assessment for the most efficient use of electric or gas is more realistic. In the city driving, use electric because gas engine is not efficient. On the other hand, gas engine's efficiency shines on the highway. That idea is one of the most fundamental concept behind HSD. The more electric Prius can use, the less gas it will consume. Hence, the MPG will skyrocket. You can see all three Prius generations in this pattern. As electric motors and battery output become more powerful, MPG and performance gets higher and higher (1997->2000->2004 MY).

If PHV needs cabin heat, it can turn on the gas engine instead of using battery power.

Posted by: usbseawolf2000 | Sep 4, 2007 7:06:55 PM

The Volt is more PR than practical solution.
Its 16-kwh battery pack can supply enough battery packs for 10 HEV battery packs of 1.6 kwh capacity, or 12 of Prius' 1.3 kwh packs.

The main bottleneck in mass production of HEV's (and of future PHEV's) is availability of battery packs,
whereas the ICE and gears and clutches for a parallel-serial hybrid arrangement like the Prius can be produced by tens of millions yearly without limitation.
THE uncertainty in the future of HEV and PHEV is how cheap and how fast can batteries be produced, and whether there'll be sufficient raw material without price escalation similar to that of Nickel, upon mass production of NiMh HEV batteries.

Ergo, GM should put their priority in producing the most efficient and the most cost-effective HEV's that uses the least amount of battery that can sell in the largest numbers, instead of the other way around, gambling on the uncertainty of how cheaply A123 Nanotech lithium can be mass-produced.
Redesign and get rid of the BAS system with something approaching a "full-hybrid", like the Audi or the Peugeot system...The dual-mode system looks promising, albeit expensive...and any plan to put it inside a practical family car like the Malibu?

Then, once you have the most efficient HEV, you can run it with any alternative, non-petroleum fuels and achieve energy security, and overall energy efficiency on par with BEV. Offer a plugged-in NG version that can be charged...uh...filled up... at home...following what Germany, Pakistan, Iran, Argentina, etc. have done...Brazilians would be content to run their HEV's on sugarcane ethanol and achieve renewable-energy transportation, on par with PHEV's or BEV's getting their electricity from strictly solar or wind.

Posted by: Roger Pham | Sep 4, 2007 7:52:25 PM

If you commute say like me 66 miles a day, lets look at the mileage between the prius plug-in hybrid, the volt and a theoretical EV with 100+ miles range.
Prius PHEV:~50mpg gas + 8 miles at 125mpg equivalents = ~60mph
Volt PHEV:~50mpg gas + 40 miles at 125mpg equivalents = ~88mpg
BEV:~125mpg

Posted by: Ben | Sep 4, 2007 7:53:43 PM

If batteries were 10 times better than they are, then series hybrids (such as the proposed Volt) would be the no-brainer choice. But storing energy at densities approaching those of chemical bonds without doing it chemically is really hard. Toyota is being realistic about the state of battery art and not overly optimistic about how quickly the art will advance.

Posted by: richard schumacher | Sep 4, 2007 9:11:25 PM

Rafael,
“The regular Prius is shipping today whereas the Volt is vaporware.”

You are way off the mark calling the Volt “vaporware”.

At this point, they have a very dedicated team, including many engineers and others, working on the Volt project, as well as Bob Lutz, Vice Chairman, talking about the Volt every other week. Last week, Bloomberg News reported that GM is planning to build 60,000 Volts the first year, which will allow them to keep their costs where the were targeting.

They also have published pretty detailed specs of the car. The battery that they are using is a 16 kWh Lithium nanophosphate cathode battery. They have selected a battery supplier, (A123 Systems), who says they have the battery chemistry that can perform to GM’s specs and price range, and who is currently hiring more people for the Volt project. A123 has partnered with Continental AG, who will provide the battery management of the pack.

GM has begun advertising the Volt in two target markets, Detroit and San Francisco. Additionally, they have put out press releases several times monthly discussing the Volt progress. You may want to read some of the information they have published. For example, on June 21st, Dr. Bart Riley, VP of R&D and CTO of A123 Systems, the company GM chose to produce batteries for the Volt, discussed some specifics of the battery, and how they plan to provide the volumes GM will need.

There is much information on the Volt, and it is great for me, a PHEV enthusiast, to catch up on the latest, at least twice per month. I could go on, and on. Below is a list of GM execs that, according to GM, are involved in the Volt project, or, as you call it, the Volt Vaporware:

Rick Wagoner, President and CEO
Bob Lutz, Vice Chairman
Jon Lauckner, VP of Global Program Management
Beth Lowery, VP for Energy and Environment
Larry Burns, VP of Research and Development
Bob Boniface, Director of Advanced Design
Anne Asensio, Director of Advanced Design
Tony Posawatz, Director Vehicle Line
Nick Zielinski, Volt Chief Engineer
Denise Gray, Director of Hybrid Energy Storage Systems
Micky Bly, Director Hybrid Vehicle Integration

You should talk to Nick Zielinski, Volt Chief Engineer, who is one of many people, busting their butts every day to get the Volt into showrooms by 2010. Maybe you know more than he does about the project?

Lets face it, Rafael, there is a lot more substantive information about the Volt available than the PHEV Prius. So would you call Toyota’s PHEV project, “Vaporware”, as well?

Posted by: George K | Sep 4, 2007 9:23:53 PM

@George K:
I'm impressed with your inside knowledge and it is very informative; also, let me say that GCC is a great experience for all of us who visit often. It is especially health to read comments from people who discuss differences; but, conduct themselves as gentle people and keep the debate on subject without straying into name-calling.

Thanks to Mike for his hard work on the site! Good Information is knowledge and knowledge is power. I urge everyone reading here to share you knowledge with your every day friends so we all can help move our industries in the right direction for the good of the country.

Posted by: Lad | Sep 4, 2007 9:55:16 PM

"I have to admit that I am incredibly biased"
Say no more Ziv. That right there puts much of what you say in doubt and challenges the credibility of any comments you make about Toyota's system.

I find it funny that some of you think the PROTOTYPE plug-in Prius is a vehicle that Toyota is "pushing" against the Volt. That is wrong. What Toyota is pushing is it's own approach to hybrid vehicles. Notice that Toyota does not specifically mentions the Volt anywhere, but broadly describes a system just like what the E-Flex uses.

The plug-in Prius is a PROTOTYPE for a reason. Toyota is doing some public road tests with it to gather information that Toyota will use to develop the actual production plug-in. I will say right now that the Gen 3 Prius itself will have an electric cruising range of over 8 miles, and the plug-in production car from Toyota will have way over 8 miles cruising range in electric mode.

George K, you have mentioned nothing more than the hype and boasting that GM has done about the Volt, something which we already know about.

Let's keep in mind GM is targeting late 2010 as the time when the Volt will be on-sale. The Gen 3 Prius goes on sale way before that. Toyota's estimated timeframe for using Li-ion in the Prius is 2010-2011. If the Volt gets delayed, it will be bad news for GM and the hype will have died off.

Posted by: toyo | Sep 4, 2007 10:50:31 PM

I love this part of the process

GM do have a winner if they can deliver it

Toyota does have an installed position, and is on the defensive

This is what the free market economy is all about, I would much rather have Toyota and GM fighting over the best architecture for fuel economy, than have them fighting over the best truck towing capacity.

It will take a long time to change the direction of the automotive industry, but there are signs here of the process starting.

Posted by: kevin H | Sep 4, 2007 11:25:56 PM

you can buy now a 20kwh Zebra battery for about 10000 euros
from Mes-Dea in switzerland , battery comes in a pack with all
managment hardware onboard , and weighs 168kg .

life of battery is around 200000 to 250000 miles , it also works
in the cold , something lithium has a hard time with !

Posted by: andrichrose | Sep 4, 2007 11:39:15 PM

even if the vehicles do make it to market, a battery-powered plug-in may be no more efficient in reducing carbon dioxide emissions than the current charge-sustaining gas-electric hybrids on the road today.

A true statement which many PHEV advocates have trouble admitting.

Japan never put out a good idea but were able to copy, execute, and implement hardware well.

What a nonsensical notion that is. Who came out first with hybrids? It wasn't an American company. There's countless other examples.

it's a damn sight better than the 40ish mpg that the current Prius actually gets in real life

In real life, it gets 48, which is "50ish," not "40ish."

Also, by choosing a configuration that ultimately derives the vast majority of its energy from fossil fuels, Toyota isn't going to win any favors with the environmentalist crowd.

What percentage of US electricity comes from fossil fuels? The vast majority. And most of it is the highest-CO2-intensity, dirtiest fossil fuel out there -- coal.

as well as Bob Lutz, Vice Chairman, talking about the Volt every other week

Yes, Bob Lutz is very good at talking.

Posted by: jack | Sep 5, 2007 12:04:17 AM

With all the talk of PHEVs and alternative fuels, let us remember that oil is natural. It doesn't need to be invented. It's in the ground, it is being held captive in more ways than one but will be freed shortly. All we need is faith. Faith in the fuel that GOD gave us - not some scientist. When all else fails, nature and faith are all you have. Oil companies have rights too. Oil companies create jobs, donate money to charity and keep the economy moving. Who will pay the unemployment insurance when the entire US Military is laid off when PHEVs take off? Vote NO to "alternatives" Vote YES to whats already here - faith and nature.

Posted by: LatteLiberal | Sep 5, 2007 1:31:23 AM

@ LatteLiberal:

You're kidding, right?!

wrt Prius vs Volt.
What if Toyota just desided that Lithium batteries aren't ready for MY 2008, but need to get a revamped Prius out on the market to keep momentum and fend of competition. That does not stop them from pursuing a Lithium parallel or series hybrid for the next generation, e.g. MY 2012 - around the same time at the Volt will/may have hit the market.

Furthermore, as someone rightly said, it doesn't matter much (for sales) who puts out the first series hybrid. What matters is who delivers the best package. I don't care much about who made the first diesel - I care about who makes the best one today. (the PSA 1.6 HDi is a solid candidate - at an affordable price)

Meanwhile, for every Prius that gets sold, the environment and energy security is improved a little bit.

As a European with a 55 mile all-highway commute each way, my best option is my carpool with a 3.5 passenger average (including driver) driving diesel cars with 45-55 mpg on the highway.

Posted by: Thomas | Sep 5, 2007 2:41:20 AM

Hiya,

Why this focus on Volt & Prius, when there's http://www.zapworld.com/electric-vehicles/electric-cars/zap-x ?

I'm follwing the drive train manufacturer (http://www.pmlflightlink.com/archive/news_mini.html)
and know there'll be a leading EU-OEM in the Frankfurt autoshow, making this technology main stream.

This is crucial: let the OEM's keep their USP's and deliver _drive trains_ to them, or anyone else able/willing to retrofit existing -fleets of- vehicles.

And thereby reducing dependency, conflict, wasting resources, pollution, political/governance mediocricity

Next steps: fill'r up with http://en.wikipedia.org/wiki/Concentrated_Solar_Power and connect to the grid where you can for http://en.wikipedia.org/wiki/V2g

Ask http://www.google.org/recharge/ to adopt all this and see how many hearts the West can win in Iraq or any other region the West has problematic relations with..

Emil Möller, Maastricht, Netherlands

ps: thank you Prius, Volt, Phoenix, Think, Miles, Honda for your softening up of the market, but this is the next iteration of the EV as harbinger of an all electric society

Posted by: Emil Möller | Sep 5, 2007 3:12:40 AM

@AES

You make it sound like a serial hybrid powertrain has a compound efficiency of 90%. But you forget a few things. First you need a generator AND a motor. A real-world efficiency of 90% for each of them seems a good guess, bringing the net efficiency to 81%. I don't have figures of LiIon battery efficiency, I believe a maximum 95% (real world) would be quite a good educated guess. Furthermore you do not mention the electronics necessary to regulate all this. Let's say 95% is an equally good guess. Multiplying it all brings met to a total efficiency a little over 70%.

What few people seem to know is that the Prius drivetrain is mechanically very simple. It does not have a gearbox or clutch. In fact, the only extra it has compared to a series hybrid is a simple planetary gearset. If this can improve drive train efficiency from say, 75% to 90%, then it is a no-brainer.

I am open to correction on this, as I like the discussion about serial vs parallel hybrid.

Posted by: Anne | Sep 5, 2007 4:19:42 AM

An interesting debate on comparing VOLT and PriusPHEV. As a HEV lover and a Engineer from India where we don't expect to own any of them here in the near future, let me offer my comments.
At least in theory a series hybrid combination of engine and electric motor will be less efficient than a similar Parallel hybrid configuration in power trans mission. But when we take in to consideration the system in totality as a practical Car using these technologies there are many other factors that come into play making the whole issue very very complicated.If we take the efficiency of an engine and elctric motor coupling, it will be less that the efficiency of a the engine alone, but since VOLT will depend more on electrically stored energy overall that could make up the difficieny to the extend depending on how much stored energy is used for the drive. Admittedly a series drive is simpler and cost less in every aspect, but here also the deciding factor will be the storage battery characteristics, it cost, durability and safety as it will have be a bigger one than the one used in Parallel PHEV.
So I hope we should only wait for two of the biggest car manufactures in the world to fight it out in the market, and one of them may be coming a awinner ultimately.Let us not forget at stake is the reputaion of these giants. We have many previous example of reputed companies competing each other over differet technologies and finally one coming out as the winner.

Posted by: Vinayababu | Sep 5, 2007 4:35:00 AM

...short comment on the religious palaver. There is still an argument going on who worships the stronger god or has got his message correctly. It would not matter but the problem is, that the opposing clans are sitting on areas with hardly any or lots of oil. If I got it correctly, this god-idea may be behind the creation of oil. Halewhat?

No to serious matters:
To compare both approaches, Toyota´s and GM´s, we have to focus on the weel to wheel analyse. Until now, overall efficiency of energy power plants are not very impressive. But the technology is there to have an almost 50% efficience in fossil fuel power plants. If we would use the waste thermo energy, it would further help.

But there is another problem. Look into the toy market. Model plans and cars are more and more loaded with very high electrical energy systems.

Since this is easy to do, we will see the same at cars and trucks. So, in the near future, 500kw EV could be a common thing. I have my doubts, wheather we decrease the all around fuel consumption of our vehicles with the future EV until we implement some strict laws about it.

There is another point I want to make. Some chaps said that enineering should develop step by step. I think, it is good to have a paradigmen shift from time to time. Imagine, Brits and Germans would not have introduced turbine technology in air transport and we would still fly around with piston engine propeled aircraft...
Sometimes it needs two steps beyond the familiar.

Btw, here is another approch how to get rid of the gearbox (an secure oil supplies):
http://navy-matters.beedall.com/daring1-1.htm

Posted by: michel | Sep 5, 2007 5:58:59 AM

No to serious matters:
To compare both approaches, Toyota´s and GM´s, we have to focus on the well to wheel analyse. Until now, overall efficiency of energy power plants are not very impressive. But the technology is there to have an almost 50% efficience in fossil fuel power plants. If we would use the waste thermo energy, it would further help.

But there is another problem. Look into the toy market. Model plans and cars are more and more loaded with very high electrical energy systems.

Btw, here is another approch how to get rid of the gearbox (an secure oil supplies):
http://navy-matters.beedall.com/daring1-1.htm

Posted by: michel | Sep 5, 2007 5:59:26 AM

An interesting discussion. First, will the Volt get better mileage than the third generation Prius due out in early 2008? Not significantly. The Prius will probably average about 52 MPG overall, up 15% from the current 45 MPH. The Volt may average close to 55 MPH.

Now as for All Electric Range, the mileage figure being tossed around here is 4 miles per KWH, which is very high. In actual tests, fleet averages got about 2 to 2.5 miles per KWH. So I expect the real number will be close to 3 miles per KWH, no more than 3.5 miles per KWH average performance.

If we use 3 MPK, and we use the 8 KWH available in the Volt for AER, according to some reports, then the AER is 24 miles, not 40 miles. And if we assume that 2 KWH is available in the plug-in Prius being tested, we get an AER of 6 miles.

Posted by: Van | Sep 5, 2007 6:21:39 AM

Of course, we at CalCars.org have been following this great thread...last night we pointed to it in an email to 5,000+ CalCars-News members; here's our overall take on the discussion:

Not only do we now have an explicit carmaker PHEV "race to be first" -- we're also seeing an emerging competition over technical solutions. This development is unexpected and very positive!

Of the 30+ blog comments online, you'll get a great range of views (a few are off-topic or technically incorrect, but many are very useful). You'll see:
* the suggestion that Toyota is responding defensively to all the attention the Volt is receiving by telling its shareholders/investors that it has the better system architecture...but even less of a timetable than GM;
* sophisticated presentations of the pros and cons of both solutions;
* acknowledgment that the technical superiority of each depends on driving patterns;
* the self-evident but most important point that the comparisons are theoretical until they're in cars that people can try and buy!

-- Felix Kramer, Founder, The California Cars Initiative

Posted by: Felix Kramer | Sep 5, 2007 6:59:23 AM

Van, where do you get fleet averages of 2-2.5 mi/kWh? The values I have seen are more in the range of ~3 mi/kWh for SUVs and ~4 mi/kWh for small cars. Tesla actually gives a value of 4.9 mi/kWh for the Roadster, although I think that might get lowered since I hear they are not getting the range they expected out of the battery.

UC Davis converted a suburban to a PHEV - that gets 70 miles AER on a 30 kWh pack, that's about 2.5 mi/kWh (keep in mind the 70 mile range might not involve taking the battery from 100% charge to 0%. If instead that range is for a 100% to 20% state of charge, the electrical efficiency would be computed as 70 mi / (0.8 x 30 kWh) = 2.9 mi/kWh).

Also, we need to be careful about what kind of "kWh" we are talking about. The kWh that we actually pay for (i.e., that comes from the wall outlet) or the kWh that actually goes to the motor. The difference between the 2 is of course the losses in the system from grid to motor.

Parallel vs. Series.
This is an interesting debate. I hope some other folks out there can help shed light on this topic. From just an efficiency perspective, a series makes little sense to me. An IC engine produces shaft power. Thus, it is more efficient to use that shaft power to drive the wheels than it is to convert shaft power to electricity, store electricity as chemical energy (battery), then convert the chemical energy back to electricity, and finally convert the electricity to shaft power, which is the energy form it was to begin with! Each time you convert energy from one form to another, you have losses. So if you use an IC engine in a PHEV, use the shaft power directly, i.e., make it a parallel design.

Having said that, it seems a series could be simpler/cheaper b/c there is no need to blend 2 different power sources like there is in a parallel system. But I'm only guessing.

BTW, one interesting thought someone shared with me on this topic is that the reason some of the auto makers are pursuing a series design is b/c they are trying to make the architecture "fuel cell ready." In a series design, you just swap out the IC engine for the fuel cell. In a parallel design this won't work obviously b/c the fuel cell doesn't produce shaft power.

Anyone out there have additional thoughts on the series vs. parallel debate?

Posted by: David | Sep 5, 2007 7:38:46 AM

I agree 100% with usbseawolf2000.
In fact there is no competition. Both Toyota and GM are correct and have a good approach. The difference is that Toyota design is for the short term future (now) while GM's design is for long term when oil becomes scarce.

TODAY gasoline and diesel are still far superior to batteries in terms of energy density, so makes sense to utilize it for steady high speed highway travel. That is exactly what Prius does. Using power from batteries at higher speeds simply drains them very quickly, even 10 kWh ones. The limited all electric range of Prius also makes sense because if your trip is longer than 8 miles then it involves highway travel and high speed, which is when ICE takes over. Again, makes perfect sense. And so on. Prius is the BEST design for today.

BTW, Prius numbers seem bit low. See:
http://www.greenhybrid.com/compare/mileage/toyota-priushsd.html

Seems most Prius owners get between 48 and 51 mpg. Therefore from the next gen I would expect 60+ mpg, which is still very nice performance.

Volt which puts emphasis on all electric drive is the BEST design for the future when gas/diesel become very scarce and too expensive. Even renewable alternative fuels (ethanol and such) are difficult to produce in huge quantities that are used today. Their production scale will never match the present oil industry. Again, plenty on this topic has been said already.

Therefore, we will NOT have a choice but to use mostly electric mode for transportation. For it to be feasible and handle longer commutes to work (up to 100 miles) clearly battery technology still needs to improve - future. Providing the sufficient electric energy to recharge the huge number of cars and their batteries cannot be done using the present system of central power stations. Again, covered already (not enough coal, nukes are bad, etc.) So we'll have to start producing local electricity from home based solar and wind power sources. The future house designs will have to incorporate solar panels and wind turbines as a STANDARD equipment that will charge car batteries and server other household needs. Again future.

Thus for Volt and other electric designs to work there are still additional improvements (batt tek) and changes (house construction) that will need to be made before they can become ubiquitous.

While Toyote and GM are competitors, they are not competing with these designs. GM is trying to advance past Toyota with a longer term vision. Prius clearly is not a long term design. Toyota doesn't have a long term electric design as far as I know.

The outcome in 4-5 years when next gen Prius comes out and the first Volt comes out will be based simply on oil price. If gasoline price doubles then Volt will be ahead. Otherwise it is a coin toss.

Posted by: q | Sep 5, 2007 7:42:47 AM

David,

He planetary gears in the prius are less efficient then a conventional gear box and also provide constant parasitic loss even in full electric mode. A parallel drive would be more efficient if it had conventional gear box and two clutches (one to disengage the engine and another normally clutch for the gear box) the prius drive train is simpler and thus cheaper then that so Toyota choose it despite its inefficiencies. A serial system can us a smaller engine optimized for only one speed thus very fuel efficient as a generator, the generator when off produced no parasitic loss (beside dead weight that is), most of all a serial system is open to non-mechanical generators such a fuel cells, thermoelectics, etc.

Posted by: Ben | Sep 5, 2007 7:58:51 AM

David,

On series vs parallel, you are correct. However, series still makes sense when ICE is expected NOT to work very often because battery has the sufficient energy for the entire trip. ICE or fuel cell is just a backup power plant for extended range. It is expected to be idle most of the time. Thereforem, the efficiency losses you describe are not significant.

Think of primary electricity supply for houses, which is usually based on very efficient huge plants, nukes and coal based. Now we also have backup generators that are tiny in comparison and obviously much less efficient. Still they make sense because it is not practical to place a backup nuke next to each house when primary fails or transmission lines are broken. You compromise on efficiency and even on utility (my backup generator is 15 kW, so supplies only limited circuits) in order to ensure reliable supply. Same goes for the car. You rely 90% of the time on the battery and rarely fire up ICE.

Of course, the initial models may have to use ICE more often. However as battery capacity improves ICE will become less important and perhaps even removed at some point. So think of it as a short term aid.

Posted by: q | Sep 5, 2007 8:02:29 AM

I don't believe battery density is the problem, it’s mainly battery price. The Volt with Li-ion A123 battery can achieve 40 miles; Toyota wants to stay with its NiH because they want an in-house Li-ion battery design that unfortunately has not been working out well, so they are stuck with upgrading the existing NiH battery and 8 miles range.

Posted by: Ben | Sep 5, 2007 8:10:30 AM

I don't believe battery density is the problem

That's odd, because you earlier were obsessed with the energy density of compressed hydrogen, until you were informed it's much better (both in terms of weight, obviously, and volume) compared to lithium-ion batteries. Now energy density isn't an issue.

Makes sense.

Posted by: jack | Sep 5, 2007 8:27:18 AM

Ben,

Your belief is not important. The facts are that the amount of energy that can be stored into the volume/weight of batteries that can fit in a car affords 5-20 times lesser range.

Posted by: q | Sep 5, 2007 9:02:58 AM

Anne: Where do you get your estimate of 5% loss due to management electronics? I haven't seen a loss anywhere near that high.

AFAIK battery cost is currently the biggest hurdle to commercialization of EVs. (Higher energy and power density is always nice but the batteries currently being produced are minimally acceptable)

Posted by: Neil | Sep 5, 2007 9:45:32 AM

@Anne,

"the Prius drivetrain is mechanically very simple. It does not have a gearbox or clutch. In fact, the only extra it has compared to a series hybrid is a simple planetary gearset. If this can improve drive train efficiency from say, 75% to 90%, then it is a no-brainer."

The Prius has a computer-controlled CVT and power split device, and of course a differential. The core of which is, yes, a planetary gearset. However, the series hybrid is basically just direct drive through one, non-planetary gearset, plus the differential. So the series hybrid drivetrain is still both mechanically AND electronically much simpler! Given the AC motor's good power band, and the fewer gears for the power to go through, there will be less power wasted on friction and heat in the drivetrain.

Regardless, the rational for Rafael's original comment about "high drivetrain losses" is still a mystery.

Regulating the operation of the genset shouldn't be that complicated - just an on/off switch depending on the remaining battery pack capacity. Besides, I also refuse to believe that an ICE running at constant load and speed will be less efficient than the same ICE running under variable loads, speeds, and subject to abrupt start/stops.

Posted by: AES | Sep 5, 2007 9:56:22 AM

Wow. There's more hot air here than in a balloon! :-)

Fact: GM killed the EV-1 project due to shareholders wanting the quick profits from SUV sales. See the movie.

Fact: Battery technology is only an issue because nobody has significantly funded or incented research. Now that the market is suddenly providing capital for batteries, they are, amazingly, becoming better almost overnight.

Fact: Regardless of Fact #2, battery technology exists today to propel an auto over 100 miles on battery power alone using NiMH, or even Lead Acid (although that's certainly a challenge). The Tesla Roadster is using 10+ year old battery technology (+ their special BMS) and can get 200+ miles per charge.

Fact: Toyota could have produced PHEVs by now, and WOULD have, if Chevron had not sued them (and Panasonic) in international court to stop them manufacturing large format NiMH batteries. This wouldn't have stopped them, except that until Toyota OWNS a battery type, they won't produce a significant PHEV.

Fact: The Volt may be staffed, but given GMs track record on innovation, I will never buy one, assuming they ever even see the light of day. There could be a Volt here NOW if GM had not killed their EV-1 project.

Fact: GM has approached other Lithium cell companies with offers to buy them out. When they refused to sell but offered good deals on OEM orders, GM said 'No thanks'. Now GM is 'partenering' with Chevron/A123 to get LiFePO4 batteries. Amazing that.

The whole ugly ball of shame is shown up by the guys in their garages doing BEV race cars and 80+ mile range machines from converted pickup trucks, geos, datsuns and other street cars. If I can design a 100+ mile range vehicle using Lead Acid batteries, GM should be able to design one that can do better, and have a lot faster results as well.

Posted by: Mr Resistor | Sep 5, 2007 9:58:25 AM

The Toyota Plug-in technology is superior specifically because of its limited battery-only range. Think about it. The greater problem is too many cars and too much need for long-distance travel.

The Toyota battery pack is smaller, (reducing cost), and may need to be scaled to reach a more practical range of perhaps 20 miles, but not much more.

The shorter the driving range, the better. Of course, the plug-in hybrid's fueled ICE can extend driving range and reassure motorists they won't get stranded, but higher fuel cost fairly discourages long-distance driving and encourages mass transit use.

Again, the real problem is too many cars and too much need for long-distance driving. The Toyota Prius and Ford Escape technology is in this and many other important regards superior to GM's Volt.

Posted by: Wells | Sep 5, 2007 10:03:17 AM

Toyota could have produced PHEVs by now, and WOULD have, if Chevron had not sued them (and Panasonic) in international court to stop them manufacturing large format NiMH batteries. This wouldn't have stopped them, except that until Toyota OWNS a battery type, they won't produce a significant PHEV.

Really? What's the patent number?

Posted by: jack | Sep 5, 2007 10:39:58 AM

AES,

Your observations about the efficiency of an ICE optimized for a single rpm amd load is textbook correct. A variable out put is the bane of efficency, as the ICE must operate sometimes at inefficient operating points for most of its lifetime.

The inefficiency of gears sets, is much higher than Anne thinks; a planetary gearset was the original transmission that Henry Ford employed in his Model T. Under any definition it is a gear train, and a very simple one. Multiple gear ranges provide higher parasitic losses but the optimization they provide in the operating range of the ICE, more than offsets the frictional losses in the multiple gear train.

Posted by: Stan Peterson | Sep 5, 2007 11:57:26 AM

Wells,

Putting a smaller gas tank on a car would not cause people to live closer to where they work and in the same fashion a smaller all electric range is unlikely to cause people to move closer to work.

Posted by: Patrick | Sep 5, 2007 12:40:45 PM

Really then how are there EV with range above 100miles? Density is not a problem unless there not enough space in the car, price is the problem.

Posted by: Ben | Sep 5, 2007 12:52:38 PM

"Density is not a problem"

cf.

"compressed hydrogen has extremly poor energy density" [yet not as poor as LiOn batteries -ed.]

Make up your mind.

Posted by: jack | Sep 5, 2007 1:01:57 PM

Not surprised a small island nation - with the most to lose from potentially rising ocean levels due to warming and ice melt - is leading the way to automotive sanity.

Tentative steps in the right direction I hope.

Bravo.

Posted by: chillpill | Sep 5, 2007 1:18:58 PM

Very well then, let go with aluminum-air or lithium-air batteries as they have superior densities without the use of tanks of highly combustible compressed gas, both can be feed with pellet/paste fuel which can achieve near theoretical energy densities, with lithium that would be a energy density approaching gasoline (not considering the efficiency different of a 25% efficiency ICE verse a 55-65% efficient lithium-air cell)

Posted by: Ben | Sep 5, 2007 1:22:41 PM

Jack,

"Really? What's the patent number?"

Check out US Patent #5558950. Guess who owns it? Yup, Ovonic.

http://www.freepatentsonline.com/5558950.html

Posted by: usbseawolf2000 | Sep 5, 2007 1:24:34 PM

Let me help you out here:

http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=13&f=G&l=50&co1=AND&d=PTXT&s1=5558950&OS=5558950&RS=5558950

This is the actual filing with the USPTO

Posted by: Patrick | Sep 5, 2007 1:50:33 PM

Check out US Patent #5558950. Guess who owns it? Yup, Ovonic.

Looks like a crap patent. How can they limit the size of an application to above 10 Ah? USPTO grants some pretty dumb patents.

It'll expire in 2013 anyway.

Posted by: jack | Sep 5, 2007 2:16:58 PM

Real-world data on a serial-hybrid can be found at the ACpropulsion.com website:

http://www.acpropulsion.com/reports/Low_Emiss_Range_Ext.pdf

Note on page 10 table 4, that even for a vehicle as small as a 2-seat T-zero (BEV) trailering a genset from behind, the hwy efficiency is only 38 mpg! This is far worse than the Prius with Hwy mpg of ~48 mpg, even though the Prius is heavier and can seat 5. Note that the T-zero is a very efficient BEV with consumption of only 170 wh/mi, whereas the Prius is known to consume 250 wh/mi in electrical mode. See:

http://www.acpropulsion.com/tzero/efficiency.htm

This should lend more credence to those stating that parallel-serial hybrid like the Prius is more energy-efficient than pure serial hybrid (myself included).

Also noting on the same web page that while the Tzero consumes 1919 BTU's of natural gas equivalent/mi, the Honda Insight Hybrid ,at 56 mpg,consumes only 2,050 BTU's of gasoline LHV. Likewise, the Prius at 55 mpg (confirmed in my own Prius) is capable of comparable efficiency as the Tzero even though the Prius is much bigger.

Posted by: Roger Pham | Sep 5, 2007 2:20:56 PM

> Posted by: AES | Sep 5, 2007 9:56:22 AM
>
> Wow. There's more hot air here than in a balloon! :-)
>
> Fact: GM killed the EV-1 project due to shareholders wanting the quick profits from SUV sales. See the movie.

CORRECTED FACT. The EV1 was stillborn, not "killed". It offered two types of batteries: Delco-Remy Lead-Acid and Ovonics NiMH. GM owned 100% of Delco and 60% of a joint venture in Ovonics Batteries at that time. GM had acquired 102 lead-acid battery patents up to that point since 1937 and has since been granted another 19. Despite being the biggest richest car company on the planet on the date the EV1 hit the streets, Surretten Batteries sold a deep discharge L-A battery technology that stored 13% more power at 5% less weight, with a 10-year warranty and 15-year design life.
http://www.h2-pv.us/wiki_100mpg/tiki-index.php?page=GM+Lead-Acid+Battery+Patents

GM divested Delco & it's share of Ovonics was sold to Texaco (who became ChevronTexaco, then became Cobasys) just after crushing the EV1s. Cobysys refuses to license NiMH batteries in large enough packs for BEVs, so HEVs or alternate technology are your other choices. GM partnered to kill off the nation's electric streetcars, remember?
http://en.wikipedia.org/wiki/General_Motors_streetcar_conspiracy

GM has to EARN trust in BEVs, and is given no more "benefit of the doubts".

> Fact: Battery technology is only an issue because nobody has significantly funded or incented research. Now that the market is suddenly providing capital for batteries, they are, amazingly, becoming better almost overnight.

CORRECTED FACT. ABC, Chrysler Corp., Ford Motor Co. and General Motors Corp., U.S. Advanced Battery Consortium.
http://www.uscar.org/guest/view_team.php?teams_id=12

By 1998, release date of EV1 Generation1, the ABC had spent $189,000,000 on battery research.
Effectiveness of the United States Advanced Battery Consortium as a Government-Industry Partnership (1998)
http://books.nap.edu/openbook.php?record_id=6196&page=15

> Fact: Regardless of Fact #2, battery technology exists today to propel an auto over 100 miles on battery power alone using NiMH, or even Lead Acid (although that's certainly a challenge). The Tesla Roadster is using 10+ year old battery technology (+ their special BMS) and can get 200+ miles per charge.

CORRECTED FACT. The EV1 got 55 to 95 miles range on 18.7 kWh L-A batteries, and 75 to 130 miles range on the 26.4 kWh NiMH battery pack in 1998. The contemporaneous Toyota RAV4-EV got similar range using 1999 technology.
http://www.evchargernews.com/CD-A/gm_ev1_web_site/specs/specs_specs_top.htm

...

> Fact: The Volt may be staffed, but given GMs track record on innovation, I will never buy one, assuming they ever even see the light of day. There could be a Volt here NOW if GM had not killed their EV-1 project.

CORRECTED FACT. The Ansari X-Prize will change the rules of the car game. If GM goes out of business is no concern of mine. GM, the leopard, can never change its spots. 40% of all Hitler's Wehrmacht drove GM-Opel cars and trucks, and 35% more drove Fords. Corporations at best are amoral and at worst are immoral and psychopathic.
http://h2-pv.us/Bush-Hitler/Slave_Machines/Slave_Machines.html

IF Chevron-Cobasys is involved in anti-trust suppression of socially important technology they need to be prosecuted and broken up, by some future justice department who doesn't fire federal attorneys for enforcing laws against campaign donors that is.

> Fact: GM has approached other Lithium cell companies with offers to buy them out. When they refused to sell but offered good deals on OEM orders, GM said 'No thanks'. Now GM is 'partenering' with Chevron/A123 to get LiFePO4 batteries. Amazing that.
>
> The whole ugly ball of shame is shown up by the guys in their garages doing BEV race cars and 80+ mile range machines from converted pickup trucks, geos, datsuns and other street cars. If I can design a 100+ mile range vehicle using Lead Acid batteries, GM should be able to design one that can do better, and have a lot faster results as well.

If you want to get fired from GM engineering, design a better BEV. Here's a list of Lead-Acid battery patents to teach you how to do it: 0261435 0276099 0282414 0285529 0286809 0292433 0439416 0491684 0510604 0523689 0620593 0620855 0699492 0712995 0720326 0903752 0956919 1164464 1375317 2217787 2241627 2696515 2883443 3375137 4046642 4425192 5266423 5641591 6316148 6447954 6479179 6566010 6569571 6586136 6707660 6949313. Everything earlier than 4425192 is public domain royalty-free. Need more ideas? Go to http://www.h2-pv.us/wiki_100mpg/ and check out the patents on carbon-foam electrodes, aerogel-fullerines, reticulated vitreous carbon electrodes. The website is 3 weeks into development and has 398 wiki pages under editing so far, mostly copies of US patents, on how to make the 100 mpg car to win the Ansari X-Prize $10,000,000. Come back in a couple of months and there will be over 1,000 patents to glean.

The really interesting challenge would be to make 100 mpg car using only expired 20-year-old GM patents that they never used when they had the monopoly. THAT would be fun.

Posted by: Lion Kuntz | Sep 5, 2007 3:33:47 PM

Roger-

Your comparison between the prius and the tzero series hybrid is not valid for a couple of reasons.

1) You are comparing two very different engines. You are comparing a 1.5L, 4-cylinder 58hp engine, to a motorcycle engine that produces 20 kW (26.8hp) of electric power. For the mere fact that you are comparing different engines, the comparison is scientifically invalid. The major takeaway from the tZero series hybrid study - which you missed entirely - was that an engine running at constant speed and load converted more chemical energy into useable (either mechanical or electrical) energy than the SAME engine running at variable speed and load. I bet the Prius engine would be a great candidate for series hybrid engine if it were unshackled from the transmission.

2) The tZero was lightweight, but the addition of the genset trailer introduced more weight, more aerodynamic drag, and more rolling resistance. It was a side project and an afterthought to the main program.

This isn't necessarily a more scientific comparison, but a directly contrasting example to "Prius vs tZero" is the parallel hybrids and series hybrids that GM developed using the EV1 program: http://en.wikipedia.org/wiki/GM_EV1#EV1_series_hybrid.

Even at a continuous state of charging, the series hybrid got up to 100mpg, versus 80mpg in the parallel hybrid.

Posted by: AES | Sep 5, 2007 3:40:42 PM

Why didn't they use a non-prismatic NiMH battery and an alternate method of cooling?

It seems the primary issues with the Ovonics patent are: greater than 10AH capacity, prismatic design, and the significant number of thermal considerations and cooling methods (which are all somewhat specifically stated in the actual patent). With a concerted engineering effort put into "designing around patents" the courts (in the US) typically rule that there is no infringement.

Posted by: Patrick | Sep 5, 2007 3:59:40 PM

Patrick et al. Too many cars, driving too far, for too many purposes. THAT IS THE PROBLEM!

With a limited, battery-only driving range, a plug-in hybrid creates an economic incentive to drive less, to patronize and build local economies, which over time create more destinations that are accessable without having to drive. Walking and bicycling become viable and safe travel options. Such development patterns are more suitable to mass transit systems and also encourage regional (as opposed to global) production and distribution businesses. What's so frickin hard to see about this? It's only hard to see for those whose own ideal solutions are blindingly grandiose. The simple and perhaps ONLY solution is to drive less. Duh.

Posted by: Wells | Sep 5, 2007 4:47:39 PM

Here in France, there is a serial hybrid on sale for years : the Renault Kangoo ElectroRoad. It's more a pure BEV with and added emergency genset than a real serial hybrid. In serial mode, it will take you back home at 70 km/h and a 8l/100km poor mileage, but it's better than being stopped on the roadside with a depleted battery pack. The sales number is very low because this model isnt listed on Renault catalog. The salesman think it's a joke if you ask for this car ! But i think it can get a mileage similar to the E-Volt with an efficient genset(lean burn, Atkinson..).

Posted by: Philippe | Sep 5, 2007 4:54:12 PM

Preaching to the choir wells, I live less than 2 miles from my office and walk most days unless I need to do some shopping which tends to happen one time a month for main groceries (meats & veggies from a "warehouse" type store).

Posted by: Patrick | Sep 5, 2007 5:00:44 PM

> Posted by: Roger Pham | Sep 5, 2007 2:20:56 PM
>
> Real-world data on a serial-hybrid can be found at the ACpropulsion.com website:
>
> http://www.acpropulsion.com/reports/Low_Emiss_Range_Ext.pdf

This is not typical. It may be loosely "real-world" but it does not portray the state of the arts well. This is a six-wheel vehicle with 50% more tire drag than a 4-wheel vehicle. Neither the car was designed for trailers, nor was the trailer designed for this car (it was commissioned to be towed by a RAV4-EV). It's a kludge, a hack job. Not representative of a designed series hybrid.

> Note on page 10 table 4, that even for a vehicle as small as a 2-seat T-zero (BEV) trailering a genset from behind, the hwy efficiency is only 38 mpg! This is far worse than the Prius with Hwy mpg of ~48 mpg, even though the Prius is heavier and can seat 5. Note that the T-zero is a very efficient BEV with consumption of only 170 wh/mi, whereas the Prius is known to consume 250 wh/mi in electrical mode. See:

This is a deceptive statement which misrepresents the plain english language on the page you quote from. 38 mpg is after a dead battery. A fully charged battery starting a 250 km trip (155 miles) gives a total gasoline miles per gallon of 80 mpg, next line down from your misquote, and 280 miles per gallon on average trips with periodical recharging overnight, where the extender is only operating 15% of the time.

> http://www.acpropulsion.com/tzero/efficiency.htm
>
> This should lend more credence to those stating that parallel-serial hybrid like the Prius is more energy-efficient than pure serial hybrid (myself included).

Falsehoods never lend credibility. The plain black & white details were 1 line of type away from the false misleading number you plucked out of context.

Despite the fact that the AC Propulsion concept is flawed and was flawed when it's forefather appeared in the EV1 in 1998, it still gives 80 mpg of gasoline use (not considering the half gallon-equivalent of the 16 kWh battery bank) on a long trip of 155 miles. Including the grid kilowatts and the gasoline, that's 2.5 gallons of energy equivalent, for 155 miles range, or actual 62 mpg real-world energy consumption. Integrate the IC engine onboard and ditch the extra wheels would get an improvement. Fixing the AC Propulsion design flaws would do better.

> Also noting on the same web page that while the Tzero consumes 1919 BTU's of natural gas equivalent/mi, the Honda Insight Hybrid ,at 56 mpg,consumes only 2,050 BTU's of gasoline LHV. Likewise, the Prius at 55 mpg (confirmed in my own Prius) is capable of comparable efficiency as the Tzero even though the Prius is much bigger.

And what's your point? That the sports car is a vanity trophy possession not designed for fuel economy? We knew that from the start. A Toyota Lexis doesn't get the fuel economy that your Toyota Prius does either. Why do you think that is? People don't get a custom-built Tzero for fuel economy, but instead to blow the hubcaps off Corvettes in a drag race. That's not an economy car, even at 280 mpg, and was never built to be one.

Posted by: Lion Kuntz | Sep 5, 2007 5:06:01 PM

You can read the blog of one of this serial hybrid (Kangoo Electroroad)user here : http://www.pile-au-methanol.com/roulez-electrique-2.htm A mistake on my previous post : the mileage with only gasoline is 6.5 l/100 km, not 8 and they are no more for sale since 2005. There is also a comparison VS a Prius II and some mountain trips in pure electric mode.

Posted by: Philippe | Sep 5, 2007 5:26:36 PM

> Posted by: Van | Sep 5, 2007 6:21:39 AM

> Now as for All Electric Range, the mileage figure being tossed around here is 4 miles per KWH, which is very high. In actual tests, fleet averages got about 2 to 2.5 miles per KWH. So I expect the real number will be close to 3 miles per KWH, no more than 3.5 miles per KWH average performance.

The GM EV1 got 2.9 miles per kWh at worst (55 miles on 18.7 kWh), 5 miles per kilowatt-hour at best (95 miles on 18.7 kWh) in 1998. It depends on hills, temperatures, traffic and the drivers right foot on the accelerator. Why shouldn't a better design get better performance? Why shouldn't driver retraining get better performance? The Prius retrains drivers by displaying the MPG constantly so drivers see where their bad habits are wasting energy uselessly for no benefit. Racing to each stop light to sit and wait until it turns green is a bad habit seen daily in most drivers. Looking ahead a block and letting off the accelerator to coast means you are still moving when the red light ahead turns green by the time you get there. Cars that teach good driving habits can add miles per kWh.

> If we use 3 MPK, and we use the 8 KWH available in the Volt for AER, according to some reports, then the AER is 24 miles, not 40 miles. And if we assume that 2 KWH is available in the plug-in Prius being tested, we get an AER of 6 miles.

So you used the worst numbers from 10 year-old technology, ignoring new technology that has come about since then, and get pessimistic figures. The EV1 was not optimized. It was a rush job to meet California requirements for zero-emissions-vehicles deadlines, and after the ZEV regulations were repealed the EV1 was crushed. It was designed to perform sub-optimally so that the regulations could be repealed because the EV was such a dud. The lead-acid battery technology sold by other companies in 1998 gave 13% more power storage with 5% less weight, but the EV1 was built around GM's Delco-Remy batteries and GM's 60% ownership-share of Ovonics Batteries NiMH. GM made sure to sell it's Ovonics shares to Texaco (ChevronTexaco -> Cobasys) just after the EV1 were crushed, so that an EV-hostile company would control the NiMH battery patents. This is the corporation that crushed the electric streetcars before it crushed the electric street cars.
http://en.wikipedia.org/wiki/General_Motors_streetcar_conspiracy

It's partner in that former deal was Standard Oil of California, since renamed Chevron -> ChevronTexaco -> Cobysys. GM had no incentive to make a good EV yet made on that got 5 miles per kilowatt-hour in 1998. Think how far you could go in a car made today by somebody that likes BEVs?

Posted by: Lion Kuntz | Sep 5, 2007 5:40:29 PM

or actual 62 mpg real-world energy consumption

No, it's 37 MPGe and 134 g CO2 per km.

cf.

Prius - 48 mpg, 115 g CO2 per km.

Posted by: jack | Sep 5, 2007 5:56:06 PM

Always cheaper to run on electricity if the $30,000 PHEV comes along (no road taxes)

I doubt most U.S. consumers care about CO2 instead of:

1. how much state/federal tax credit they'll get for
buying a PHEV

2. how cheaply they can refuel it
- can I make $1/gallon biodiesel at home, or
- convince/force the utility to give me a cheap rate
for overnight recharge)

3. can I get a HOV sticker for my PHEV? :)

Posted by: Bill | Sep 5, 2007 6:48:43 PM

Yeah that "smug" pollution from the hybrids, got to watch out for that ;)

Posted by: Ben | Sep 5, 2007 7:31:50 PM

AES, Lion Kuntz,

Sorry, I didn't mean to upset anyone, just trying to put out real-world data to put things in perspective.

The argument between serial hybrid and serial-parallel hybrid would be moot:

IF GM manages to put a simple (~$200) clutch between the engine and the drive train in the Volt,

so that whenever the engine runs within its high-efficiency range that exceeds the efficiency of the generator-motor's route, then the engine will transfer its torque directly to the drivetrain without any mechanical nor electrical ohmic losses.

This is similar to the torque-converter lockup clutch in an automatic transmission unit.
I've brought up this many times here in GCC but no one seems to have any opinion on it.

I wish GM the best of success, and glad that the "heart beat of America" has quicken its pulses.

Thanks, AES, for the link to the different versions of the EV1, in CNG mode, serial hybrid, and parallel hybrid modes.

Posted by: Roger Pham | Sep 5, 2007 10:53:31 PM

Roger,

I feel your pain, I have always believed a duel clutch hybrid would have been superior to a planetary gear or series hybrid.

Posted by: Ben | Sep 5, 2007 11:56:19 PM

"that whenever the engine runs within its high-efficiency range that exceeds the efficiency of the generator-motor's route"

I think you'd be hard-pressed to prove that this ever happens!

And yes, the EV1 series hybrid was a really fascinating engineering exercise. I don't see microturbines being used in the near future because of the cost of manufacturing, but it really does show how the series hybrid opens up lots of new possibilities that a parallel hybrid would never be able to explore.

Posted by: AES | Sep 6, 2007 2:28:49 AM

Series Parallel hybrid again

David,
That was exactly what I was trying to say in my first post.But these are basic theories in Engineering. Sure, those smart people at Toyota and GM must be seeing some thing extra when following separate routes.They must be preparing ground work for their future ideas. Toyota' PHEV is now ready with a NIMH battery for the market though with a limited range for pure electric drive, but when they get access to a dependable Li-ion version they need only to replace the battery to get a tested PHEV . Likewise just as other posts mention,GM may have other power plants in mind like Fuel cell, Hydrogen, new age Diesel or even BEV for the future ,that could easily replace the present ICE.

Toyota Prius is really a series/parallel hybrid design that uses the fine characteristics of both series and Parallel drives. Honda uses parallel drive, may be only VOLT look at the pure series design. For details see two links below for a not too technical explanations.

http://www.hybridcenter.org/hybrid-center-how-hybrid-cars-work-under-the-hood-2.html
http://auto.howstuffworks.com/hybrid-car.htm

The series/parallel design calls for the adoption of an ingenious planetary drive (not a Toyota patent) which could cause some loss but that may be over come by the the benefit of a series/parallel system. Prius and now Honda is also incorporating a CVT drive that slightly reduce efficiency in the Parallel and series/parallel systems.
Another positive aspect of a series/parallel system is that the ICE will be driving the Car directly at certain times improving the mileage.

Posted by: Vinayababu | Sep 6, 2007 2:54:11 AM

OK, here's my viewpoint on the series vs parallel arguement.

I accept that early series drivetrains did show quite large losses in energy conversion. However, this was largely due to inefficient generators/inverters and especially batteries. NiMH batteries (as used in the Prius) can often give out only 60-70% of the energy you first put in. That's a huge waste of energy.

However, newer lithium-ion batteries can manage 98%+ efficiency in terms of energy out vs energy in. Recent generators and motors are also around 90-95% efficient.

So I see the efficiencies stacking up as this for highway travel:

Series:
Engine - 40% (assuming gasoline on an efficient cycle)
Generator - 95%
Battery - 98%
Inverter - 90%
Motor - 95%
Overall ---- 32% efficient

Gearbox: (ie direct shaft connection to road)
Engine - 25% (much lower for reasons below)
Gearbox - 95%
Overall ---- 24% efficient

The problem with a direct shaft connection to the road is that the engine is almost always working at part-load, and hence inefficiently. More to the point, a direct-connect engine must be designed with far too many compromises on efficiency that a series engine is not subject to, so probably averages only 25% even if it could manage 30% peak.

My verdict: Series wins.

Posted by: clett | Sep 6, 2007 3:54:49 AM

@Clett,
Your Honor, the council for the defense hereby would like to file an appeal for the verdict.
The defense would like to introduce additional evidence heretofore not considered in the last verdict:

The Prius is found to have a tank-to-wheel efficiency of 37%, according to Toyota's website. No disrespect, Your Honor, but this exceeds your serial hybrid estimate by ~18%.

In fact, the Prius' 1NZ-FXE engine is capable of maximum efficiency as low as 1/5th of maximum power output, at a low a rpm as 1200 at ~70% volumetric efficiency, just enough power for highway cruise. When going downhill, the engine still maintain its output by powering the generator to charge the battery. Uphill, the battery will supply a boost to the engine, preventing the engine from too much fluctuation in power output.

Respectfully Submitted,

Posted by: Roger Pham | Sep 6, 2007 10:16:27 AM

I agree with Roger completely. Here is the paper for your review:

http://www.toyota.com/about/environment/technology/2005/engines/Well-To-Wheel.pdf

Diesel is only 23% efficient? Toyota's testing must include a lot of city stop and go driving.

Posted by: usbseawolf2000 | Sep 6, 2007 12:11:59 PM

Roger,

I think you're unfairly extrapolating the poor efficiency of the tzero's generator to series hybrids in general. The AC Propulsion generator trailer used a 250cc motorcycle engine running at very high speed. This is guaranteed to produce high friction and pumping losses; I once calculated the fuel consumption as being on the order of 0.6-0.7 lbm/hp-hr. A better-matched engine running at its most efficient setting could be close to twice as efficient.

Posted by: Engineer-Poet | Sep 6, 2007 10:07:12 PM

"The Prius is found to have a tank-to-wheel efficiency of 37%"

That tank-to-wheel figure they quote is misleading as it is the same as the PEAK thermal efficiency of the engine only in bench tests.

I've looked at the Prius efficiency/load map and if we assume that the engine peaks at 37%, but averages 32%, then the figures would be:

Prius:
Engine - 32%
PSD - 90%
Overall ---- 29% efficient

I've assumed 90% for the PSD because it is often not as efficient as a gearbox at many driving speeds. In the Prius much power is routinely put through MG1 and MG2 to convert the shaft power to electrical power by a generator which then adds torque from the motor to overcome the overall very long gearing of the Prius.

Posted by: clett | Sep 7, 2007 3:27:34 AM

Both designs have issues.

The GM Volt will have anemic power, and they seem to be betting a lot on the A123 batteries.

The Prius was designed to be a hybrid, not a plug-in hybrid. The planetary gearing allows for power assist from the engine, but will need to be redesigned to allow for all-electric operation over 40 MPH.

For a plug-in hybrid tank-to-wheels or well-to-wheels efficiency of the fuel used is a secondary consideration. You just want a tank of fuel to provide needed range. A few percent difference in engine efficiency won't make much difference to the user.

I guess I give a slight edge to the Prius, but PHEVs users will eventually demand all-electric operation at 60 MPH, and the Prius can't do that.

It remains to be seen what range of all-electric operation is optimal. You really don't want that ANY higher than needed, due to cost. I think 8 miles is a little low, and 40 miles is probably too high. 20-25 would probably be best, in my guesstimate.

Posted by: Jim Beyer | Sep 7, 2007 12:06:59 PM

@Eng-Poet,

the engine used in the Tzero was a Kawasaki 500cc two-cylinder engine. This is a quite an advanced and high-performing engine, so internal friction is minimized, especially with only two cylinders. Since the engine is used at near wide-open throttle, pumping loss is not an issue. The engine was not run at very high speed, since there is no need for it to do so.

@Clett,

The 1NZ-FXE engine must be capable of near 40% peak, since minus drivetrain loss, the Prius is capable of 37% efficiency already. The purpose of a full hybrid drive train is to run the engine only at its most efficient regime, while at lower loads, the electric motor will provide sole power. The Prius' drive train is very simple, hence very little mechanical loss. Even the motor generator route in the Prius, which only conducts but 1/4th of the engine torque at cruise, is very efficient, due to the fact that at part load, an electric generator and motor are at their highest efficiency (95-97%).

At higher loads, as in serial-hybrid drive train wherein the generator and the motor assumes 100% of torque load from the engine, the efficiency of the generator and the motor will drop from a rated 95% down to perhaps 85% for the generator and ~90% for the motor, since the motor is larger than the generator.

Hi Jim, were you an advocate of the methane economy before in evworld? Welcome back!
The Prius can operate in all electric mode at above 60mph. Mine sometimes does that when going down a long hill at above 60mph, and the engine shuts off while the car runs on electric power. On level road, the engine kicks in at 40 mph to relieve the load on the battery, due to the small size of the battery.
CNG car using renewable methane can provide energy security without the expense of large battery pack.

Posted by: Roger Pham | Sep 7, 2007 5:53:21 PM

"quite an advanced and high-performing engine"

It was a motorcycle engine designed for high specific power - not necessarily high efficiency. While we're on the subject of apples to oranges comparisons, the series hybrid mini that PML flightlink put out claimed to get 80mpg in hybrid mode: http://pmlflightlink.com/archive/news_mini.html

Also,

"At higher loads, as in serial-hybrid drive train wherein the generator and the motor assumes 100% of torque load from the engine, "

First off, what higher loads? The load the genset encounters is low and constant. Secondly, how is the electric motor (that drives the car) bearing any torque load from the engine? They aren't even mechanically connected. In "hybrid" (charging) mode, the generator's efficiency ALWAYS remains at its maximum efficiency regardless of what the rest of the car is doing. I could be stuck in traffic or going 100mph, the generator would still be operating at the same optimum efficiency. Perhaps you're under the misconception that the series' genset purpose is to provide real time current for the motor to use. It's not. Unlike the tZero, the Volt doesn't go into hybrid mode when it's battery has been bled dry. It still has 8kilowatt hours left.

Posted by: AES | Sep 8, 2007 2:27:30 AM

This is a great discussion about the relative merits of series and parallel PHEVs. Here are some points that haven't been brought up yet:

1) GM is not only working on the Volt series PHEV, but also on the VUE PHEV, which uses GM's two-mode split-power parallel hybrid system. The VUE's system is very similar to Toyota's Prius PHEV. So the series vs. parallel competition is not purely a GM vs. Toyota contest, since GM is betting on both concepts.

2) The two-mode parallel hybrid system likely will be more efficient than Toyota's HSD. However, compared to the Prius, the VUE is a larger, heaver vehicle, with a larger, more powerful engine. Advantage: Toyota, unless you need an SUV.

3) A series system requires Motor-Generators and power electronics large enough to transmit 100% of the available power. For a parallel system, these components only need to transmit about 50% of the available power. These components are very expensive, roughly 10x as expensive as the gearing needed for even a complicated split-power parallel hybrid gearbox.

4) On the other hand, a series system allows you to use full power for acceleration without having to start the ICE. Running the ICE for a just a few brief acceleration events doesn't sound efficient to me.

5) With a large battery, a series system might allow greater control of engine load when running, compared to split-power parallel system. This should be an enabler to run the ICE in HCCI mode. (Both systems are CVT's and can control engine speed.)

In the end, I hope both systems are produced and compete in the marketplace. Personally, I think parallel is better for HEVs, due to lower cost and greater ICE to wheel efficiency. However, once you make a PHEV with significant AER, then series will likely be better. A good point make earlier in this thread is that ICE to wheel efficiency will not be as important when most of the energy used comes from the Plug, not the ICE.

Posted by: GSP | Sep 8, 2007 8:14:29 AM

Jim Beyer, you are incorrect. Read the specs of the Prius plug-in prototype: it can travel 13km on all-electric power at up to 100km/h. That's 60mph. This is a PROTOTYPE, not even the real-deal production car and already Toyota can make it go 60 mph on electric power alone. Will the Volt be able to do 60mph on electric power alone?

Posted by: toyo | Sep 8, 2007 11:27:26 AM

RE: toyo's comment above

Of course the Volt will be able to go 60mph on electric. That's how it's ALWAYS powered.

Toyo, please at least read the article and know the slightest amount of information on the products in question before posting your comments.

Posted by: Jason | Sep 8, 2007 12:34:24 PM

Thanks, GSP for neatly summing up the gist of the debate.

@AES,

Thanks for the link to the "80-mpg" electric Mini,
but look at what's used as the generator here:
"Generator
Engine 250cc 2 cylinder 4 stroke gasoline 15kW at 7000rpm
Generator 20kW continuous at 250V 80Amp"
This engine is even worse than the 500 cc kawasaki engine for the Tzero. Running the 250cc engine full bore to obtain less than 15 kw of power (generator loss) out of a generator rated at merely 20kw, at generator efficiency no more than 80% due to running so near max rating...and you actually believe their claim of 80 mpg?

Most real-world serial hybrids are diesel-electric locomotives having nearly zero battery capacity. The generator-motor route must absorb 100% of the torque (hp) from the engine, and that's what I'm referring to. If you still have 8kwh of battery capacity left in the Volt, then why bother to run the generator? With a 50kw of engine/generator on board, the Volt can deplete its battery before needing to run the generator, since this much power will handle hill climbing 7% grade at 65mph, which is the highest hwy gradient.

Of course, if you have a big generator and big motor and use only a tiny portion of their rated power, you may be able to achieve 95% rated peak efficiency, but you'll be paying a hefty price for electrical components and hardware that may cost as much as 10x that of transmission gears used for the parallel-serial hybrid, as GSP mentioned.

Posted by: Roger Pham | Sep 8, 2007 1:19:21 PM

Toyo-

100km/h is ~62.1 mph

And yes, since the Volt is planned to have a 160 horsepower electric motor, of course the Volt will be able to do 60mph on electric power alone. Apparently it will also be capable of 120 for a limited duration.

Moreover, given that it's an EV with a range extender, your question is confusing - what other power would it be driving on? Maybe the misconception that the genset's purpose is to provide real time current for the motor is more widespread than I thought.

Posted by: AES | Sep 8, 2007 1:25:26 PM

"Most real-world serial hybrids are diesel-electric locomotives having nearly zero battery capacity."

And thus the comparing them to a Volt is irrelevant.

"If you still have 8kwh of battery capacity left in the Volt, then why bother to run the generator?"

The purpose of this charging scheme is to optimize battery life on the lithium ion pack. 100% depth of discharge is very bad for lithium ion batteries, and so to is overcharging. The sole purpose of the generator is to maintain the battery at between 50% and 80% of capacity. The normal A123 m1 power tool cells - upon which the volt pack is ultimately going to be based - are rated at 1000 cycles at 100% depth of discharge (DOD). Keeping the pack between 50%DOD and 20%DOD is just common sense - especially to those of us who baby our battery-powered electronics! A123 even claimed in a recent interview that their automotive cells are capable of lasting through 7000 cycles.

Now granted, if a plug-in prius relies directly upon it's ICE for propulsion, the smaller battery will be somewhat buffered from charging/discharging cycles. But the more you rely upon electricity and less upon the ICE, the less this is going to be the case. And since the battery pack is smaller and rated for less range than a series, you're going to get less miles for the pack life than a series' pack, even if the cells are rated for the same number of cycles. You could always rely more heavily on the ICE to buffer the pack against this - but that would defeat the purpose of having a plug-in, wouldn't it?

Having the larger pack consistently at a higher state of charge also gives it a consistently higher voltage - which means more power when you want it!

"With a 50kw of engine/generator on board, the Volt can deplete its battery before needing to run the generator, since this much power will handle hill climbing 7% grade at 65mph, which is the highest hwy gradient."

If the genset is required to provide power in real time for the electric motor, that implies one of two things: 1) either that it must either run at variable speeds and loads to provide varying amounts of power, or 2) with the genset running at a constant speed to maintain climbing power, the current limiter will cause a lot of that energy to be wasted.

Both options 1 and 2 will result in inefficiency. The Volt's design liberates the genset from both thos