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Toyota Takes A Swipe at GM’s E-Flex

Toyotaphv1
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.

Toyotaphv2
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
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)
Voltage 202 - 500V
Battery charging Power source Household electrical power
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.)

Resources:

Comments

Ziv

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.

Lad

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.

Lad


Ziv@

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

Brian

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

George K

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.

Lou Grinzo

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.

Rafael Seidl

@ 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.

Rafael Seidl

@ 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.

KJD

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

Ziv

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.

z

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

Fred

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.

dave

George,

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

Matthew

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.

cidi

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.

CTE

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.

François

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.

Ben

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.

Rob

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.

yesplease

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?

Neil

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.

Harvey D

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.

Aussie

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.

Neil

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.

AES

"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.

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