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The Volt May be First, But E-Flex is the Key

Although the first E-Flex concept—the Volt—is using a combustion engine genset, GM is also at work on a fuel-cell variant that will use the upcoming 5th generation stack. Click to enlarge.

While it was the introduction of the Chevrolet Volt—a plug-in series hybrid electric drive vehicle (earlier post)—that generated the most excitement at the North American International Auto Show, it is the accompanying announcement of the E-Flex system that is the key, according to Nick Zielinski, chief engineer for the Volt.

The Volt represents the first application of the E-Flex System, a developing vehicle architecture that will encompass a range of compact to intermediate vehicles with all-electric drive systems (the “E”) powered by electricity from a variety of sources (the “Flex”).

Broadly defined, the E-Flex architecture consists of an electric drive motor, on-board storage for electricity (battery or fuel cell), on-board mechanisms for producing electricity, grid charging (plug-in) capability, and the associated power electronics and control systems.

E-Flex vehicles can include the genset-powered plug-in series hybrid (such as the announced Volt), a fuel-cell hybrid, or a pure battery electric vehicle. GM envisions a range of genset options for the E-Flex vehicles, including engines optimized to run on E85 or E100 and biodiesel.

There is much overlap between E-Flex needs and work being done in other parts of GM—specifically fuel cell vehicle development and the mechanical hybrid systems. (In its evolving taxonomy of offerings, GM refers to its existing portfolio of hybrids as “mechanical hybrids”—i.e., the engine provides mechanical drive power in addition to the electric drive power.)

The drive motor in the Volt, for example, is the same system being used in the Equinox Fuel Cell Vehicle. The upcoming 5th generation fuel cell stack that will be applied in a GM fuel cell vehicle will also find its way onto an E-Flex platform.

And although it is not yet determined, it is possible that the battery pack work being done for the development of the Saturn VUE Green Line plug-in two-mode hybrid (earlier post) will also apply to E-Flex vehicles.

Of all the elements, the electric drive—the motor and the controller system—is the farthest along. The technology in the motor is already on the road in the Equinox fuel cell program. We’ve been working the details of those systems—the controls, the inverter—for the last three or four years. We’ve made major advances in motor efficiency, and also in the size of the controls and the inverter, which are substantially smaller than a few years ago. And we have plans in place [in the fuel cell program] for much more compact inverter packages.

The generator itself is technology very similar to the [drive] motor. We feel we can share a lot of the technology between the two—the electronics controls are very similar.

Least mature is the large energy store battery. The new work is more in the battery pack. The challenge is the systems integration of all those cells. One of the key elements of integrating the batter pack system is cooling, and understanding temperature deltas across the pack as your charge it.

—Nick Zielinski

In working through battery pack management and control, GM combines simulation-based analysis, hardware cycling tests and then into vehicles for road testing.

We depend very heavily on the computer simulation work, and also depend heavily on component-level testing.

—Nick Zielinski

Presumably, the work being done on integration and control—and the development of optimal operating strategies—for the battery packs in the VUE plug-in hybrid will support the more rapid deployment of E-Flex vehicles (and vice versa).

There are organizational intersections where work is done, that can merge together where it makes sense on the E-Flex. We need to come up with the most efficient and highest level of component sharing with E-Flex—and we are setting up the organization to make that happen.

—Nick Zielinski



Gosh I wish I could get by on the 40 miles per day most of you assume will work perfectly fine for the average commuter. It’s the number I see constantly when an electric is mentioned. Frankly I think it will never sell around the Baltimore/DC area. Take my own commute as an example; from house to work is 46.6 miles for me each day, then I have the addition of getting the kids to/from school which is an additional 34.8 miles for 81.4 miles minimum, then there’s a trip to the local mall for my two hour walk each day (I have bad knees and need a solid level surface without potential trip hazards to walk on so walking in the neighborhood won’t work, and treadmills bore me to tears), that’s around 30 miles (I haven't found the shortest route means for it yet so I maybe able to shorten that) so make it 111.4 miles if I want to get exercise, then throw in the occasional trip to the grocery stores so that some days I might be pushing 140 miles a day. Got an all up electric for me? Oh and since my daughters school and my work are in exactly opposite directions if I move closer to one I move further from the other, so moving (even could I afford it) isn't an option.
And if you think that's bad you should see the mileage I was piling on when I worked field service for a computer company servicing the Baltimore/DC Area. I pulled calls from Springfield VA to the MD/DE line.
Housing prices in the DC Area are so bad that many lower level employees are forced to move as much as two hours away (at highway speeds) from their work. The commuter rail lines are at capacity and every station is overflowing already so for the vast bulk it’s drive or starve.
Those here who slam hybrids and keep singing the all electric car’s praises might just want to consider that there are some of us that just might need something other then an oversized electric scooter. I drive a ten year old Ford Escort which is all I can afford right now so perhaps I’m out of the race either way, but a hybrid (when I can someday afford one) is still my first choice.


hampden wireless

Larry, I am Balto/Wash area and have a 27 or so mile commute. I could plug in at both sides. I do similar distences SOMETIMES with site calls and therefore I would just end up using gas. I have no problem with that. Unless the price of the Volt is crazy I would want one.

About gas going stale.... Its possible but not with a well designed fuel system unless you really make it sit for half a year. We have gas last a year in our wood splitter and it works fine. I imagine taking long trips every few months as I do now would use the gas up.


Keep a few (1-3) gallons at most in the tank, if fuel quality is a concern. That way, you'll use it up by the end of the month. Gasoline also keeps for ~60 days in a gas tank, and 1-2 years with stabilizers.


Roger Pham writes: for autobahn passing power or police evasion maneuvering.

Now we're talking! Police evasion is something that I definately look for in a car.


Larry wrote: Gosh I wish I could get by on the 40 miles per day most of you assume will work perfectly fine for the average commuter. It’s the number I see constantly when an electric is mentioned.

Larry, 40 mi in electric mode is for a PHEV. No one is proposing a BEV with 40 mi range, except maybe golf cart makers. A guy like you will just burn a little more gas in the PHEV, that's all. If gasoline ever becomes unavailable due to the next neocon geopolitical adventure, All the folks living two hours away from their job better invest in air mattresses.



The problem is not the vehicle setup, it is your choice of extreme commuting. Average commute (taking the extreme ones such as yours and the ultra short ones such as my 3 mile round trip) is under 40 miles a day so yes, it would suffice for the majority of the US as not everybody is willing to put up with 4 hours of commuting everyday.



AFAIK in addition to cooling problems the main problem reducing efficiency of smaller gas turbines is boundary layer friction; the smaller the turbine the larger surface area compared to internal volume.

IIRC turbines in the 100 kW range are only about 20 % efficient, while larger turbines with are about 40 %.


Someone commented in the last article about GM's "Vote for the Volt" survey on their website. I would encourage anyone who thinks they have a good thing going here, and Vote for the Volt. Here's our chance to let GM know they are on the right track with this idea.


I belive in batterie driven car. all car companies should agree as to the placement of the batterie and use batteries of the same size easiley accessibles.The adeas is that when you run out of batterie on the road you can drive to the service station and get an other fully charged one faster than it takes to get a full tank of gas.



Here is the site, in case anyone missed it.

It may not seem like a big deal, but it just might be.


Actauly the genset battery car is VERY old. Back in the old days my great gresat or great duno qich granddad drove a battery truck around delivering stuff. In the back he kept a small moonshine powered generator in case the batteries ent flat on him during the winter months. With that little cuker running even if the batteries had completely died he could and did more then once limp home at 5 mph. It was also the ONLY way to start up a battery car back then in the winter.


Great comments but haven't seen anyone mention; ultracaps which store enough energy for acceleration without killing the battery and can be recharged when up to speed where only 10 Hp is needed at the wheels; all diagrams show power to the wheels but seem to ignore the fact that a motor is a generator in the braking mode; a pelter pile (which is nothing more than thermocouples in series) could convert unwanted heat from the ICE, motors, batteries and vehicle interior (in summer) etc. to recharge the batteries. Also by reversing the polarity they could cool the same components.


The reson they dropped ultra caps is because the newer batteries whil no more potent capcity wie then older lith ion can now handle alot morepower. The result is assuming they are careul the battery can take it.

Part o the work right now is ensuring the batteries actauly can take it over the long haul and dont also need an ukltra cap bank to level the spikes. Because if they do thats ghona take up more room and money.

Duncan Munro

How about a lightweight array of solar cells on the vehicle's horizontal surfaces, so that the car is charging, off the grid, while the driver is at work or during the weekends? I would like to see a vehicle in the Chev Aveo size bracket, eqipped with a 500cc V-twin engines and hybrid electric-battery-solar drive. Even a 20% range extension via solar would be a real boon, while a 500cc engine with battery assist should provide enough power for hwy speeds and hills.

Rick Leeland

The solar power is definitely being considered. I read somewhere (can't find the article at this point) that one of Volt, Tesla, or Motorcars SUT is considering mounting solar panel on the car.

But the space on car is really small compared with home roof. Thus more emphasis is on placing solar panel on the driver's home roof:

"Tesla plans to offer home roof mounted solar-photovoltaic systems through Solar City that will offset power used by the home charger, allowing 50 miles (80 kilometers) of travel without burdening the power grid, and thus making the package "energy positive" for a driver whose average daily mileage is less than that."

For those who decide to do so, the genset will be mainly safty/backup.

Maurice Turgeon

What if the interstae highway system had a series of coils imbedded into the surface to power cars in a certain lane? A toll could be levied to use the lane and charge the batteries and power the vehicle. The frequency of the induced current could be regulated to limit and even control the speed of the vehicle, much like the synchonous speed of all induction motors.


Hello all:

I thought some of you would find this interesting in regards to some information regarding the Volt I found on another green Blog website that interviewed Chris Paine, the Director of "Who Killed the Electric Car". He was at the Detroit Auto Show and had the following comments about the Volt:

Sebastian - We came to Detroit for the unveiling and the Volt looks great. It's a beautiful design and the result of what looks like earnest and incredible hustle at GM over the last 12 months. I was impressed. The proof, of course, will be when the car is sitting in your or my driveway, but in the meantime you can be sure that all of our pressure as consumers and citizens has made a difference.

GM has listened and made some good decisions to return to the EV table in earnest. I do not agree with their press faulting the EV1 nor do I believe that everything must wait for the perfect lithium battery; but by the same token I don't feel that this is just a PR play at GM. We talked to senior executives and many employees who looked us in the eye and spoke from their hearts. One executive said "the public won't forgive GM twice" which is a revealing and accurate comment.

From what I can see, GM is doing the right thing and I'm supporting them as long as they keep making good decisions and moving plug-in cars into production reality. It's a week we can all be proud of.


So as you can see, even Chris Paine liked what he saw in the Volt concept.

Roger Pham

Trouble Maker,
Thanks for appreciating the wry humor in "police-evasion maneuvers." For millions who grew up watching "Duke of Hazzard", this is argueably of somewhat importance in choosing a car.

However, creating a highly-efficient yet highly-profitable vehicle with decent performance is not a joking matter but is a life-or-death matter for GM.


jb:  Capstone claims 26% efficiency at a 30 kW size, but even that's not so great.

Larry:  The Tesla roadster would be perfect for you.  Failing that, the Chevy Volt would let you eliminate a large fraction of your gas consumption.  If you plugged in at home, it looks like you could get to work just as the engine kicked on; if you could charge at work, you could get home ditto, and if you could plug in at the mall (requires public charging infrastructure) you might be able to run the whole week without an ounce of gas burned.  You'd need a light foot, though.

Maurice, if you think pavement is expensive, wait'll you see the pricetag for that idea.

wintermane, you need to knock off the sauce.


If your talking about the general horrid typing that isnt drink its .. something else and bad bad typing . If its my general.. oddness.. im eccentric not drunk... VERY eccentric...extremely amazingly eccentric.

Anyway with luck they will make a battery design to replace lith ion before too long. I know they are trying various methods even super ultra caps to do so.

If not with luck he fuel cell will comntinue to improve as fast as it is now for some time and that will make it betterthen lith ion before too long.

Fram what I can glean from things I think its possible that by 2030-2040 we may see small 50 kw fuel cells and tanks to store h2 going for less then the cost of an engine and transmission.. and that h2 might actauly hit the goal 3.5bucks a kg or gallon equive or however they messured it. Cheap enough by far.


At last count, as of Wed. morning, 12/17/07, There were well over 17,000 Votes for the Volt on the GM website. That's encouraging to see. SJC has the address posted for anyone interested (see above).


And neingo a new contender for energy storage just popped up a new ultra cap thats a fair bit better and alot cheaper then lith ion is comming soon. Now we dont know how well ultra caps hold a charge I dont think they do forlong.. but for something like the vp;t its perfect.


GM is definitely on the right track here. I am a little disappointed that they chose a turbo charged 3 cilinder engine. Instead, they should go after the HCCI engine. As some of you know, these engines are extremely difficult to control (when sudden power changes are required). However, in a series configuration, these engines can work in steady state which allow electronic controllers to slowly react to any changes in power demand. These engines have a very high thermal efficiency and they also allow different kinds of fuels to be used.

Jack W Hildenbrand

What if I was to come up with a unit that could be placed in the trunk of an electric car. That would run on it's own(magnetically) and also produce power to keep the batteries charged in an electric car.

I think I have this unit.

Thank you: Jack W Hildenbrand


Sounds like Jack drank the Steorn kool-aid.

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