Consumer Reports: Volt 'doesn't really make a lot of sense

[Herm]

The main issue is that the Volt doesn't get great gas mileage when using gasoline. Change out the gasoline engine for a smaller, turbo diesel and it makes much more sense-- except for the extra $3000

We have to wait until summer to see what the Volt will do in CS mode, probably better than 40mpg for the average user, and that is plenty for the occasional use.. of course you have no issues if your driving range is within the battery's limits. Diesel would be a real bad idea for the Volt, it goes bad readily when it sits in a tank for a long time.

A Prius to Volt comparison is apples-oranges, different styles for different personalities.. the Prius is too odd looking for many people. The Ford/Hyundai hybrids are a better match to the Volt for these people.

 

[walterbays]

The main issue is that the Volt doesn't get great gas mileage when using gasoline. Change out the gasoline engine for a smaller, turbo diesel and it makes much more sense-- except for the extra $3000

Do you know how efficient very small gas engines could be? I wonder how Volt might perform if it were designed the way GM had led us to believe. It looks like you'd need less than 10 horsepower to generate 3-6 kw. You could start driving the car like a pure EV, and if you made it to a charging station within range you'd never burn gas. But if the battery reserve dropped below a certain value they the generator would come on to essentially perform L2 charging. You could drive farther and faster than the electrical energy could be replenished, and then just like a pure EV you'd have to stop and recharge. But you might even be able to leave the generator running in a parking lot while you ate or shopped - basically an "anywhere" L2 EVSE.

It seems like a very small engine running at a constant speed ought to be very efficient. But the only estimates I could find of gas consumption of generators worked out to something like 15 MPG equivalent. Discussion here suggested that GM engineers considered and rejected this idea: http://naturalgasgenerators.aospb.o...enerator-at-constant-speed-more-efficient.htm

 

[smkettner]

walterbays, I agree. I would like Volt better if it had just 500cc to 750cc to charge the battery only. If you had 150+ miles to go you just push a button to have the generator come on right away. This would truely be a range extending gas engine not a gas powered car with some electric range. The engine could come on automatic but might be late in the game. Otherwise if the destination was in electric range the gas engine could be disabled. Due to carbon monoxide issues I don't think a vehicle will ever be designed to continue running after you turn it off. I suppose a CO detector could always disable the engine.

 

[AndyH]

It's clear that Mr. Gremban has his blinders on. CalCars may have pioneered the Prius pack, but other companies have taken the ball and run with it. Plug In Supply has a 10kWh pack that gives 50 miles of EV range at up to 72mph, or 100 miles of 100+MPG in blended mode.

A plug-in parallel hybrid will never displace as much gasoline as a plug-in serial hybrid. Not happening. In the case of the Prius, connecting the traction motor to the ring gear and the wheels to the planetary gear works well with a relatively small battery pack but requires an engine assist for accelerations, negating the advantages of a larger battery pack.

You didn't hit the links I posted for you, did you? That's ok.
SOME of the PHEV conversions require an engine start for speeds above 34MPH, but not ALL.

http://www.pluginsupply.com/operation/

3. Electric Vehicle Mode (EV Mode)

Electric Vehicle Mode (EV Mode) is a completely electric mode of operation. In EV Mode the gas engine will not operate. Only the electric drive is used to propel the car.

Our PHEV controller can be programmed to allow Blended Mode or EV Mode or both modes of operation.

Since Plug-In Supply has a system that provides pure EV mode at speeds up to 72MPH, that suggests that the Prius actually IS capable...

The claimed 50 mile EV range is a pipe dream, and there is no shortage of tests confirming that. Among other things, the additional weight of the battery more or less offsets the MPG increase due to increased electric range.

?? How is MPG related to 50 miles of EV range? Care to share the tests?

I could almost join you in Eeyore mode (it won't work) if I didn't know about Plug-In Supply's system...

 

[AndyH]

Here's a pure series hybrid:

[youtube]http://www.youtube.com/watch?v=Rba3_S3AobY[/youtube]

The 2000 Miata has a DC motor and 120V battery bank. The 3-cylinder Kubota D722 (1.1 liter) is directly linked to a 10kW PM generator.

...This configuration allows the generator to charge the traction battery pack as well as power the vehicle. If required, the generator can also provide full-cycle charging if the traction battery becomes depleted and cannot be recharged by the AC mains supply.

(The Zero Carbon Car, Kemp, page 255)
http://green.autoblog.com/2007/09/08/building-the-zero-carbon-car-out-of-a-miata-using-a-biodiesel/
http://www.aztext.com/zero_carbon_car.cfm

Here's another:

[youtube]http://www.youtube.com/watch?v=aWOvSTCuzus[/youtube]
http://www.endless-sphere.com/forums/viewtopic.php?f=34&t=15794
The battery tray is filled with supercapacitors. The generator will be driven by an ICE burning ammonia - no carbon exhaust.
And the kicker? It's partially funded by GM.
http://www.energy.iastate.edu/Renewable/ammonia/ammonia/2010/NH32010.html

 

[edatoakrun]

walterbays, I agree. I would like Volt better if it had just 500cc to 750cc to charge the battery only. If you had 150+ miles to go you just push a button to have the generator come on right away. This would truely be a range extending gas engine not a gas powered car with some electric range. The engine could come on automatic but might be late in the game. Otherwise if the destination was in electric range the gas engine could be disabled. Due to carbon monoxide issues I don't think a vehicle will ever be designed to continue running after you turn it off. I suppose a CO detector could always disable the engine.

And make the (maybe even smaller than 500 cc) generator easily detachable. Think of a module designed to fit in the cargo recess in the LEAF's trunk. So you would only have to carry this range extender/security engine when neccessary, and not have it taking up space and weighing you down in daily use. Don't buy one, if you don't need it frequently. Just stop by the rental shop to have it dropped in before you head out on that long trip.

The small propane or CNG fuel tank and exhaust system could be permanently mounted in the car, so that a separate combustion heater could be used at all times, preserving precious battery energy for winter driving range.

I think the primary reason car designers rule this scenario out is not engineering considerations, but perceived limitations of car buyers and drivers. The driver would have to anticipate future energy demand, and turn on the generator well in advance, to build up a sufficient battery reserve for that mountain pass or long 75 mph freeway stretch.

 

[xRB]

I am so often glad that Consumer's Reports does not get to decide which cars are sold. No one there seems to actually enjoy cars, or even to approve of enjoying cars. I imagine them to be a think-lipped grim-faced bunch.