[CommonBear]

Probably a silly question/thought, but something that has been mulling around in the back of my mind for a while now...

Besides the major automotive manufacturer hatred of anything that will take away their parts supply business, how come I haven't seen any EVs that have a built-in gasoline/diesel generator?

I've seen lots of hybrids, but you still have issues with multiple motors and strange drive-train connections. It seems to me that it would be a lot better to have a pure electric setup, and then install a small generator to recharge the batteries on-the-fly if driving long distances. This is assuming, of course, that a small portable generator could produce enough energy to keep the car running with enough left over to start recharging the batteries at least a little.

 

[Mr. Sharkey]

My standard answer as to why series hybrids (which is what you are proposing) are not a good idea is that the efficiency stinks. Every time you convert power from one form to another, you lose some to efficiency losses. In the series hybrid, you convert chemical power (fuel) into mechanical power (engine, heat and friction losses), use that to generate electricity (generator losses), then control the power to the motor/batteries (switching/regulating losses), then convert the power back to mechanical energy (battery and motor efficiency losses) to drive the car forward.

Much better to just convert to mechanical power and apply that to the pavement in the form of traction. Less losses, better control, and off-the-shelf technology. If you must have a hybrid, running the two systems (electric and ICE) in parallel results in much better efficiency, and the two power trains can complement each other, summing their power outputs, as in the ubiquitous "Hybrids" manufactured by Honda and Toyota.

[rant time] I don't consider either the prius or the civic/insight to be true hybrids. The very definition of "hybrid" is powered by two or more sources of fuel, and these yuppie status symbols are totally powered by one fuel, evil gasoline. It's all just marketing hype. My 27-year-old VW diesel gets fuel economy equal to that of a prius without the car payments or expensive high tech assist equipment.[/rant]

IT’S NOT AN ELECTRIC CAR UNLESS YOU CAN PLUG IT IN !!!

 

[CommonBear]

Thank you, Mr. Sharky, for the information... I haven't even thought about power conversion loss and such, but then I'm also quite new to the subject as well.

And I completely agree with your dislike of the Prius / Civic / Insight. In fact, I'm still fuming over the American version of the Smart ForTwo. The European version (gasoline) gets about 60 MPG (almost 70 for the diesel versions), which is better then most so-called hybrids currently out on the market. And now that they are FINALLY bringing them over for Americans (instead of us having to buy them through ZAP), they've reworked the engine "because Americans just want more power."

End result?

40 MPG.

 

[rbgrn]

IMO a generator in an EV is really just a hybrid-electric. Think of it like diesel-electric locomotives.

 

[Cube Donahue]

check out http://www.e-volks.com/hybridconversion.html

 

[Xanerrix]

My standard answer as to why series hybrids (which is what you are proposing) are not a good idea is that the efficiency stinks. Every time you convert power from one form to another, you lose some to efficiency losses. In the series hybrid, you convert chemical power (fuel) into mechanical power (engine, heat and friction losses), use that to generate electricity (generator losses), then control the power to the motor/batteries (switching/regulating losses), then convert the power back to mechanical energy (battery and motor efficiency losses) to drive the car forward.

Much better to just convert to mechanical power and apply that to the pavement in the form of traction. Less losses, better control, and off-the-shelf technology. If you must have a hybrid, running the two systems (electric and ICE) in parallel results in much better efficiency, and the two power trains can complement each other, summing their power outputs, as in the ubiquitous "Hybrids" manufactured by Honda and Toyota.

[rant time] I don't consider either the prius or the civic/insight to be true hybrids. The very definition of "hybrid" is powered by two or more sources of fuel, and these yuppie status symbols are totally powered by one fuel, evil gasoline. It's all just marketing hype. My 27-year-old VW diesel gets fuel economy equal to that of a prius without the car payments or expensive high tech assist equipment.[/rant]

IT’S NOT AN ELECTRIC CAR UNLESS YOU CAN PLUG IT IN !!!

Having a generator in your car like CommonBear suggests is actually MORE efficient than contemporary ICEs. In my opinion
There are many advantages:
-The generator runs only when the batteries are low so you use fuel only on long trips
-you can plug it in like an EV
-costant, efficient torque
-less maintenance (generators are less prone to breakdown)
Moreover, the generator is free to run at it`s peak efficiency speed. ALL THE TIME!
One of the big problems of usual ICEs is that it has variable efficiency at different RPMs.

Chevrolet is making a car of this type called Chevy Volt, a plug-in ''Hybrid''
Many heavy machinery use this concept with Diesel generators because it is more efficient and reliable.

I hope this was helpful for you CommonBear.

Thank you
Andre

 

[mattW]

Wouldn't another problem be that it takes 6-8hrs to charge an EV and 1-2 to discharge it, so unless the generator was capable of being connected directly to the motor/controller either to supplement the batteries or to be used independant of them you would only increase range by 15-25%? I am just guessing here.