Volt's 55kw on Board Generator

[kellybill52]

It is amazing to think that this car has 55kw generator that's about 55,000 watts right? I drove it on adepleted battery switch it on mountain mode, about 35miles in less than an hour I full over on the side of the road turn the car off and on then I have 22 miles available bat charge. It's just to bad that computer program will stop at 22 miles charge. Would be neat if it could charge it back to full charge on mountain mode. That's probably take maybe less than 2 hours??

I am sure maybe one day soon an internal leak a hacker or programmer inside Chevy or IBM will capitalize it, sell the code or program on how to use maximun battery kw to say 14kw instead of so conservative 10kw something.

[Ladogaboy]

I think that the measured rate for recharging in MM is ~ 18kW, so a little less than three times the 240V charging rate.

I'm not fully sure why they didn't give the option to have the car fully charge itself using the internal generator, but my guess is that it has more to due with the fact that the car was designed to limit gas burning. Also, the third charge is more than enough cushion for most mountains, and it is more efficient to run the main traction motor off the generator than to run it off of the battery that has been charged by the generator.

[solar_dave]

The point is that grid watts are much cheaper than gasoline watts.

[Cord]

BUT each wheel is also a generator so can we say we have 5 ?

[jsmay311]

55kw generator that's about 55,000 watts right?

Yeah. It's about that much.

Would be neat if it could charge it back to full charge on mountain mode.

No, it wouldn't be "neat". It would be "retarded".

In closing: BOOO!!! (Are you saying Boo or Boo-urns?). BOOO!!!

#highschoolphysics

[Kurt_Woloch]

I think there's another thing having to do with the rate at which the battery's able to take a charge. At the normal maximum 4-hour duration, the Volt charges up to 85% (I think it was that much unless it's been changes) at a nearly constant rate, which means it charges at about 0.16C, considering that up to about 65% of the maximum charge is actually available. Charging with 55 kW would mean a charging rate of over 3C. The measured rate of 18 kW would be about 1.09C (for the new 16.5 kWh battery). I doubt if the battery would be able to take a constant charge (rather than a short momentary one as provided by regen braking) at this rate up to 85% or even 88% without taking damage. Just for the record, my laptop has a 5.2 Ah battery and a maximum charging rate of 3.5A, which is about 0.67C, but that rate only goes in until the battery reaches about 62% charge level, then the charge rate drops more and more in order not to exceed a voltage of 4.2 volts per cell. I can imagine that in the Volt, charging at 1.09 C would be OK up to that 22 mile point, but above that the charging rate would have to be reduced in order not to overload the battery.

[saghost]

The car is capable of it, yes. But the car almost never runs that way - among other things, the Volt's engine isn't very efficient at high RPMs (like any other engine,) and it would disturb the driver hearing the engine screaming during normal activity. (Higher RPMs also lead to more wear and tear on parts, and higher current means more resistance losses in the wiring. High charge rates aren't good for batteries.)

More importantly, what are you trying to accomplish here? The Volt's premise is that you can use cheaper EV miles (~1/3 the cost or less, depending on circumstances) most of the time, and resort to using the engine when you have to. Using the engine to charge the battery is an inherently inefficient way - you lose more power converting to electricity, charging the battery, pulling it out of the battery, and converting it back to motion then if you'd used the gasoline directly for propulsion. (a bunch of caveats here - this only applies for a given engine, under specific operating conditions. The Volt operates its engine much more efficiently than most cars, so sometimes it makes sense for the Volt to do some of this instead of operating like a normal car.)

So you're paying more per mile than if you'd driven them on gas directly, and eliminating your opportunity to suck down cheap wall power later. I don't understand how it would help you...

[scottf200]

I've pointed this out recently but no one responded. The new Honda Accord actually has this mode. It is called "HV Charge". For the Volt it clearly goes against the stated goals of using cheaper grid watts vs gas generated watts (GM presentations say 1/5 or 1/6 I think).

This will find various references: https://www.google.com/search?&q=%22...2+honda+accord

HV Charge mode requires a two-second push on the mode button to engage. With the battery depleted, it will run the engine at all times to recharge the battery. Charge times depend more on time than mileage. Unless you're driving hard, the engine should be able to charge the battery in under an hour. But running the gas engine to charge the batteries defeats one of the purposes of a hybrid, which is to burn less fuel. (We didn't have a chance to measure fuel economy.)

[Raymondjram]

BUT each wheel is also a generator so can we say we have 5 ?

No, there is only one generator and it is attached to the two front wheels through the planetary transmission. Regeneration allows those two wheels to return the kinetic energy of the vehicle to recharge the battery while braking slightly. Those wheels are not generators!

[metalios]

Are you all saying that the Volt engine will act as a generator, but does so inefficiently? When I'm running ICE, it seems if I pick up 0 charge and 0 EV miles. I can drive for 2 hours in ICE with 0 resulting EV miles. The car also purports to regenerate charge in both EV and ICE when breaking or coasting in L mode, but again, 0 EV miles.

Is this normal, or should I be picking up a charge? It seems that the ICE generator seems only to generate enough power to drive the car.