[DWade]

Why would anyone want to recharge the battery with the generator? The point of the gas motor is to extend the range, which means power the wheels. Its much more efficient to send the electricity straight from the engine/generator to the wheels then to send it into and then immediately out of the battery. In addition to being more efficient, it will also extend the battery life.

Its much cheaper to recharge the battery from the grid, and the whole point of the car is to reduce the amount of gas used. How would recharging the battery with gas help anything?

And the battery will be slightly recharged if the generator has extra capacity, but only up to a certain point, maybe 35%. Then the generator would turn off again, until the battery reached 30%, which the engineers call the customer depletion point. Then the generator would turn back on and the cycle would repeat. On the other hand, the battery may also be discharged even after the generator turns on, if extra power is needed, such as while accelerating quickly or going up a steep hill. After the power was drawn it would be replenished up to 30% again, in case extra power was needed later. This information comes from a graph that the Volt team released, that I think I saw on gm-volt.com.

As an engineering student who has closely followed the Volt's development, I can assure you that GM has done a very good job of choosing a charging strategy, as relates to efficiency, cost, and performance.