What saghoqst said is exactly correct, and thanks for clarifying the ICE connects to the wheels as low as 35 mph, instead of 70 that many people say.
I also want to emphasize to the original poster that the traction battery is ALWAYS online when driving, even when the ICE is running. With the nature of how the volt operates, the ICE is never generating the exact amount of energy that the vehicle demands. Thus there is always some energy going into or leaving the battery, even in extended range mode. This is the beauty of how the Volt operates, or any PHEV vehicle. It doesn't make since that all cars and trucks don't work this way. In time, they will....or be fully BEV.
-Eric
I also want to emphasize to the original poster that the traction battery is ALWAYS online when driving, even when the ICE is running. With the nature of how the volt operates, the ICE is never generating the exact amount of energy that the vehicle demands. Thus there is always some energy going into or leaving the battery, even in extended range mode. This is the beauty of how the Volt operates, or any PHEV vehicle. It doesn't make since that all cars and trucks don't work this way. In time, they will....or be fully BEV.
-Eric