I wrote the following over in the gm-volt.com forum (I'm getting one of the first Chevy Volts) and thought you guys might be interested in it in this thread, since you've been talking about 12V battery systems.
Hybrid vehicles like the Volt and Prius have two separate battery systems: the big, high voltage "traction" battery and the small, low voltage "accessory" battery. The traction battery obviously provides the power to move the car, but it also provides the power to start the gas engine.
In the Volt, the 12 Volt battery is maintain by the "accessory power module" or APM. The APM is a DC to DC converter that takes high voltage (380V?) from the Volt's traction battery and converts it to ~13.0-15.5 Volts in order to maintain the low voltage accessory loads (including the Volt's computers and modules). It also charges the 12V system's battery, also know as an "absorbant glass mat" (AGM) battery. It does this (charges the 12V battery) when the car is running or charging, but not when parked and unplugged.
Both the APM and the 12V auxiliary battery are located in the rear of the vehicle under the removable rear hatch compartment floor.
Someone had asked a question about jumping the Volt. The scenario that you'd need a jump for is when you've somehow managed to drain the 12V battery (e.g. leaving lights on). In that case, you just need to connect to the 12V battery and give it a little juice, to literally boot up the brains so that the car will start up.
I am nearly certain you can't jump the car if it has a dead traction battery (the HV battery), but it's nigh impossible to run that battery dead anyway. The accessories don't drain the traction battery when th car is parked, and the car won't let you drive it until the traction battery is completely dead -- it stops at 25% SOC (we think) and certainly well before 0% SOC.
Now, there's also the opposite situation: jump starting another car FROM a Volt. Absolutely not. The 12 V battery in the Volt is designed to boot up small electronics, not turn a big gas engine.
Hybrid vehicles like the Volt and Prius have two separate battery systems: the big, high voltage "traction" battery and the small, low voltage "accessory" battery. The traction battery obviously provides the power to move the car, but it also provides the power to start the gas engine.
In the Volt, the 12 Volt battery is maintain by the "accessory power module" or APM. The APM is a DC to DC converter that takes high voltage (380V?) from the Volt's traction battery and converts it to ~13.0-15.5 Volts in order to maintain the low voltage accessory loads (including the Volt's computers and modules). It also charges the 12V system's battery, also know as an "absorbant glass mat" (AGM) battery. It does this (charges the 12V battery) when the car is running or charging, but not when parked and unplugged.
Both the APM and the 12V auxiliary battery are located in the rear of the vehicle under the removable rear hatch compartment floor.
Someone had asked a question about jumping the Volt. The scenario that you'd need a jump for is when you've somehow managed to drain the 12V battery (e.g. leaving lights on). In that case, you just need to connect to the 12V battery and give it a little juice, to literally boot up the brains so that the car will start up.
I am nearly certain you can't jump the car if it has a dead traction battery (the HV battery), but it's nigh impossible to run that battery dead anyway. The accessories don't drain the traction battery when th car is parked, and the car won't let you drive it until the traction battery is completely dead -- it stops at 25% SOC (we think) and certainly well before 0% SOC.
Now, there's also the opposite situation: jump starting another car FROM a Volt. Absolutely not. The 12 V battery in the Volt is designed to boot up small electronics, not turn a big gas engine.
