Originally Posted by peterek
My friend's fisker had 12v battery dead, so he jump started it, and was able to run few feet forward and backward. but was afraid to drive it as we dont know if HV charges 12 battery or only engine when running charges 12v.
his HV battery is fully charged so engine will not turn on untill reaches higher speed.
Does anyone the answer?
The HV charges the battery when the car is in Ready/Drive mode, regardless of whether or not the ICE engine is running. The only thing that charges the 12V battery is the high voltage system. The car does not have an engine-mounted alternator or generator.
f the car is on at least the '530' version of the software (although you want 535, since 530 was buggy) it will also charge the 12V while the car is plugged in.
If the 12V battery did die though, I strongly recommend replacing it, or hooking up an external battery tender and giving it time to recharge.