rrolsbe
Member
In most cases using a Jumpstarter/jumping from another vehicle ,without lifting the negative cable, would probably work and be safe; however, not knowing why the 12V died, i like to error on the side of caution. After the contactors close ,I would wait a couple of minutes before removing Jumpstarter or jumper cables. I am pretty sure you would only need to wait until you hear the pumps start after the contactors close, which is just a few seconds? What needs to be operational is the DC-to-DC converter to supply 12V power. When I disconnected the negative cable after the car transitioned out of sleep state, the car was drive-able and seemed to be fully functional. I did get an onscreen error that the 12V battery was disconnected (which was true). After returning home, I would charge and analyze what happen to the 12V battery before reconnecting it to the car.