Last summer I used an electric cooler overnight in my FEH (plugged into the 12V battery) and it would not start.

After a few minutes of the key being on (and possiable power coming from the HV battery to charge the 12V) the FEH did start. I would not recomend relying on this. After this experiance we only left it plugged in part of the night (2 hours or so) and then relied on the insulation and our freezer packs to get us though.

Good luck.

Chris Brown