Basically, when we bought our Autotrail Arapaho 3 months ago it had 3 new batterys installed, 2x new leisure batterys and 1x Cab battery. We are having trouble with the cab battery. The leisures are fine they are showing maximum 13+ volts(solar panel on roof) but the cab battery is only lasting about 4/5 days. But on the sargent display it's reading 12v good. When you go to start it, it just labours very heavy and dies. Had an auto electrician come and look at it and he says he thinks the body control unit is faulty, it's draining the battery. I've tried searching and there seems to be a lot of issues with the fiat electrical systems. Any advice would be great, whether regards getting a new unit or even a 2nd hand part. The van is the 3.0 multijet 160. Thanks.