Hi, new member and new to the Fiat 500. I have a 59 plate Fiat 500 Pop which is great apart from my one issue. Often when I start the car and put on the rear window heater the engine cuts out, this also happens occasionally when sitting with the engine running at lights or junctions. My initial thoughts are it's battery related as the battery in looks tiny in comparison to the space it sits in. Just looking for a little advice on what the issue could be? Thanks in advance ?