Yes @Ads_Essex is right about the panel. We have the panel charging our leisure battery and have a small trickle charger that is supposed to trickle charge the main battery when the leisure battery if full. We don't have a battery monitor on the main battery but i have only been out to the supermarket in the van twice in five weeks and it has started fine so i am guessing it does what its supposed to do and is a cheap addition when you are doing the electrics,here is a photo of the one we have,hope this helps