I am a leisure boater and the boat is mostly unattended during the winter months. I can get access to a 240v mains supply.
The boat has 4 x 110Ahr 12v leisure batteries, sealed lead acid type. When I am absent there is nothing electrical left connected, except the auto bilge pump. How can I keep these batteries in a good state of charge as simply as possible?
I'm guessing it has to be some sort of automatic trickle charging system, but what size charger would I need, and is it safe to leave it on unattended for up to say 8 weeks?
There is also a 110Ahr starter battery, but to keep things simple I am assuming I can leave that alone, as it is only ever used for a couple of seconds each time I start the engine, and the alternator will recharge that quite quickly.
I know there are very sophisticated monitoring/charging systems around, but far too expensive for my needs, and I really want to keep it as simple (and cheap!) as possible.
Any advice and suggestions will be very much appreciated, thanks.
Brian