One of the kids that runs around our marina had a really nice older wakeboard boat he absolutely loved. Because of his driving record he did not have insurance on it.

Cheap Chinese battery charger burned it to the waterline one night .

If you guys ran those boats occasionally instead of rafting up and playing stereo wars all day you wouldn't need to change those batteries.

My opinion; I use name brand chargers, no HF stuff except on a stand alone battery. Keep all the bats in the boat, lawn mower, etc connected to 3-stage chargers every year. Putting a charger on a timer, I've never tried it should work. Only issue I could think of is the connected charger while not turned on could put a slight drain on the battery, how much depends on the charger.

Batteries short out on there own too. Have had many(10-12?) melted/'blown up' at the shop that the alternators where fine and batteries where not on chargers.

MY IMHO is that if the batteries are left in the boat, charge them up full, and undo the + cable to each battery, before the boat get's stored.

If batteries are inside, charge them here and there, every month or two or three is fine, and unhook when done.

I've seen enough melt, 'blow up' that I do not leave them on a charger when I'm not around. ie: at night, or if gone for the day, or etc....and speaking of which, when charging I make sure to walk by one in a while and touch the top and side of the battery to make sure they are not real hot.

A melted / 'blown up' battery suks bad ! Had to evacuate the shop for a few hrs once. Bad stuff !

my gibson stays in the water sometimes for a couple seasons at a time, charger is on 24/7 with the xantex never had a issue, just pulled it this year and removed batteries, saw they were from 07, unreal...pepboys brand !! before I changed to the smart charger killed batteries regularly. Had a friend install a new xantx charger a few years ago after seeing how well mine worked, only lasted a couple of years..guess chinese made now ?? anyway tried a couple of harbor freight chargers(which I have used several with only one failure) and had a battery meltdown just as you described a month ago, no idea what happened, amazing boat did not burn...

I dont think its always the charger, some cases i think its the battery. A $125 Schumacher burned my shop down.

Some times stuff just happens

I just remembered a number of years ago a golf cart battery exploded when I stepped on the pedel to start it. This was a gasoline engine power one where you push the pedel and it starts. Scared the crap out of me thinking some one just shot a gun next to me. Hot summer usage guessing it gasssewd out and the engine spark set it off.