For winter storage - You pull batteries out of the boat and charge them once a month with a FLOAT charger at 1 to 2 amps in stored warmer areas. It is important to make sure your fluid level in the battery is proper if not add distilled water to the proper levels before charging .

I can not tell you about all the bad stories I see and hear from owners charging their own batteries thru out the whole winter - hooked up and left in their boat. Many end up with a bad result and or even a battery that they killed themselves.

One example as we speak - I have a rec I/O fish N ski boat in that had a very well known name 3 bank battery charger that over heated very badly while the owner left it plugged in for about 2 months. The charger is completely melted and the boat was stored in his garage. I have no idea how the whole boat did not burn completely down by the way the charger looks, he is very lucky.

This is also a very well known 3 bank USA made charger, with the float system. Never had a built in charger until this boat. In the past always pulled batteries and charged with granite digital never had issue and always checked water level. Trying to figure out bad battery or charger?

Guy in the Mopar hobby lost his garage, classic car and a lifetime worth of tools and parts by leaving a battery on charge.

Unfortunately it's not an uncommon story.

Pull the batteries - check water level, fully charge and check again in a month - repeat. Plugging in and forgetting is asking for trouble in the long run.

Get a CTEK battery charger.

So... Battery's are relatively cheap, what have you done to mitigate the damage? Acid splashed inside a boat just can't be a good thing!

You can have a cell in the battery short out and the charger will see the battery as having 10V, so it will go into fast charge. Since the battery is bad, it won't come up to normal voltage and allow the charger to drop down to absorption mode and then into float mode. So charger will stay in fast charge, battery will become smoking hot, and bad things to follow. Not to mention the odor

Have had this exact issue happen to my cruiser twice with Interstate batteries each 3 yrs old. Luckily both times I caught it before the batteries exploded, but they were very hot and boiling. Replaced batteries and good to go. Charger (ProMariner 1240plus) still running strong.

you need to use a "smart" charger that indepently monitors and charges only the battery that needs it then shuts completly off , have a Xantex on my gibson

This one is suppose to be a "smart" charger.

•DeltaVolt® Intuitive Charging Technology
•Waterproof, dependable, rugged construction
•Independent outputs
•Fully automatic / multi stage charging
•Zero spark technology
•Battery maintenance mode
•On-board diagnostic codes
•Temperature compensated
•Advanced microprocessor controlled
•Battery systems available: 12V – 48V
•LED lights indicate the state of charge
•Reverse polarity protected
•No installation restrictions
•FCC Parts A & B interference compliant
•DC charge cables = 5ft. AC power cord = 3ft.
•Approved and meets ISO 8846 Marine standards
•Ignition protected (US Coast Guard 33 CFR 183.410

Oh I Forgot this:

•TROUBLE FREE – Just Plug It In and Forget It! (Quote)