What to do with boat batteries during winter storage?

[Winnipesaukee Divers]

Here's a story I found on another boating site... Boat batteries, who would have thought?

Posted By: Jud - s/v Sputnik
Date: 1/13/06 1:19p.m.

"Have just learned that a friend's house burned down last night --fire likely started by boat batteries in the basement that were being charged, though I don't have all the details yet. The woman is a keen Cal 20 racer and apparently had some batts trickle charging in the basement of her house. Fire started late last night; smoke alarm eventually went off, but she wasn't able to put out the blaze with a fire extinguisher b/c it was too big by the time she got to it. The house has essentially burned to the ground...all of her belongings gone, but her dog was saved. She still --alas--has her beloved boat, although it's to small to live on temporarily.

The follows immediately after my own shore power outlet/cable probably near miss with onboard fire...don't screw with electricity...and be goddamn careful if you have boat batts charging at home."

Follow up post:

"I crawled through the burnt out house yesterday helping my friends salvage whatever they could (not a whole lot) and I saw where the fire started, in a closet. It turns out that the batteries were not then being charged --it was a deep cycle batt that was being stored for a few months. So, gassing hydrogen from the battery likely wasn't the cause.

A thin wire metal storage shelf, the kind you buy at Ikea and screw into the wall in a closet for extra storage space, fell off the wall directly onto the battery --who knows whether or not the screws for the light shelf had wall anchors and fell, or if the shelf was overloaded and fell. Maybe both. Anyway, it clearly fell right onto the battery terminals, creating a dead short; the battery obviously got very hot and ignited things around it. There was no wiring or gas lines around where the fire started; and the shelf was fused/melted to the top of the battery, so this was the immediate conclusion I came too.

In short, don't put boat/car batteries inside your house... "

Well, I guess this makes my case when I say, "Just leave them in the boat, you'll do more harm to them by taking them out. Besides, batteries only last just a few years in a boat anyways."