See www.batteryfaq.org.

I agree with the poster from Scandinavia who leaves his batteries outside. I
talked with two very experienced boaters yesterday who agree that:

1/ a good condition, fully-charged battery will not freeze in any conditions
reasonably expected in this area (and I live 2 hours from Montreal, where we
see down to almost minus 30 C).
2/ Note: "good condition, fully-charged." They don't do anything about this
except i) buy very good batteries to start with, and ii) charge them in the
Fall during lay-up, and iii) replace them after many years when they don't
hold a charge well anymore. Next season, they just start using them again,
and then repeat the cycle at lay-up. You can of course check for enough
water, check the electrolyte's sg, and I do these sporadically, but so far
the main thing that works very well for me is using a digital (not analog!)
voltmeter. Knowing what numbers to expect (i.e. the nominal "12V" is very
bad!) and correcting for temperature (see web site address above) is
critical.
3/ The internal self-discharge of a battery is minimal in very cold weather.
Chemical reactions slow down in the cold. The very place where you least
likely need a trickle-charger is where the battery is unheated. Indoor
batteries will discharge more.

Also, a completely discharged battery is not likely a problem, because you
would have known that it was malfunctioning and not have left it outdoors. A
marginal battery that had fooled you would still hold some electrolyte, and
I have never met anyone who had a battery casing fail due to freezing. Some
have bulged - but not broken. If they bulged, they were bad anyway and would
have needed soon replacement.

Also, of course, keep the battery tops clean to minimize any leakage current
between the terminals through the dust.

Remember what people do to keep back-up batteries (for flashlights, etc.) in
good condition: refigerate or even freeze them. Cold protects (good)
batteries.

====

Charles T. Low
www.boatdocking.com

====

wrote in message
oups.com...
Popular widsom has it that the batteries should be removed from the
boat before winteer storage. The boat will be stored outside, here in
Montreal,.

Question is, why can the batteries not be left in the boat if they are
fully charged before the winter and charged again in the spring?

Many thanks in advance

Matt