Pain in the ass it may be, but your batteries will be happier spending
the winter somewhere indoors where the temp stays above freezing and
where you can clean them up and top them off once a month.

No, I will leave them outside for the following reasons:

o Tough to pull them out from the tight compartment.

o Don't want to bring more mess to my house than what I have already
brought.

o Don't want to buy another charger for charging the batteries indoor
(the current one is an "onboard" charger that is supposed to be mounted
permanently on the boat).

o According to the book on 12-volt batteries, the freezing point of
the liquid inside a fully charged battery is very low (negative 72
degree F or something), that is so low that the battery will not frozen
in where I live (Northern New Jersey). The trick is to keep the
batteries fully charged to avoid the problem. This means I need to
check the batteries periodically during the winter; this is a small
price to pay as comparing to pulling the batteries out from that tight
compartment.

Jay Chan