Somebody wrote:
When I had a trailered boat, I was told to bring the battery home to keep
it in the basement and keep a trickle charger on it. Many people who
don't want to bring the battery home, will use a solar panel trickle
charger to keep the battery fully charged.
I'd recommend a float type battery maintainer rather than a trickle charger.
The old trickle chargers can still overcharge or boil off a battery over a
long period.
The newer, "smart" battery maintainers keep the float charge voltage below
14.4 volts.
I use them for my motorcycle batteries during winter storage. The work
great and are not expensive. Plug 'em in and forget them until spring.
http://www.boatandrvaccessories.com/VEC-080.htm
Eisboch