Another alternative would be to replace the obsolete and technologically
inferior flooded cell battery with an AGM type battery and never have to so
much as look at it for years. In addition to removing battery maintenance
from your life, you also enjoy faster recharges, negligible self-discharge,
and no gassing. I've been on this program for two and a half years now and
it's been one of the best things I ever did for me and my boat. An example:

http://www.lifelinebatteries.com/marinebattery.asp