Wikipedia has something on Lead Acid batteries here...
http://en.wikipedia.org/wiki/Lead-acid_battery
The section on CYCLES may be appropriate particularly...
"A common misconception is that starting batteries should always be kept on float charge. In reality, this practice will encourage corrosion in the electrodes and result in premature failure. Starting batteries should be kept open-circuit but charged regularly (at least once every two weeks) to prevent sulphation."
Peccavi, January 2009
