Check out www.rcbatteryclinic.com for some good advice on the care of all types of batteries. Two of the quickest way to destroy or lower the lifetime of a Pb based battery is deep discharge (below 11.7 volts under load) and too fast a charge or overcharge. Always recharge as soon as the open circuit voltage falls below 12 volts and never charge a gell cell at a rate greater than 0.1C (700 milliampers for the typical 7 AMP hour gell cell used in our hobby).