do not trickle charge your batteries. That will overcharge them and kill it. What you need to invest in is a new battery (obviously) and either a three-stage microprocessor-controlled temperature compensating charger...or a volt regulated float charger. Keep the battery on it during the winter and you will be good to go come nice weather. The three-stages can be had for about 60-70 bucks, and the float chargers can be had for less. Pretty much, the three-stages are better because they automatically switch between bulk, absorption, and float. Depending on the batterey, you may be able to go four-stage and also get the power of equalizing as well.