Solar chargers eliminate dead batteries on your boat, car, RV, ATV or any occasionally used vehicle. Battery Maintainer and Solar Trickle Charger keep batteries topped up for trolling motors, fishfinders, etc. The Solar Battery Charger will replenish power consumed daily by 12V lighting systems and appliances, extending battery life. A charge controller is not needed for the two smaller panels however, in most cases, the 7 Amp Charge Controller should be used with the Solar Battery Charger to prevent overcharging.