BatteryMINDer Model 12117: 12 Volt 1.33 Amp (12V 1.33A) Charger/Maintainer/Desulfator Full-time battery monitoring automatically tests battery every microsecond, supplying only the current needed to maintain battery at full charge Maintain up to four 12 Volt standard, starting batteries (of similar type - in parallel). Amperage is divided evenly among connected batteries. (NOT recommended for deep cycle batteries) Does not overcharge, regardless of time connected High-frequency pulses safely remove sulphate from battery's plates that prevent the batteries from holding a full charge Adding water references Wet typed batteries. If the water level isn't sufficiently maintained, charging the battery runs the risk of overheating and cooking the battery. The charger applies current to the battery and this can cause the water to boil and evaporate.