Stanley 100 Amp Battery Charger/Maintainer. 100 Amp engine start helps to start most vehicles in seconds. 25 Amp rapid battery. 3 Amp maintainer keeps the battery at optimum level by charging as needed. Charging automatically stops when battery is fully charged or topped off and switches to float mode monitoring to maintain charge. Correct connect provides reverse polarity protection to assure that jumper cables are connected correctly. Voltage meter automatically checks battery and indicates battery voltage level. LCD digital display with icons lets you see operation and charging status.