Dual Pro Eagle Performance Series Portable 48V 15 Amp with 619 Yamaha Charger Chargers will turn on at extremely low voltage (6 volts on a 36 volt system and 8 volts on a 48 volt system) Charger promotes 25% longer battery life Safe to leave charger on continuously (24/7) with GFI outlet or surge protector Charger turns on and off automatically as needed by the batteries Proven technology engineered and built in the USA