Newmar 1-2-120 Battery Isolator [1-2-120]1 2 120 Battery Isolator This heavy duty isolator allows multiple batteries to charge automatically from one or two alternators and prevents the discharge or dumping of one battery into another. Each battery is charged according to its need without overcharging and is rated for 12 , 24 , or 36 volt, negative ground DC systems. This model is a 120 amp alternator. Features: Conservatively rated diodes and a rustproof anodized aluminum heat sink case