1-2-120 Battery IsolatorThis 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 Heavy duty construction Rated for systems up to 48 volts DC, negative ground Rust-proof anodized aluminum case Stainless steel mounting hardware provided Protective covers provided for terminals Specifications: Operating Temperature: -40 to +80Adeg Duty Cycle: Continuous rating to 50Adeg C Derate linearly to 70% @ 80Adeg C Temp. Rise: 5Adeg C at full rated current (mount vertically for optimum cooling) Voltage Drop: 0.7V @ 50% load, 0.9V @ full load Alternator Sources: 1 Battery Bank: 2 Max. Amperage Input Capacity: 120 Stud Terminal Size: 6mm Dimensions (L x W x H): 6.5" x 4.5" x 3.1" Weight: 3 lbs. Note: These battery isolators are not compatible with self-exciting alternators. The alternator must have an external excitation lead. Please consult the manufacturer of your alternator if you are unsure of your configuration