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Newmar 1-2-120 Battery Isolator

Brand: Newmar Power

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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.


  • 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


  • Operating Temperature: -40 to +80°
  • Duty Cycle: Continuous rating to 50° C Derate linearly to 70% @ 80° C
  • Temp. Rise: 5° 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