Auto Isolator I, Model #: 091-139-2-12

auto isolator
  • System consists of a controller that detects when a vehicle's alternator is charging the main battery and then closes a solenoid to tie-in charge to an auxiliary battery
  • When the engine is stopped or charge voltage is no longer present, the solenoid opens to isolate the batteries
  • Uses a solenoid rather than an isolation diode which typically causes a 0.7 volt drop, thus auxiliary battery receives full charge voltage installation
  • 3 year warranty

  • Controller
    Specifications
  • Solenoid
    Specifications
  • Downloadable
    Files
  • Outline
    Drawings
  • Related
    Products
Volts to Parallel: 13.0 Vdc, Field Adjustable
Battery Load: .000125 Amps
Output Current: 3 Amps Max
Weight: .5 lbs
Warranty: 3 Years








Volts: 12 Vdc
Coil Current: .45 Amps
Contact Rating: 200 Amps Continuous, 600 Amps Surge
Weight: 2 lbs
Warranty: 3 Years








Datasheet.pdf (484 Kb)
Instruction Manual.pdf (122 Kb)











outline drawing 091-139-cont-12 outline drawing 091-139-sol-12ho
Add-A-Bat - 091-171-12
Auto Isolator 3 - 091-208-3-12












The Auto Isolator I detects when a vehicles alternator is charging the battery and then closes a solenoid operated switch to additionally charge an auxiliary battery. When the engine is stopped, the solenoid opens to isolate the batteries. Upon "cranking" the engine with a charged auxiliary battery, the solenoid is energized to parallel the batteries and provide a starting boost. If the auxiliary battery is low, the batteries are not paralleled.
Since the auxiliary battery is charged through a solenoid-operated switch rather than an isolation diode, the auxiliary battery is fully charged. The .7 volt diode drop is eliminated, as is the power dissipation in the diode. The system therefore is more efficient. The starting boost provided by the parallel batteries is especially useful in cold weather, or when the main battery is low.