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12V 140 Amp Dual Battery Smart Isolator Pro Complete Kit - VSR - Voltage Sensitive Relay

  • $ 64.50


12V 140 Amp Dual Battery Smart Isolator - VSR - Voltage Sensitive Relay - Complete Kit

  • 12V, 140A, 13.3V cut-in voltage, 12.8V cut-out voltage, Suitable for 12V 4WD, marine, truck, caravan & camping applications
  • If you need to isolate your vehicle's starting battery from its auxiliary battery, this SCA dual battery isolator kit is an easy to install option. You can use it with your 4WD, marine vehicle, truck, caravan, or for camping applications. The battery isolator is surge protected, keeping your vehicle and battery safe from unexpected surges.
  • When the engine is started, starting and auxiliary batteries are separated allowing only the starting battery to be charged. When the charge voltage reaches 13.3 volts the Voltage Sensitive Relay engages allowing both starting and auxiliary batteries to be charged. This is indicated by the red light in the top LH corner being illuminated.
  • When the engine is stopped and the battery voltage falls below 12.8 volts the VSR disengages separating the start and auxiliary batteries, at this point the indicator light will be out and the auxiliary battery continues to power any accessories without risk of draining the starting battery.
  • No alternator or ignition connection needed

Installation kit Specifically designed for RV & Boats.
Use for dual battery applications. This automatic relay distributes charging amperage between two batteries. Perfect for “house” and starter battery applications in power-sports applications.
Especially important for vehicles with winches, large stereo systems, cab heaters,light bars and accessories with large electrical demand.
Kit includes:
12v 140amp Smart Battery Isolator with mounting screws.
8.5 mm x 6000mm Red Cable with two 8x 5/16 connecters.
10mm x 600mm Black Cable with two 4x 5/16 connecters. Positive Marine type battery clamp.
Negative Marine type battery clamp.
Copper lugs 6×5/16
copper lugs 6×1/2
Red heat shrink 20mm x 35mm
Cable ties 4.5mm x 30mm
Fully automatic priority charging for main battery.
12V 140A isolator with Cut-In:13.3V, Cut-Out:12.8V
Easy 3 wire connection at the battery.
Uses exisiting wiring in vehicle
No voltage drop.
Compact size 2“ x 2.5” x 2.5“
No heat sink area required.
Water resistant.
Meets (SAEJ1171)certification.
Operation temperature range:
-30 to 105°C (-22°F to 221°F)


A smart isolator is the ultra-simple and most technologically advanced method of automatic battery isolation. These units can be installed between batteries with a common ground to automatically control the charging process to the batteries but continue to provide isolation when a charging source is unavailable.


The small size and rugged construction of these units allow for quick simple installation for even the most novice DIYer.

The smart isolator is also “Dual Sensing” which senses the charge of both batteries. If either battery is receiving a charge, e.g. a battery charger is connected to the auxiliary battery; the relay will engage and charge both batteries. The advanced technology always insures that the first battery is fully charged (13.3v) before connection is made to the second battery. This prevents problems that may result from your charging source being too low in amps to charge all batteries as once.

If placed in linear sequence between each battery the isolator units can provide proper charging for several batteries in a multiple battery setup such as in larger boats that may have 2 or more house batteries.

How it works: The smart isolator allows two batteries to be charged at the same time. When the engine is started and either battery reaches 13.3 volts, the relay engages, allowing two battery banks (start and accessory) to be charged simultaneously. When the voltage drops below 12.8 volts (eg the engine is stopped), the relay disengages, separating the batteries.

This system eliminates the possibility of draining the start battery and protects sensitive electronic equipment powered from the house battery from harmful engine start up spike.

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