True Smart Battery Isolator (SBI)

Dual Battery KitA SBI is the ultra-simple and most technologically advanced method of automatic battery isolation system. 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 of them 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 Driver. To make things even better this unit is “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 SBI dual battery system 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 SBI 12v dual battery setup 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.

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12V 140amp SBI with Cut-In:13.3V,

  1. Easy 3 wire connection at the battery. No need to bypass existing alternator wiring
  2. SBI’s dual battery setup have no volt drop. Conventional diode isolators incur a minimum of 0.6 volt drop.
  3. Compact size – No large heat sink.
  4. Cost effective solution


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Read the testimonials CLICK HERE!!!

You can easily see by the picture of 12v smart battery isolator setup below the unit is designed to withstand moisture with the silicone covered circuit board. Although I would not plan on mounting in a position where it would be submerged it is certainly designed to take all the splashing, dripping, spilling, and other various wet conditions that would come along.

Notice also the clearly labled connection posts and the black common ground lead. To be even more convenient all four side are designed with “knock outs” so that you can easily route your connecting wires in any direction.

Smart Dual Battery isolator
12V Smart Battery isolator


The Battery Sensitive Relay allows two batteries to be charged at the same time. When the engine is started and the start battery reaches 13.3 volts, the SBI 12v smart dual battery isolator engages, allowing two battery banks (start and house) to be charged simultaneously. When the voltage drops below 12.8 volts (eg the engine is stopped), the SBI 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 spikes.


2.66″ x 2.66″ x 2.11″


  • DC Power: 12V
  • Continuous Current Rate: 140A
  • Intermittent Current Rate: 170A
  • Back-up Current at 12.5V: <=13.0mA
  • Ignition Protection: UL1107/UL1500
  • Operation Temperature Range: -30 to 105°C T


SBI Isolator Installation

Dual Battery Wiring Diagram Setup



tag: 12 volt battery isolator switch, 12v battery disconnect switch, 12v battery isolator relay, 12v isolator switch