The REDARC Smart Start SBI12D is a microprocessor-controlled dual battery isolator used in a dual battery system. It's manufactured for use as a solenoid priority system to protect the start battery from excessive discharge while allowing the auxiliary battery to supply non-essential loads. The SBI12D provides 12 volt DC incorporating 100A of continuous ratings and is designed for heavy-duty operations. The dual sensing model is compact and easy to install. It isolates the start and auxiliary battery in a system where the auxiliary battery may be charged by an external source. The SBI12D also allows the start battery to be charged by the external source after the auxiliary battery reaches 13.2V. The power saving technology includes fault detection and LED indication of operation to warn users of voltage drops, over-voltage, or excessive current draw conditions. The SBI12D has components that prevent the solenoid from generating high voltage transients. It's better than a diode battery isolator based on the the voltage drop associated with a diode type isolation. The SBI12D has full surge protection and is used primarily in 4WD and commercial vehicles. Choose the SBI12D for a safe way to charge an auxiliary battery. The SBI range manages battery charge for your secondary battery banks while on the move.