The REDARC Smart Start SBI212D is a microprocessor-controlled dual battery isolator used in a dual battery system. It is designed to be used as a solenoid priority system to protect the start battery from excessive discharge while allowing the auxiliary battery to supply non-essential loads. And its compact size makes it easy to install. The SBI212D provides 12 volt DC incorporating 200A of continuous ratings and is designed for extremely heavy-duty operations. This dual sensing model isolates the start and auxiliary battery in a system where the auxiliary battery may be charged by solar panels, an external AC battery charger, or another external source. The SBI212D also allows the start battery to be charged by the external source once the auxiliary battery reaches 13.2V. It features fault detection and LED indication of operation to warn the user of instances of voltage drop, over-voltage, or excessive current draw conditions. Its components prevent the solenoid from generating high voltage transients, making it better than a diode battery isolator. The SBI range facilitates additional charge via your vehicle's alternator. Equipped with full surge protection, the power saving technology of the SBI212D is used primarily in 4WD and commercial vehicles and provides a safe way to charge an auxiliary battery.