The Smart Battery Isolator is designed specifically for use in multi battery applications as a solenoid priority system to protect the start battery from being excessively discharged by auxiliary loads, whilst still allowing the auxiliary battery to supply non essential loads. Put simply, once the start battery has had some charge from the alternator, the Smart Battery Isolator will connect an auxiliary battery to the charge circuit. Similarly, if the start battery voltage drops too low, the Smart Battery Isolator will disconnect any auxiliary batteries or loads from the start battery to conserve charge.