The BM-1 (12 V) is designed to monitor performance of 12 V lead acid battery systems, including AGM and GEL types with capacities of up to 600 Amp hours. It is supplied complete with a precision 100 AMP shunt and a prefabricated cable assembly to enable simple DIY installation. The unit continuously monitors voltage, current (charge or discharge), number of amp/hours (charge or discharge), the batteries state of charge and the time to charge or discharge. It also monitors the voltage of the engine strat battery. This information leads to more efficient use of the battery, which can enhance battery life and reduce the risk of failure. Fully monitors domestic battery/bank. Monitors voltage of engine start battery.