Indicates in 5 steps via 3 LEDs the actual charging condition during operation of an 12 V accumulators. Thus it is easier to control the accumulator and a total discharge can be prevented. In addition it is checked whether the accumulator is in order and it receives the full charging voltage from the battery charger. (If the Battery guard is connected during charging of the battery.) The Battery guard is designed to monitor a battery in a closed, active circuit. Very low consumption of less than 4.9 mA!