The battery monitor circuit (05P0607) monitors battery voltage.

If battery voltage drops to 22 V, [LOW] indicator comes on and the buzzer sounds.

With “BATT CHARGER switch” set to “AUTO”, the charger starts charging the battery

when the battery voltage drops to 24.5 to 25.0 V, and stops charging when the battery is

charged by 28.0 to 28.5 V automatically. If the switch is set to “MANUAL”, the battery

is charged in continuity. The signal to control charging is “3. CHARGE-L” signal which

turns ON/OFF relay K1 on the AC power supply line of BC-6158.