The voltmeter shows accumulator tension.

If the voltmeter shows voltage from 12 to 16 V at the movement of the car, the accumulator means it is charged well. If the sensor constantly shows voltage below 11 V and higher than 16 V, the accumulator means it is discharged or in system of recharge of the accumulator there is a malfunction. Address experts for check of system.

Prevention The sensor can show tension less, than 11 V, during a short period at start of the engine. It is the normal phenomenon.