Voltmeters

VDO 52 mm voltmeter gauges for watching battery and charging voltage on cars, trucks, boats and generator sets. A voltmeter gauge for a 12 V system reads 8 to 16 V, and one for a 24 V system reads 16 to 32 V. The range covers Cockpit International (24 V), Cockpit Vision (12 V and 24 V, with stud mounting) and SingleViu gauges in 12 V and 24 V scales.

A voltmeter needs no sender. It connects to switched ignition power and earth, so it shows the system voltage whenever the ignition is on: about 12.6 V at rest and 13.8 to 14.4 V with the engine charging on a 12 V system, double that on 24 V. A reading that stays at battery voltage with the engine running points to an alternator or wiring fault.