Voltmeters & Ammeters
Voltmeter or Ammeter?
To put it simply, a voltmeter monitors the voltage in your battery. An ammeter monitors the rate of charge or discharge in the electrical system.
An ammeter will show when the electrical system is discharging (indicating a fault in the charging circuit), but a voltmeter will also give some indication of how long the vehicle can be driven with the system discharging.