Ammeter

An ammeter measures electrical current in amperes (A). Some older motorcycles had an ammeter gauge on the dash showing whether the battery was charging or discharging; modern bikes usually show a voltmeter or just a warning light instead.

In the workshop, the current range of a multimeter, or a clamp meter, is used to check how much the alternator delivers and to find a parasitic drain: something that slowly empties the battery while the bike is parked, such as an alarm, a tracker or a faulty regulator.

To measure drain, connect the meter in series between the battery terminal and the disconnected lead, with the ignition off. Never connect an ammeter directly across the battery, as it acts as a short circuit and can blow the meter's fuse.