Current Output

Check battery for full charge. Recharge or replace, if necessary, before performing test. Disconnect negative battery cable from battery. Disconnect "BAT" lead at alternator output terminal. See Fig 1.

Fig 1: Test Meter Connections for Alternator Current Output Test Before testing, be sure battery has full charge.
Connect D.C. ammeter, set in 0-100 amp scale, in series between alternator "BAT" terminal and disconnected "BAT" lead wire. Connect ammeter positive lead to "BAT" terminal and negative lead to "BAT" lead.
Connect positive lead of voltmeter (range 0-18 volts minimum) to "BAT" terminal on alternator. Connect negative lead of voltmeter to good ground. Connect tachometer and reconnect negative battery cable.
Start engine and immediately reduce engine speed to idle. Adjust carbon pile rheostat and engine speed, in small increments, to obtain an engine speed of 1250 RPM and voltmeter reading of 15 volts.
CAUTION: DO NOT allow voltmeter reading to exceed 16 volts.
Ammeter reading should be 50 amps or more. If ammeter reading is less than 50 amps, alternator should be removed from vehicle and bench tested. If ammeter reading is at least 50 amps, alternator is operating properly.

NOTE: Battery specific gravity should be above 1.220 for properly regulated voltage check. Charge battery or use good test battery before testing regulator. DO NOT leave uncharged battery in circuit.