Alternator: Testing and Inspection

C1 Test conditions

- battery must not be charged by a battery charger during test as this will cause incorrect results. To prevent damage to diodes, observe the following:
- alternator and regulator must be tested together with battery
- battery must not be disconnected until alternator is at complete standstill.





Note: Use rigid connections and avoid using aligator clamps as this causes voltage drop that affects test results.

C2 Test method

Method Connections With Battery Fully Charged:

- connect alternator as shown
- run alternator until it is at approx. 60 °C (140 °F).

Voltage must be kept constant at 13.5 V to ensure maximum magnetic effect from alternator. (Since regulator is mounted on top of alternator it could affect results.)

C3 Warming-up alternator





Note: Adjust loading resistor to obtain approx. 14 V (this is necessary since alternator is operated without a regulator).

Load: 35A alternator 25A
55A alternator 35A
70A alternator 45A
Speed: 58 r/s (3500 rpm)
Temperature of alternator casing: 60 °C (140 °F)
Time required: approx. 2 min.

C4 Checking alternator current





Take two measurements at:
- 33 r/s (2000 rpm)
- 67 r/s (4000 rpm)
Adjust loading resistor to obtain 14 V, record current and check in relation to power output chart (see specifications). Indicator lamp must not glow during test. Otherwise one or more diodes is/are faulty. Max permissable voltage difference between B+ and D+/61 is 0.5 V.