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Charging
GavMax - 8/9/11 at 06:51 AM

What's the best way of checking that the alternator is working properly - should I check amps or volts?

Thanks
Gavin

cliftyhanger - 8/9/11 at 07:04 AM

volts. Wants to be between 13.5 and 14.5V when fast idle. Worth checking with a load on too (headlights etc) to make sure it doesn't nosedive.

Agriv8 - 8/9/11 at 07:16 AM

quote:
Originally posted by cliftyhanger
volts. Wants to be between 13.5 and 14.5V when fast idle. Worth checking with a load on too (headlights etc) to make sure it doesn't nosedive.


Id be looking at 13.5 volts at just over tickover and check again after 5 mins running.

regards

Agriv8

britishtrident - 8/9/11 at 07:17 AM

Normal way is to start by checking charging voltage .

Battery should have at least 70 % charge before testing this can be roughly judged by measuring the battery volts with everything switched off anything above 12.3 volts should indicate enough charge. At 1500 to 2,500 rpm the alternator should produce 13.4 to 14.9 volts accross the battery, repeat the test with the main heavy electrical (head lamps) loads on the battery voltage should still lie in the same range, then with the rpm at 2,500 watch the voltmeter and switch the head lamps off the voltage should not jump above 14.9v

The other main test is to check for current leaking back through the diodes when everything is switched off.