Alternator Help

[matk]

Symptoms:

Sat idling the other day in traffic when the electrical charge warning light suddenly lit up and the voltmeter dropped. Quick test on the wipers showed going slower, so I'm assuming a battery charging fault which is prob alternator related?

I'm going to dive under the engine cover to look for loose/broken wires (he says hopefully) but assuming the worst and everything looks fine am I right in thinking Alternator? Whats the best way to test one or are there any common faults I should look for.

Incidentally ever since I've had the car (3 years) on start up it can take up to 10 secs for all the guages to start registering and the voltmeter to climb off it's stop. I'm wondering have I always had a charging issue and I've just lived with it without realising?

Desperate to sort as I can't drive it to a garage and I need it fixed for Hethel!

[Tentenths]

With the engine running (fast idle) and all lights etc switched off stick a multimeter on the battery terminals. If the alternator's working you should see a charging voltage of around 13.5 - 14.5 volts.

[hilly]

Yeap stick a volt meter across the battery terminals.

The battery terminal voltage on it's own ranges from 12.8 ish (fully charged) to below 12 (when getting flat).

The optilmal battery charging voltage is 14.4V (this what the electrical system should be at when driving the car), so if you rev the engine up a bit this is what you should measure at the battery.

As you add load (headlights, heated rear screen, interior fan etc) this should drop a bit (due to resistive losses in the alternator lead), but stay around 14 volts until you reach the max output of the alternator.

If it is down at around 12V with minimal load even when reving it (to say 2000rpm) then the alternator is suspect.

Hilly

[matk]

Exchange alternator from PNM fitted, all correct again. Many thanks for your help, Hethel here I come!