Not convinced my alternator is working...

PostPost by: roy4matra » Thu Sep 20, 2012 7:26 pm

Stuart+2 wrote:Steve,

Start your car then screw up the idle. Then disconnect the earth lead from your battery. Crude but effective.

If it keeps running then your alternator is doing some work so go from there.

Cheers,


I have been an auto electrician for 40 years so I'm speaking from experience here.

Please Stuart, don't advise disconnecting a battery whilst the engine is running and the alternator charging, as it can blow the alternator. When you disconnect the battery you remove the load from the alternator and the voltage can climb rapidly until it blows. It was different with dynamos. People used to put a good battery on a car to start it, then disconnect and switch battery to one which was flat to charge it. The dynamo charge kept the engine running whilst the batteries were being switched. When alternators came in and people did the same, they wondered why they were blowing alternators! Some of the early alternators fitted separate Zener diodes which would blow (like a fuse) and protect the alternator. Replace the Zener diode and it would work again. These days they are either built in the electronics or they don't bother to fit them so you would have to at least change the regulator pack.

Hope this helps.

Roy
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PostPost by: Stuart+2 » Thu Sep 20, 2012 9:22 pm

Point taken Roy - but it's always a maybe.

I've been getting greasy for a long time and I've never seen it happen once.

Anyway, hopefully the issue is resolved now.

Cheers
Stuart - Sydney
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