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Alternator exciter cable voltage

Posted: 12 Feb 2017, 10:46
by mueslibarkid
Hi could anyone confirm the required voltage on the blue exciter cable. I have around 4.5 volts at present. The battery warning light stays on and the alternator is not charging. I assume it should be around 12v. If this is the case I am assuming a high resisistance somewhere in the charging circuit.

Thanks for your help.

Re: Alternator exciter cable voltage

Posted: 12 Feb 2017, 12:27
by dave friday
When the alternator is working correctly the blue wire should have the same voltage as the battery positive (13.5/14.5)

Re: Alternator exciter cable voltage

Posted: 12 Feb 2017, 13:16
by Oldiebut goodie
On these alternators you need at least a 2w bulb charge indicator light - too low a current and the alternator will not perform correctly. 4.5v should be enough voltage to start the alternator charging but if you have low current at the same time you can have problems, seems like you have problems with the blue wire - highly likely to be corrosion. I would remake the terminal at the alternator end of it for a start.

Re: Alternator exciter cable voltage

Posted: 12 Feb 2017, 14:33
by mueslibarkid
Thanks for your advice, I will take a look again later and remake the crimp connector.

Cheers Stephen

Re: Alternator exciter cable voltage

Posted: 12 Feb 2017, 14:40
by Oldiebut goodie
What are you using as an earth point when you are getting the 4.5v? Try with using the alternator body and then with the chassis - if there is any difference your earthing points need cleaning up/replacing.
Also the problem may well be the voltage regulator as this uses the trigger voltage to tell the output of the alternator to increase.

Re: Alternator exciter cable voltage

Posted: 20 Feb 2017, 10:22
by mueslibarkid
Hi thanks for all the advice. I recrimped the exciter cable connection and the spade terminal connection and the problem is solved.

Cheers!