Battery Light

[Citroenfan]

The battery light came on today and will not turn off - though actual measurement of the voltage at the terminals shows that the battery in getting some 13.5 volts with the engine running. A bit of a conundrum, to say the least . One suggestion from my mechanic friend who had worked on the car for the previous owners was that there could be a fault with the exciter wire grounding somewhere. He suggested to disconnect it at the alternator and see if the light stayed off when the engine was started. Have not tried that yet. Other than that don't have much else to go on.... Anyone else have any ideas?

Update - after disconnecting the exciter lead the warning light went off and stayed off as it should. So went back and this time loaded the alternator with everything on in the car. Got 12.75 volts. Turing off the hi-beams the voltage output went up to 13.5 volts. So now am just suspecting something amiss in the alternator itself. Could be a bad diode/brushes or a combination. In any event it is coming out on Monday and off to a good repair shop for diagnosis and rebuild. Interesting this unit was gone through a few years ago (long before we acquired the car) for a rebuild. Not that many miles put on it since then. Oh well - seems like the luck of the draw

Update 2 - Took the unit to a well respected local repair fellow near me in San Fernando, CA (USA). Main problem was that a couple of diodes went south. Should have it back tomorrow (Wed ) in the afternoon. He wants to run it on the bench for some time to ensure that all else is OK as it had lasted all that long from the previous repair.

Update 3 - Problem turned out to be a couple of dodgy diodes. And the ones in that alternator turned out to be a bit hard to source in the Los Angeles area. But all back together and installed.

Will say this - working on a XM almost makes working on a D series a "walk in the park" by comparison

Steve

This post has been edited by Citroenfan on November 06, 2015 01:34 am

[Norman]

Hi,
Should the voltage reading be at 14.1 when charging the battery 13.5 seems a bit low, it might be a idea to have a auto electrician check it over.

Regards,
Norman

[Peter.N.]

I would agree, the voltage across the battery with the engine running should be around 14.4 volts, I suspect you have a faulty regulator in your alternator.

Peter

[Citroenfan]

Agree

Unit coming out on Monday and going a shop I have used, with very good success, here in the Los Angeles area over the years. They rebuilt the starter in my 72 DS some 12 years ago (and about 130000 miles) and it is still as good as the day I installed it. As to the actual problem - could be a number of things or a combination of them. Real problem is that the unit was rebuilt by another supposedly good shop not that long ago. Will upload info on the actual problem when I get the unit back in day or so.

Steve