Alternator Charging Issues
 

So I'm having charging issues. My alternator is struggling to charge, and can't seem to take the battery beyond 12.7V, and having more than one electrical item on at once takes it below 11V. Higher revs seems to make little to no effect.The battery is only a couple months old and I wasn't aware of any issues until the other day when I noticed a dull flicker from the battery warning light.

Now I've checked the exciter cable for continuity, and it came back with nothing. So I thought that was an easy diagnosis; however when I connected a wire direct from my live post to the alternator to bypass that there was no change; no increase in charging. All connections seem clean of corrosion, and I've also tried re-earthing the thing, to no avail.

Thing is my battery isn't running flat, there is some degree of activity from the alternator. Could it be that it's simply showing it's age? I only bought the car a year ago so I have absolutely no idea how old the alternator itself is. I thought the cause could potentially be that the battery is 100AH which is, I know, above the suggested. But I needed something to stir her up properly on cold Swedish mornings, and the battery I replaced was 110AH. Back then it ran a comfortable 14.3 whilst idling, but wouldn't hold a charge.

Are all these connected, symptoms of a failing alternator? Or is there something that I'm missing?

First: please confirm what year and motor you have.

The flickering battery light is a symptom of an alternator on its way out. It will fail slowly over time producing less and less current. I would recommend you pick up a spare alternator and put it in, take the old one out and see if that fixes the issue. If yes, then great! you found the problem. If no, then at least you have a good spare part to keep.

My guess is if this is a 2.5, 200, 300 tdi etc. then this is your issue. Best of luck

Sorry I thought I had responded to this ages ago!

It’s a 1995 defender 300tdi, I was afraid that might be the answer but you’re right about it being good to have a spare if that’s not the cause! Thanks for your response

Matt