Mystery current draw

[kevtherev]

Ah bad luck mate
worth a try though
I would have your alternator refurbished..much cheaper.

Ask the guys doing it what the problem was.

[CJH]

Thanks Kev. Yes, definitely worth a go, and I appreciate all the suggestions I had. I've found a place online that's not far from me, so I'll see what they say. At least they won't have to quote for a new regulator - I've got two good ones they can have for the refurb

I'm definitely going to try and find out from them what the problem is. Having looked a bit at alternator schematics, I reckon it must be some significant failure inside - perhaps a melted/shorted winding, or a fried component that's become dislodged and wedged against the case. As far as I can tell, a failed diode would just affect the rectification, but wouldn't create this kind of short. I'm tempted to pull it apart myself, but I don't want to risk adding to the refurb cost!

[300CE]

Not sure if this is any help at all CJH, but here's a post to the issue I had with my alternator. Wasn't a mystery draw, but the battery light was coming on although it was charging ok. Good luck with it anyways:

https://club8090.co.uk/forum/viewtopic.php?f=39&t=119727" onclick="window.open(this.href);return false;

[CJH]

Interesting - that's the sort of internal failure I'm imagining. Was yours the 45A version? Was it hard to get apart?

[300CE]

Interesting - that's the sort of internal failure I'm imagining. Was yours the 45A version? Was it hard to get apart?

It was pretty simple to open up, however, I left it to my mate to repair it as there's a strong possibility I would've broken it! Not sure whether its a 45A - can you tell from this photo:

[CJH]

I took my alternator to the local alternator hospital and after an overnight stay the patient has made a full recovery. It was a blown diode apparently, so after replacing that I'm pleased to report that the electrons are once again flowing in the right direction. The medical bill wasn't too bad - £35+VAT in total, which included replacing the bearings. And the old regulator was also quite healthy, so now I have got a spare after all.

I know that the blown diode was my own stupid fault. I had connected a fly lead to the spare live terminal on the back of the alternator, and then attached my timing gun's croc clip to that fly lead. Of course, when I started the engine the croc clip slipped off from where I'd balanced it and shorted to earth. Now that I know the damage that can be caused by shorting that terminal though, I've taken steps to make sure it doesn't happen by mistake. That terminal is slightly proud of the alternator housing, and although it's extremely unlikely it seems possible that it could be knocked and bent, or shorted, with a clumsy spanner.



My solution:

[300CE]

Top stuff, glad you got it sorted & for a good price too

[kevtherev]

well as I said it was "either or"
thats what diodes do though..protection for the coils

[smavan]

Found my mystery intermittent current draw, starter motor for me.
went for a drive today and when I came back the meter was showing 14/15 amp draw, it was previously 00.
Disconnected fuses in turn then alternator, still showing a draw.
removed starter positive wire and meter was 0.00 looks like a new bush and maybe a new starter.