Charging issues - I think my alternator's about to die!

citsncycles · Post by **citsncycles** » Wed Oct 12, 2011 9:10 pm

Ok, I know it's not a BX, but hopefully this is general enough to be of use to someone else:

Battery almost went flat on the way home last night, with the volt meter showing a discharge with the headlights on.

This morning I did some checks with a digital meter and come up with the following:
at idle - about 12.4v
no change until about 2000rpm, when I managed to get a reading of 13.6v
switched the headlights on at 2000rpm and voltage dropped to 12.5v
as the rpm dropped below this, so did the voltage

I repeated the above after borrowing a voltage regulator from my mates 2CV with the same results. I've concluded that it's the alternator putting less than 100% out, but I'd love a second opinion before pulling it to pieces to fit a spare I have.

Dollywobbler · Post by **Dollywobbler** » Wed Oct 12, 2011 9:12 pm

Certainly looks low. You need at least 13v to be charging really. With 14.7 being about the maximum I think. Could just be brushes if you're lucky.

Post by **mat_fenwick** » Wed Oct 12, 2011 9:22 pm

Agreed. A '12V' battery is actually about 12.6V when fully charged, so needs a higher voltage than that to charge it properly.

Mothman · Post by **Mothman** » Wed Oct 12, 2011 9:58 pm

Mine definately failed with 'a red light'

appearing on the dash. When checked with a meter it was only putting out 11.8 volts. I would suggest that although yours is still marginally working, failure is about to occur and i think it would be wise to replace it before you think about a long journey.

Andy

citsncycles · Post by **citsncycles** » Wed Oct 12, 2011 10:06 pm

Thanks for the replies folks. I have a clean looking alternator on a spare engine that I'll fit tomorrow, then I plan to strip and hopefully repair the one I remove. As new ones (when you can find them) seem to sell for around £80, repair is definately the way to go if at all possible.

Mothman · Post by **Mothman** » Wed Oct 12, 2011 10:10 pm

Bought a valeo recon job for a BX a few weeks ago on feebay for 14 quid. Couldnt resist it at that price, will do for all my motors if needed.

Andy

citronut · Post by **citronut** » Wed Oct 12, 2011 10:35 pm

if this is a dersh (2CV) they have a seperate voltage regulator, so you need to put this into the equasion,

regards malcolm

citsncycles · Post by **citsncycles** » Thu Oct 13, 2011 1:24 pm

if this is a dersh (2CV) they have a seperate voltage regulator, so you need to put this into the equasion,

This is a GS, but still a separate voltage regulator. I still have the original mechanical one so the first thing I did was strip it to clean the contacts. I also tried it with the electronic regulator off my mates 2CV which is known to be good, with no difference.

I swapped in my spare, and while I still need to put the multi meter on it, it doesn't seem much better than the old one. I've started stripping the old (SEV Marchal) unit, and found this:

This seems to be a connector block joining 3 wires from the windings to the main output terminal. The centre nut was loose on the 3 terminals, but when I tried turning it the bolt turned too. On removal I looked underneath and found this:

So this needs either rebuilding or replacing, and I'm assuming that the alternator must be on just 2/3rds power, explaiing the low output.
Are SEV components easy to come by, and what are the chances of this bit being common to other applications (EG 2CV)?

pmh · Post by **pmh** » Thu Oct 13, 2011 10:13 pm

Is this the same unit - different view?
http://www.iat-usa.com/catalog/images/08306.jpg

not ideal location but maybe a starter!

http://www.iat-usa.com/parts.html

search the parts ca for alternator - rectifier

then look up the parts that it replaces and you come up with

possibly this? http://www.woodauto.com/Component.aspx?Ref=RTF4929

Is it a brushless alternator? if yes I suggest that you talk to woodauto.

citsncycles · Post by **citsncycles** » Fri Oct 14, 2011 12:57 pm

Thanks for those links. It's not exactly the same (it looks like it has an earth lead that mine doesn't), but it's certainly the right general shape and for the right power output range.

The spare alternator turned out to be completely dead! A mate recons he may be able to find a replacement rectifyer for me in his stock of parts, so I'm round there this afternoon.

As for brushless - that may explain why I can't find them, although I've not totally stripped it yet, any took the back of the casing off. There's 3 wires that go into the rectifier, then another 2 smaller ones, one an earth, and the other (I assume) to the regulator. all these dissapear into the alternator's guts. I would assume that any brushes would be on the end, not the middle, but then it is French! It also means that the brushes I found on Ebay may not be needed

Stinkwheel · Post by **Stinkwheel** » Fri Oct 14, 2011 1:02 pm

Those diodes can be replaced in your old unit quite easily. We stock diodes here at work that look very very similar in fact, if thats any use to you just shout.

Or having said that, i could dig through my lockup ful of G spares and see if i have an actual good part.

KevR · Post by **KevR** » Fri Oct 14, 2011 4:27 pm

One thing I've been looking at for the 2CV is modifying an alternator from a BMW R1100 bike. Small, high output (55A), reliable, built-in regulator, and cheap enough secondhand on ebay. Shouldn't be too hard to make up a mounting and swap the pulleys over (famous last words).

citsncycles · Post by **citsncycles** » Fri Oct 14, 2011 10:58 pm

Those diodes can be replaced in your old unit quite easily. We stock diodes here at work that look very very similar in fact, if thats any use to you just shout.

Or having said that, i could dig through my lockup ful of G spares and see if i have an actual good part.

Yes please! I've just tried the Woodauto site and you need to apply in writing with headed paper proving you're a trader before they'll sell you anything

Stinkwheel · Post by **Stinkwheel** » Sat Oct 15, 2011 6:37 am

Yes please! I've just tried the Woodauto site and you need to apply in writing with headed paper proving you're a trader before they'll sell you anything

Thats helpful of them isnt it. Makes you wonder why some companies limit their customer numbers.

I had a quick rootle at the lockup yesterday afternoon, typically i dont see any alternators, which means im also bound to need one soon

Anyway...

PM me your address Mike and i will get some of the diodes in the post to you

citsncycles · Post by **citsncycles** » Sat Oct 15, 2011 9:46 pm

PM Sent...

Thanks for looking through your spares for me. These external regulator type alternators seem to be a bit thin on the ground these days, and the only reply I've had so far from the various reconditioners I contacted wanted £180 exchange

I'll also be looking to rebuild the totally dead Valeo unit I have, so if sod's law works for you as well as it does me, give me a yell when you need one.

How sod's law is working for me at the moment is that this happened a month after selling my only other currently roadworthy car, and the same week I buy another motorbike project that needs collecting! I've actually been leant an alternator by a mate for now, but as he needs it for one of his cars, I need to give it back to him.