Electrical woze

[Willy]

Cheers, I'll try and get up some point this weekend if it's sunny.

In other news, made it to work and back o_O

[andycadabra]

I've had all the symptoms of alternator failure, rapid discharge of battery, dimly flickering battery light on dashboard, and battery voltage reading less when engine running than when ignition off.
I managed to get an new alternator for £42 on eBay, from France, and it's pretty much like the old one, except that the terminals are labelled B- and B+. The terminal corresponding with the position of the new one's B-terminal on the old one is labelled D+, and the other has no label. Both the B+ terminal and the old one's un-labelled terminal have a small wire which, goes inside, whereas the other terminals don't. If it helps, the other smaller [green] wire was only connected to the other terminal by a slide on 'spade connector' which I've connected to the new B-.
I have connected the smaller green wire that went to the old D+ terminal to the new B-terminal and the B+ to the thicker cable that goes to the battery via the starter motor - can I assume this is correct? I can't figure it out.

[rutter123]

if you have a multimeter you can put it in line with the pos term and pos battery lead, this would indicate any drain on the battery with the ign off.

[andycadabra]

the battery's now had a good charge, but after putting it back this morning, the red battery light is full on, not even dimly glowing as before, and the voltage at the battery about 12.7 V whether engine running or not. I also tested between the alternator B+ and the bodywork, which gave the same reading, so presumably the wiring between the alternator and the battery is ok.
I tried disconnecting the small green lead that goes to the B-, which made the warning light go off at least, but left the voltage situation in the same sorry state. If the battery was faulty I would have expected at least the same situation as before, not worse - could the alternator be incompatible I wonder?

[andycadabra]

Hi Rutter - thanks, only just noticed your post. Excuse my ignorance but should the multimeter be set to voltage or resistance?

[andycadabra]

Tested both - resistance none, and voltage 0.02v when ignition off, 0.01-0.02v with ignition on

[electrokid]

This...
http://www.ebay.co.uk/itm/ALTERNATOR-C ... urn false;

is what the back end of your alternator should look like. This one seems to have 2 substantial connectors so that's a bit confusing. With the alternator off the car hook a voltmeter up on the volts range with the black lead to the metal work of the alternator and the red lead to a terminal - test both of them to see which one produces output when you spin the shaft of the alternator. If one of the terminal produces a voltage and the other doesn't then connect the main feed from the battery to that one and the skinny wire to the other. If you have more than 2 terminals do the spin test and connect the battery lead to the one that produces a voltage when the shaft is spun. As per my PM, ignore the skinny lead for the moment - we'll worry about that later.

[mat_fenwick]

It needs to be set to measure current (amps) but many meters have a low maximum current capability so can easily be damaged or have the fuse blown by too high a current. I doubt that's your problem though. B+ is battery positive, B- (or D-) battery negative and usually optional. D+ is for the warning light but there are other possible designations. Do you have a photo, or can you list any terminal letters present?

[electrokid]

Actually the larger connector is more obvious in the pictures on this listing...

http://www.ebay.co.uk/itm/CITROEN-BX-AL ... 5645b9217e

[andycadabra]

thanks for the tips, guys!. I discovered today that after a drive, voltage measured 14.5 V with the engine running, even though the warning light was still on. When I measured it later on it was just 12.5v but after revving the engine went up to 14.5. Although the belt doesn't look like it's slipping, maybe that's what's happening?.
As for the light staying on, I notice in the eBay listing you found that there are 2 connectors plus a 3rd one which is right at the top in a recess, a spade connector. I need to check if there is one on mine, and if so this would explain why the warning light remains on, since that might be where the spade connector should be connected to. On my old one it was connected to one of the main 2 terminals on the back (labelled D+ on the old alternator and B- on the new one, so I connected it to the B-) .
this was the one I bought:

http://www.ebay.co.uk/itm/310858068057? ... 1423.l2649

[andycadabra]

Problem solved! There was a spade connector tab at the top ready to accept mine, and now the battery light is off, and the battery is registering a charge of 14.5v all the time, though I will keep an eye on it.
I shouldn't have assumed B- was the same as the old D+ but it would have been useful if the alternator had come with some instructions or diagrams.
Still seems odd to me that it would give 14.5 V after a rev when the spade connector was connected to B-, although mostly being at 12.5v. This morning I even tested the voltage with the spade connector disconnected from B- and it was the same 12.5v. Somehow connecting it to the correct tab has meant it works as it should, all of the time.
At last I'm able to recommend Mister Auto of Lyon's alternator, which at £42 delivered, was a pretty good buy. Described as Cevam, but also bears the Valeo name. Special thanks to Mat and electrokid.

[andycadabra]

Except that that new/rebuilt alternator bought from Mr Auto on eBay failed after 18 months...
Decided to opt to go for a second-hand Bosch one from a ZX, also from eBay, for £25 delivered, and it's fine.
Complained to Mr Auto, and suggested I was due a partial refund at least, under the sales of goods act, and offered to return the alternator to their London office.
They replied asking how much I would want, and I suggested a refund of two thirds the price, and I just received a refund.

Would have liked to not have had the trouble of losing the car for a week and replacing it, but at least Mr Auto did the decent thing.
Also, It seems, in this case at least, second-hand has/would have beaten 'new'.