Charging problems.

[theprof]

Hi all,
My S1 has a charging fault that is proving to be a bit of a headache. After taking out and refitting my gearbox (leaving the engine in position), and with everything back in place, on first turn over, the volt meter shows no charge being produced. The battery charge light stays on. A volt meter across the battery at idle shows a steady 12.3volts and at 1500 to 2000 RPM no change.
The obvious answer is the alternator is at fault or the battery has dropped a cell and will no longer accept a charge. But after exhaustive testing and replacing the battery with a donor one and replacing the alternator with the correct one from another donor car I still have the same fault. I have cleaned and replaced the washers, nuts, terminals and conections in every place I can find them on the earthing points, but to avail. So its time to work backwards.
Page one of two, the wiring diagram in the 'bible', shows a component between the alternator and the volt-meter, it has the symbol of a circle. Brown yellow in, green out. Does anybody know this, an inline fuse might make sense, but it could just be a weird symbol for a lamp. Any ideas, as usual, would be most helpful.

[Penelope Stopit]

You are correct, it is a lamp

Brown/Yellow is the warning light wire from the alternator to the cluster warning light

Green is a fused ignition supply to the cluster warning light

Have you possibly trapped the alternator Brown/Yellow wire?

[GreenV8S]

Do you see brown/yellow at the alternator? If you disconnect it at the alternator end and switch the ignition on you ought to see battery voltage on it when the ignition is on, and the no-charge warning lamp should not illuminate. This proves that you're looking at the correct wire and that it is not grounded anywhere.

If you get different behaviour, either you're looking at the wrong wire or you have a wiring fault, probably a short to ground given that the lamp is illuminating.

[theprof]

Thanks lads, there is good continuity front to back on the brown/yellow and when disconected from the alternator the no charge light does not illuminate. Still cant figure why the system does not charge

[GreenV8S]

theprof said:

Still cant figure why the system does not charge

Have you given it the requisite good rev after starting up? You mention 2000 rpm, but it might need more than that.

[Penelope Stopit]

theprof said:

Thanks lads, there is good continuity front to back on the brown/yellow and when disconected from the alternator the no charge light does not illuminate. Still cant figure why the system does not charge

Ok. As long as there is a good pos and neg to the alternator it should put the warning light out and charge, very likely to be a rectifier fault (diodes) and if not it is likely to have a faulty stator

[Maffe]

I don’t think my s3 start charging until the engine hits 3000 rpm, then it charge in idle.
Btw, have you connected the ground cable on the gearbox?

[theprof]

The ground / earth cable, gearbox to chassis was my first port of call, as when the gear box was out, I decided to change it. Also, when stripping down the alternator I tested the thing to death and the rectifier and diode pack came back ok, well within limits. As did the rotor, stator, brushes and regulator. The alternator earthes out through the its body, through the clamp, engine block and down to the gear box. Even fitted an auxillery earth and still the same fault. Driving me

[Penelope Stopit]

Are you able to post a few images of the alternator?

[Blue 30]

Why not try this... As you have nothing to loose etc.
Buy/find/steal a good quality warning light bulb holder (Lucas).
Not one of those crap cheap integral pea bulb warning lights.
Fit a good quality 2.2 watt bulb into the Lucas holder.
Fit x2 flying leads to the bulb holder.
Test it, across the battery
Then remove your brown/yellow wire from the alternator.
Attach one of the flying leads to the alternator.
Connect the other flying lead to the battery +Be
The bulb will (should) now illuminate.
Start the engine & blip the throttle.... Fingers crossed, the bulb goes out.
Turn off the ignition & quickly remove the flying lead from the battery, as it can back feed !!
If it has eliminated your charging fault. Then you now know where to place your efforts.... IE. Onto the cars wiring and in situ Ign bulb & holder.
If it hasn't, you've lost nothing other than an hour of your time.
TerryB

[DamianS3]

Maffe said:

I don’t think my s3 start charging until the engine hits 3000 rpm, then it charge in idle.
Btw, have you connected the ground cable on the gearbox?

So you have confirmed its not just this?

Apologies cant see a confirmation in the above text.. but im a bit bleary eyed this morning.

Damian S3

[SS2.]

DamianS3 said:

So you have confirmed its not just this?

Apologies cant see a confirmation in the above text.. but im a bit bleary eyed this morning.

You and me both then - I was thinking the same.

[DamianS3]

SS2. said:

You and me both then - I was thinking the same.

To be fair and give due credit mr GreenV8S mentioned it ages ago..

Mine doesnt actually have this feature but did when i had the ford engine.

Damian S3

[Maffe]

DamianS3 said:

To be fair and give due credit mr GreenV8S mentioned it ages ago..

Mine doesnt actually have this feature but did when i had the ford engine.

Damian S3

Missed out on that one :P

Had to take the 20 min drive to my s3c today just to check this thing out
s3c idle, then rev up over 3000rpm and then idle again
To be honest my father visiting us this weekend and he wanted to take a last look for the season.

Hi sends his regards to all the piston heads he know here

[theprof]

Well, after a day battling the problem I have a result. 18 months ago I soldered new connectors onto the ground and power wires as part of an overhaul of cabling under the hood, then heat shrinked everything. Out of desperation I removed these today, just cut them off and re-trimmed, tinned and using new terminal ends and heat shrink, put it altogether. Oh, and a different solder, a leaded one I new I had (somewhere)!
Hey presto, a propper charging circuit. Now it could have been a coincidence of course, or a case of 'tin pest'. I would hazard a guess and say 'tin pest' as I am almost certain the solder I originally used was a lead free one. Tin is weird and under the right conditions it can turn from one type to another and quite literally rot joints. Tempreature has alot todo with it as well and we have had, in the last eighteen months a very cold winter and a very hot summer. Anyway, all sorted. Thanks to those who offered advice.

[Penelope Stopit]

Good find, good fix

[GreenV8S]

theprof said:

I soldered new connectors onto the ground and power wires as part of an overhaul of cabling under the hood

What sort of flux did you use? It can be very difficult to clean inside a connector after soldering and I doubt many people would bother, so an acidic flux can result in a nice corrosive mess.

[phillpot]

Here's what you need ............... clicky