Alternator Question

I,ve just had my alternator repaired after it stopped working.

However, this has raised a couple of questions and left me slighlty confused! The place where i had it repaired noticed that the rectifier terminals are stamped + and - the opposite way round to the way they are marked + and - on the outer black plastic cover! So he says he has wired it up the correct way, as stamped on the rectifier (+ is + and - is -). This means when i put the alternator back on the car, he says i should re-connect the red + lead to what will be marked - on the outer black plastic cover, even though it was connected to the terminal maked + on the outer black plastic cover before i removed it from the car!

So, basically he is telling me to put the alternator lead back on differently to before i took it off the car because the outer black plastic cover is stamped up differently to the way the rectifier is stamped under the cover, which he says is the correct way! He's had it working this way on the bench, so he is telling me to disregard what the outer cover says.

Can anyone shed any light on this as I'm confused?!

Why was it originally wired to the + on the outer casing if this is wrong and how come it worked? Because if the wire is connected to the wrong terminal on the alternator won't it just go bang!?

What is also confusing me is i have a Haynes manual, which covers the Renault 25 Turbo and this shows the exact same alternator wired exactly the same way, with the red wire connected to what is marked + on the outer black plastic cover!

I'm also being told when they had the reconditioned alternator running on the test bench i will no longer have a working battery warning light working on the dash. He tried two different voltage regulators and neither made the warning light work. This concerns me slightly because it was the battery light which alerted me to the alternator not charging in the first place.

Any suggestions? Cheers!

I replaced the voltage regulator last year. The dash light had been flickering on and off intermittently since I had the car but the battery was still charging, even when the light was on.

The new voltage reg was exactly the same as the old, apart from the fact that the two wires that go from it to the alternator appeared to be on opposite sides. The wires on both were yellow and light blue but were on opposite sides on the new one when compared to the old.

I can't be 100% sure about what follows as it was a while ago but it may give some clues:

I think I started by connecting the wires in their correct colour coding i.e. crossed over. From memory - the dash light did not come on and the alternator produced voltages as high as 16v - before I managed to dive in an switch it off. I should stress that I always had the battery/earth leads connected as per the +/- marks on the alternator cover - I did not change them around.

I then swapped the voltage reg wires round i.e. correct sides but wrong colour coding and the alternator appeared to work correctly in terms of voltage regulation but the dash light didn't work.

I then spent ages swapping the old and new reg units back and forward before I eventually got the dash light working - I think it may have had something to do with the earthing of the alternator body itself but I can't be sure as I was in such a state of panic that I might have arsed the entire alternator up by connecting it the wrong way.

I think what really sorted it was the fact that I had given in and called an auto electrician out. He insisted that that the alternator should be on the car for him to test it and so I went out and reassembled it from scratch, put it on the car and switched on the ignition. The dash light worked - bizzarre! but satisfying as I could call him off and avoid a £50 call out charge.

Hope this helps in some way, even if it just illustrates that the alternator will appear to work if the voltage reg is connected asp for elbow but watch out for the high voltages.

Thanks for the reply.

I spoke to Alpine Renault Restoration on the phone briefly this morning for some advice. I was told to buy a new one rather than repair, as they aren't that expensive anyway and having them repaired often causes problems. Also, I was told, Renault have them specially made along with their starter motors at a factory in Poland. So, I'm Guessing, maybe Renault have theirs made with the regulator wired up to match the + marking on the outside casing and it has to be this way because the outside casing is designed to fit within the confined space of the GTA engine bay. So the point where the battery wire bolts onto the outside casing is in that position so everything fits into place? I'm just guessing.

Anyway, I took my alternator back to where i had it reconditioned and they''ve tried another new regulator, got the battery light working and re-wired it so the + terminal on the regulator matches the + marking on the casing.

He's tested it on a test bench and assures me everything is working and charging correctly, so we'll see when I fit it Saturday!

Cheers!