Evening all, Is there a way for a novice like me to test an alternator with internal regulator to tell which part of it is goosed? That's presuming this is an alternator with internal reg? The background: My battery's been draining and stupidly I bought a new battery before tracing the fault (it's the stereo, but that's a whole other thread). We used the van once then parked it up for a couple of weeks and, of course, when I tried it the other day the new battery was dead as a dodo. I charged it all day yesterday and overnight but when I checked it this morning the battery was only reading 10 and a bit volts. I needed to use the van so jump started it and bimbled off on my merry way. Came home and thought I'd check if running the van had charged the battery any more. I did it while the van was running and got a reading of 17v before the meter went blank. I then noticed that the battery was hissing. Putting the meter across it after unplugging it, it read 12.7 but started to drop straight away. So, from a quick read on t'internet, it sounds like the battery's been overcharged and that suggests the regulator but all the advice I can find on testing the regulator seems to be for external ones. I'm just wondering if there's a way to confirm it is the reg before I rush out and waste £30 on a replacement then find out it wasn't the problem.
Get yourself a new battery and regulator, anyway. Then you're sorted. Don't run the alt with the battery disconnected.
It'll be the reg... the windings in the alt are the simple bit Plus the 17v was the giveaway... You should never see more than 14.8v... And likely as not, your new battery is buggered too!! The hissing was probably the fluid being boiled off
Fingers crossed you've not done too much damage to other parts. I had a new alternator do this. It fried several components like coils, points, condenser and ignition switch. Funny enough the regulator was fine but was replaced as a matter of course.
Thanks guys. New regulator it is then, and my second battery in as many months. Quick secondary question: there are three wires coming off the two terminals on top of the alternator. One terminal's got a spade connector with a thin red wire which has been spliced into a blue one, i presume this is going to the dash light. The second terminal has two wires attached with a nut. A thick red and white, which I'm guessing is the battery one, and a thin black one. The black on disappears through the firewall with the others but is completely worn through. There's no core left, just the rubber casing holding it together. Any ideas what it is and if it's important?
The blue goes to the dash light the red sounds like a trigger wire for a relay (spit charge) big red to the battery via the starter motor Black no idea but sounds dodgy i would leave it disconnected and see what doesn't work
The black wire could be to do with the diagnostic plug. If it is then its no loss not having it connected but I'd want to investigate it first. Can you get a picture??
As Birdy says, worth finding out where the black one goes. Also the spliced red one, just to make sure it's only connected to the blue alt warning light lead. Changing the reg is pretty straightforward.
I'm away from the van for a couple of days but I'll get a shot of the black wire when I get back. Sorry, I wasn't clear about the red wire. The blue wire's been cut short and the wee red one from the alt has been butt connected to it. It doesn't go to anywhere else and the dash light works so I'm guessing that's all that one is.
Finally got a chance to get some pics of the random black wire. It starts here and goes like this: I think Birdy's diagnostic plug theory's probably right, certainly it must have been like that for a while and the van seems to have been fine. Now just waiting for the replacement reg. And a new bleeding exhaust, but that's another story.
Make sure the black wire goes somewhere, and isn't just dangling. There's unfused 12V on it, which could cause some pretty sparks
