Charging or lack there of

dbz13 · 04-23-2005, 12:37 PM

I have been scouring the forums trying to diagnose the electrical woes of my 86 951 for a while now, but I haven’t found anything quite like this. Let me run my symptoms by you folks and see if any of you have the cure.

If I start with a fully charged battery (less than year old) all the warning lights work properly. The ! and alt light light up when the key is first turned on, voltmeter a hair over 12. Start the car, the alt light goes out and release the brake, then the ! light goes out. Voltage is then almost to 14, and it was around 13 while running before the problems started. Driving down the road the voltage varies more than usual, but stays between 12 and 14. Get down the road about 5 minutes and the voltage drops to 12, and then gradually decreases from there. As if the regulator quit after it got warmed up. And I can not get it charge again after that, until the car cools off good.

Trying to fix this I just replaced the battery cables, the starter to alternator cable, and added an extra ground from the battery to the engine.

I’m thinking either regulator or alternator, leaning towards (wishfully) regulator. I replaced the regulator about a year ago (same time as the battery, surprise, surprise), but I have had to jumpstart and charge the battery a few times recently for unrelated problems. I thought that I had pulled the ground off of the battery every time I charged it, and charged it as soon as I got it home after a jump start, but I probably screwed up and toasted either the alternator or regulator. I know that I should just pull the alternator and have them checked as a unit, but this is a turbo and pulling that little beastie is no easy task. I replaced the regulator last year from under the car without pulling the alternator, and am hoping this is all I need to do again.

Maybe I should just get in touch with Iceshark and get one of his regulators to see if that solves my problem?

Mark944na86 · 03:25 PM

If you want to try the simpler things first, I'd try a new battery. I know the one you've got is < 1 year old, but it sounds a bit like the problem I was having on my S2, which I chased around for a bit, only to find that it was the battery all along.

My charger would tell me the battery was fully charged (it was holding 12V), but it seemed to get run down so that after a few days I'd have to charge it manually again. When I finally got the battery replaced, I got it checked out a bit more thoroughly, and found that it's capacity was degraded to holding a charge equivalent of about a 270 CCA battery; the battery's nominal rating was 600 CCA.

I'd never had a battery fail in a "soft" mode like this before, which was why I was convinced there was something up with my charging system, or there was a short somewhere, or some other tricky problem. But since I got the new battery I've had no problems. My dash voltage gauge does the same sort of thing yours does, fluctuating between a bit over 12V and just under 14V. Doesn't seem to correlate to any problems.

-Mark

OK, now you have to explain the picture. Who's the unhappy guy in camouflage, what is he holding up, and why is he unhappy?

SoCal Driver · SoCal Driver's Garage

Bad alternator. I take mine to a reputable local rebuilder. Never buy one off of the shelf at a chain store.

You could buy just the regulator/brushes but I bet when you get the one out of the alternator and take a close look you will see the commutators are out of whack and the brushes have worn off uneven.

ernestedward · 04-23-2005, 04:52 PM

Agree with SoCal. Sounds exactly like my bad alternator.

toolboy62 · 04-23-2005, 05:23 PM

change the regulator before you go nuts. That sounds exactly like the symptoms my car made when the brushes wore themselves down to little bitty nubs.

good luck,

nate

Ferrara_racing · 04:11 AM

The alternator on the 944 is not the strongest piece in the car. I had a problem with the battery draining for a while and it was finally determined that the ground wire on the alternator was faulty, therefore the charging was comprimised. If you don't drive the car for long periods, a battery tender can be a good friend..

And thanks for fighting for the USA, if it were up to me you would have a speeding pass....

dbz13 · 04-25-2005, 03:13 PM

Thanks for all of the responses.

Mark944na86 - The picture is me. When I posted it, I thought that it was just going to be one of the thumbnails on the left by my name. I'm don't like smile for photos very well. The thing that I am holding is the 86 Porsche sales brochure. My father-in-law was trying to buy one for me off of ebay. He just missed winning an auction for one, and emailed the seller to see if he had anymore of them, explaining that it was for his son-in-law who is in the military. The seller not only had another one, but sent it to him totally free, asking only that I send him a photo of me (in uniform), the car and the book.

Ferrara_racing - You're welcome

dbz13 · 04-25-2005, 03:24 PM

One small detail I left out before: after it warms up (runs it's 5 minutes, charging a little high), and after it quits charging enough. If you turn it off and then turn the key to the on position (not running) the alternator light is no longer working.

So, I broke down and pulled the alternator. I took it to the local auto electrical shop and had it bench tested; it checked out fine. Now the only thing left is the little wire from the alternator to the alternator light. Unless I missed something...

Does anyone have any other helpful hints given this new information? I don't have a clue where to go from here.

dbz13 · 04-25-2005, 04:25 PM

I decided to pull the regulator since I had the alternator out anyway.

I don't know how the electric shop's alternator test missed it, but the brushes are down to nubs. Here is a picture of one I just pulled and the one that I replaced last year. Last year's bad one is the one with the long brushes (it was over charging).

I gave swapping the brushes a shot, but I've decided to go with a nice fresh one from Iceshark. Does anybody know how to get a hold of him?

IceShark · 04-25-2005, 05:28 PM

Yeah, those brushes are definately worn far too short.

Got your e-mail and sent you my address.

If you are in a time rush send me your address and I get one off to you before payment gets to me.

bryanthompson · bryanthompson's Garage

That's how bad mine looked when I installed IceShark's kit. 20 years'll do that

IceShark · 04-25-2005, 07:03 PM

The other thing to keep in mind is how bad the slip rings' surfaces are. If they are really chewed up they will wear out the voltage regulator brushes faster.

If you have a lathe around, then turn the slip rings. You probably don't need to do this but it wouldn't hurt. Some guys have even spun and placed some 400 or 600 grit paper around the slip rings and straightened them out. That is not the most exact process, though.

SoCal Driver · SoCal Driver's Garage

Over charging? Like how much?

As I said before ALWAYS take your alternator to a reputable local rebuilder.

Mark944na86 · 04-25-2005, 09:05 PM

Quote:

Originally posted by IceShark
Yeah, those brushes are definately worn far too short.

Got your e-mail and sent you my address.

If you are in a time rush send me your address and I get one off to you before payment gets to me.

Iceshark,

Do those brushes look they could have worn down that far in a year? From reading above, I think he said the regulator was replaced only a year ago...

-Mark

Mark944na86 · 04-25-2005, 09:11 PM

Also, Iceshark:

Do you think my fluctuating voltage gauge could be a sign of a regulator going out? Perhaps it wouldn't be a bad thing to replace for preventative maintenance anyway...

The ones you sell are adjustable, right? How do you calibrate them, or do you send them out already adjusted to the slightly higher voltage setting?

-Mark

IceShark · 04-26-2005, 04:13 AM

The adjustable ones I sell are set from the factory at 14.4 volts and you can turn a little screw to move that up or down a max of 0.5v each way. I'd just leave it set there. The old stock Bosch were usually fixed at 14.0 or 14.1v, which was really too low to bring up the battery unless you drive the car 6 or 8 hours straight.

As far as brush wear, well they were worn down somehow within a year. That does look like a Transpo regulator from the silver sticker, tell me what numbers are on the sticker. There was a bad batch of Transpo regulators made that had premature brush failure - as in the brushes wearing out too quick. If not that then I would suspect the slip rings are not in the best shape and chewing up the brushes too fast.