WallyP

Another factor - the regulator apparently has temperature compensation, and is designed to not charge as much when it is hot. Doesn't work well with two hi-amp fans on the A/C in really hot weather...

Bret928

Ok here is what I found.

Well as mentioned before the shop I took my car to found that the Alternator was indeed bad and was replaced it. But when I got the car back from the shop I noticed that the voltage gauge was still reading low. Because it’s an idiot gauge and not a real meter – I hooked up my voltmeter to better read the true voltage. What I found was pretty much the same as before I took her to the shop – at idle it still read low at about 10.5-11.5Vs and as before it didn’t get much above 12Vs until I got over 2000RPMs.

But just as I was about to call the shop to tell them I was going to bring the car back in – the car abruptly died while I was test driving it monitoring the voltage! Dead no power at all – not lights, emergency flashers – nothing!

Because I hadn’t had the car back more than a half an hour – I called the shop and had them come and pick it up. What we discovered with they removed the battery cover was that there was an auxiliary wire (probably to the car alarm no longer used) that was shorting to the battery cover! Once the cover was removed – power came back right away. Now I’d removed the battery cover a couple of days before the car was taken to the shop, so I know for a fact that the battery & that wire was secure and was orientated in line (horizontally) with the battery terminal – but when we removed to perform the road side jump – the wire was orientated strait up!

Anyway we the old girl started with the jumper and they took it back to the shop. I called the shop manager to try to explain what I’d seen and that I was extremely upset. He tried to tell me that they never disconnected the battery when they serviced my car and that the charging system was working fine according to the tech. I said – you mean to tell me that when replacing an alternator they don’t disconnect the battery? Every manual that I’ve ever read that is one of the first things that should be done “before” any work is started.

With that comment the shop manager had nothing more to say other than to say that he’d try to figure out what was wrong and would get back to me when he knew more. Well the next day he told me that the battery was bad and that the new alternator was also bad and needed to be replaced. Now I know the battery was pretty old so I agreed to pay for that to be replaced but asked why they didn’t check that when they originally got the shop? He didn’t have an answer. He also tried to tell me that the battery wasn’t secured properly and was moving around in the battery box. But backed off of that when I reminded him that I’d been in there prior to the car going into his shop and it wasn’t loose.

Anyway long story short the battery needed to be replaced as did the “NEW” Alternator that was replaced under warranty. And the charging system seems to be working fine now but I suspect that the shop (or the tech) was trying to cover up their mistakes. The only good news is that they didn’t ask for any money for the return visit (although they tried) except for the cost of the new battery. But that goodwill effort was a day late & a few hundred dollars short.

How I don’t know for sure but I suspect that it wasn’t their intent to rip me off from the start or if the shop just is filled with a bunch of bungling idiots.Whatever the case I seriously won’t be giving that shop any of my business ever again.

Tenshieternal

I have some of the same issues in my '84. I tracked down any faults and fixed them, put in a new alternater and lastly got a new battery and it still only generates around 11.5 volt at idle and around 12.5 at 2000 rpm and atlough this has been maintained with some load I didn't think this was right and this thread confirms it. unless there is still a shot that I haven't found, but there hasn't been a drain on the battery thus far.

Now this may seem like a silly idea but what about changing the pully size to create a 3x rotation as a way of increasing out put?

heinrich

it's why i do my own work

Bret928

Normally do my own work too. But I'd been really busy of late with work & family issues, so I mistakenly figured I’d allow that shop work on it for me as they helped me with my MG when I first got it. However that was almost 8 years ago.

SMTCapeCod

Now I'm not saying this is the -- or one of the -- 'main culprits'....but I noticed significant (indicated) reduction in load on the alternator and signifcantly better and more uniform performance lights, blowers and such after I replaced the entire positive battery cable with a larger diameter, low resistance unit. Wasn't the terminal, it was the cable. Just something to bear in mind, you know how we all dig this WYAIT stuff...

auzivision

"WallyP Another factor - the regulator apparently has temperature compensation, and is designed to not charge as much when it is hot. Doesn't work well with two hi-amp fans on the A/C in really hot weather... "


Now this explains what my car is doing. When things start heating up, the voltage falls under 12. Otherwise everything is fine (12 to 14) and not too dependant on RPM.

It was doing it again yesterday and I thought maybe the efficiency of the alternator was falling off because of the heat. I didn't realize that this was by design I presume to save the alternator or reduce the heat build up under the hood.

Thanks for the pointer Wally!

Alan

You may want to verify your alternator cooling hose is on right - if not the regulator may be heating up more than needed...

It should not get too hot under normal circumstances to make much difference unless you are heavily loading it under extreme conditions.

I'd still think you maybe have an alternator/regulator problem - unless it only happens very occasionally....

Example of extreme - quite discharged battery, car already hot - full fans, AC and headlight on in 100F+ heat (like a Phoenix summer night)...

Alan

Alan

I don't really understand how this would help...

A fault in the battery +ve cable would seem most likely to show up first as a major starting problem. When you start the car that cable has to conduct maybe up to ~500A - thats a pretty good stress test and if the car will still start - I would imagine itsshould be fine.

Once the car is started the battery +ve cable is typically only used to charge the battery... power from the alternator powers everything else directly.

I do think these cables sometimes fail - but its usually the ones that flex (ground strap) or have compromised insulation and see weather - esp road salt (which can certainly be true of the +ve cable) - and no start is the usual symptom.

If you replaced it with a larger cable - that may help starting a bit as will having clean fresh connections all around.

Improving the connection between the alternator and starter especially could make more of a difference.

Alan

SharkSkin

H, thanks... it's good to be back.

Bret, if you had a short to ground while the car was running, that almost guarantees blown diodes. Also, there is no need to get anywhere near the battery to disconnect it. On early cars like mine, the ground cable is in the spare tire well, though the spare itself need not be moved to disconnect it. Later cars have the ground connection under the tool cover. So...

No, they did not need to pull out the spare tire or open the battery cover to disconnect the battery. If the guy really knew sharks he might have pointed this out to you.

They might have dug in there anyway to do a load test which generally involves connecting a load across the battery terminals.

The loose battery and stray wire indicate that the tech isn't all that sharp. The interactions with the manager indicate that either the tech lied to the manager or they don't talk to each other much about the details. Whatever the case may be... I for one would think twice before leaving my car at that shop.

Alan

Yeah Dave - welcome back - move all done? Porsche projects back on the front burner?... or reprise of Garage Mahal (Rev 2.0..) first?

or still painting, unpacking etc....

Alan

SharkSkin

Move is done, but the list of honey-dos is huge. Most painting & unpacking is done, but there's probably 1/3 left to go. It seems that every area has needed some big project completed, or some annoyingly convoluted chain of dependencies. For example, my truck decided to start having ignition problems... once that's resolved(I think I'm there but need to drive it around), I can get a smog check. Oh, but I blew out a muffler due to backfire while I was wrestling with it -- need to fix that for smog. Once that's done, I can get tags. Once that's done, I can get a load of gravel. Once that's done, I can build a shed. Once that's done, I can move some stuff out of the garage. Once that's done, I can begin building cabinets, putting in electrical, etc. That's just one area; everything has been that way it seems.

I am finally getting around to starting on the garage a bit, though most of that's still in boxes. I've started insulating it though. So it's kind of a mix of all of the above.... Small tweaky projects are still back-burner, since I don't really have a workbench at this point.