brand new Alternator Smoking Hot

[Josie]

Hi All;

Long time no chat.:)

I have an older 83 Cutlass supreme as a daily driver (RWD, 2bl Carb); no voltage gauge just the dummy light.

For about a month or so the charge dummy light would come on and then go off. I tested the battery each time for voltage and it would consistently give out a little over 12.6 volts and 13.4 or so when the car was running. So I thought it might be just the light but decided to do some easy stuff to rule it out.

* cleaned the positive and negative battery terminals (side post)
* Cleaned the battery cable ends themselves
* Cleaned the 2 ring connectors on the back of the alternator
* Cleaned the plug and leads on the back of the alt
* Cleaned the engine ground (it bolts to the AC compressor bracket) Both cable end and surface
* Cleaned body ground (both cable end and surface)
* Replaced the Alternator V belt (Old was due)

So after a long drive this weekend (all this was done prior to the drive) I came home, noticed my signal lights and such were running really slow. Parked the car, and when I went back a few hours later, car would not even turn over. 🙁

So since the battery was only about 6 months old, the inevitable all pointed to the Alternator. So off to the part store I go and I bought one. I got it home, bolted it up, and tested my battery before starting. I had about 11 Volts in it.

I started my truck to boost the car and ran my jumper cables. I went battery terminal to terminal and was getting no charge. (I hate side terminals! :angry: ) I instead took the negative cable off the battery and placed it on the engine ground. (the AC bracket). Couple second later the car fired up.

Seconds later I could smell electrical burning smell. then I started to see smoke. :ohmy: I then shut the car off, and still saw smoke. I disconnected the negative post right then and let the Alt cool. (it sure got hot after only 20 – 30 seconds of running!)

So I have never had this issue that I can recall. Several websites say this happened because the battery needs to be charged (not boosted) because its low the new Alt was working overtime. But I am shocked I guess because the I have drained my batteries to near nothing before but never smelled or saw that before. And again it was showing 11 volts when I started it.

In all, is there something I did wrong here? Is my new Alt cooked? What the heck is causing this?

The only connectors on the alt are the 2 wire connector plug and 2 ring leads. The ring connectors were on the same rear post on the old Alt. One ring comes from the positive battery cable, the other, a short link from the bald connector.

There is what can see, a second post, on the new alt and my internet searches tell me this is optional negative ground.The old one did not have one and I do not have a cable running to that area.

My searches also told me I should not have boosted the car but Charged the battery first instead. Boosting caused the Alt to work too hard. This is what I am doing now but again, this doesn’t make sense to me. If a Battery dies and you get boosted, how is that different then this?

In all, I have had a warm smell from a new ALT before (or any new electronics) but this seemed like a fire hazard even with the car off.

Any ideas?

Topic

[Richard Kirshy]

The way I was taught to jump start a car with a weak battery was to:
Hook up the jumper cables.
Start the primary vehicles engine and let it run a few minutes at a raised idle.
This will allow the weak battery to recoup.
Then attempt to start the vehicle being jumped.

A standard alternator is not designed to recharge a dead battery.
That will put a excessive load on it.
Given the quality of today’s replacement parts, it would not surprise me that attempting to allow a alternator to charge a dead battery could well damage it.

[Josie]

Thanks for your reply. I am far from a pro but never had this issue. I was thinking, even though there was 11 or so volts on the battery, there might not be much amps in there left. Hence the brand new alt started life “given-er all shes got captain!” and it was overloaded trying to catch up.

I have taken the battery out and placed it on my trickle (2AMP) charger for the night. Its almost charged now and when it is I’ll check the amperage to see how it compares to the rating. I’m also going to recheck the alt belt in case its too tight.
I guess I could have been abusing alternators all my life with my methods and did not know. Just hope the charging system is not messed up because of this. 🙁 If this should turn out not to be the cause, any other thoughts where this could be coming from?

[Richard Kirshy]

My suggestion would be have the battery load tested and the alternator also tested for proper output.
A good battery should read 12.6 -12.8V @ rest at reach acceptable amperage draw.
Normal charging voltage should be ~ 1v above resting voltage under load.
Charging amperage will be dependent on the specific amps / rpm rating for your alternator.
Certainly not higher than 14.5 – 14.8V, past that you’ll cook the battery.

[Mike]

My guess is that you may have gotten a duff alternator right out of the box. Sad to say, but it’s an all too common thing these days.

My checkered history of jump-starting dead cars goes back to the days when we used to make the negative connection by having the chrome bumpers of the two cars touch, (definitely not Starfleet approved), and I’ve never seen an alternator overheat.

If you are 100% sure that the unoccupied stud is a ground terminal, it might be an idea to run a ground wire from it to the engine ground. If you haven’t already done so, carefully check the existing alternator leads along their entire length, just in case the insulation might be damaged and things might be grounding out somewhere. (Perhaps your discharged battery and occasional warning light are due to intermittent grounding/shorting out.) Doing so might be a bit of a chore; engine bays of that vintage tended to be a spaghetti factory of wiring and vacuum lines, but the effort will be worth it, if for no other reason than your peace of mind. That’s a nice car you’ve got there, and it would be a shame to see it go up in smoke.

[Josie]

UPDATE:

* last night I charged the battery on the 2AMPS setting for 24 hours and was getting 13 Volts on it tonight:).

* I disconnected and checked the leads on the alt again, they are all good.

* I re tightened the belt and its in good shape. (its a new belt)

* I put the battery and in and she fired right up fine.

* I got out of the car to watch/ smell for smoke and nothing came. 🙂

* The Alternator was cool to the touch after running it for about 5 minutes.

* The Voltage on the battery was about 14.5V 🙂 while running

* In all, I’m going to keep a close eye on my battery and Alt over the next week or so and test voltages often. Hopefully the “cooking” last night didn’t do permanent damage.

* Other sites mentioned that when your car dies from ALT failure, your battery has been depleted badly as the car has been working from battery only for quite some time. It said You should always test and charge the battery on a charger and then swap the Alt. OR the new alt will “kill itself” trying to charge the battery. It “makes sense” but as Evil-i, and nightflyr said above, jumping a battery from dead never caused the Alt to act like that before. SO strange! I won’t argue with results, but still. There must be something magic about electrical stuff that I just don’t get:-D

[Richard Kirshy]

Glad to hear it’s working. 🙂

[Author]

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