Mysterious battery killing power drain solved

[Nate475]

When I first got my M1009 over the summer everything seemed ok. Then my rear battery took a crap on me this fall so I replaced it. In a few weeks the rear battery died again. This time I replaced the front battery and I got the rear battery replaced under the warranty. Less than two weeks later the new rear battery died once again. Each time they died they were drained down so bad that the cells were destroyed and they wouldn't hold a charge. I had my mechanic friend come over and hook up a meter to detect a power drain, and none was detected. When I took the second rear battery back the store told me that before I could return another one that they needed to check my electrical system for a short. At this point I had gained some knowledge on how to test my electrical system with a meter which was a big plus, but it wasn't solving the problem.

So I got a rebuild kit from CUCV Electric, good company by the way. They were so nice they sent me a free meter, what a deal. But I never rebuilt my alternator and here's why. After discussing the problem in depth with my mechanic friend who often leaves info out on the first discussion, he told me that when ever he encountered this type of problem that it was always a short in the alternator.

Apparently the windings or that red metal wire braided thingy that surrounds the inside of the alternator can short out. It will be a situation where you start your truck 100 times with no power draw after you shut it off. But then when ever the alternator shaft rotates to that special point where the short lies when you shut it off the power drain begins killing your battery. The only way to figure this out is to hook up a meter every time you shut your engine off until you find a power draw. This could cost you a lot of money in tow bills and batteries if you don't figure it out quick enough. The other problem is that you can't fix the alternator with a rebuild kit. So I bought a new alternator from Rare Electric off of Amazon.com for $200 bucks. They have an exact replacement for the CUCVs.

That solved the problem and my gen light no longer stays on until I raise my rpms above idle speed. So that's two problems solved with one fix. As Charley Sheen says, winning!

 

[doghead]

If you did not diagnose your old alternator, you cannot safely say what was wrong with it. There is more than one component that can fail and cause a short.

I'd bet your alt was repairable with the $40 kit you bought. I would guess your rectifier was bad.

Testing is covered in the -20tm.

Even if your windings were bad, they can be replaced as well as ever other component.

 

[Nate475]

If you did not diagnose your old alternator, you cannot safely say what was wrong with it. There is more than one component that can fail and cause a short.

I'd bet your alt was repairable with the $40 kit you bought. I would guess your rectifier was bad.

Testing is covered in the -20tm.

Even if your windings were bad, they can be replaced as well as ever other component.

Thanks for the info. My mechanic buddy told me that they don't sell the windings. Perhaps they don't sell the ones he needed for the limos that he used to work on? Do you know off hand who sells the replacement windings? I've got a full rebuild kit from CUCV Electric but they don't sell the windings. I would like to rebuild the old alternator if I can and save it for a future repair.

 

[doghead]

Before you go looking for windings, test yours first.

Try a local starter/alternator shop for windings.

 

[Warthog]

There are many companies that sell alternator components. A simple google search can supply many names. Where do you think alternator shops get their parts?

While you won't like the price, NAPA comes to mind.

Sounds like it is time to find a new mechanic.

 

[Nate475]

There are many companies that sell alternator components. A simple google search can supply many names. Where do you think alternator shops get their parts?

While you won't like the price, NAPA comes to mind.

Sounds like it is time to find a new mechanic.

I'll check into it and see what I can find. "Sounds like it is time to find a new mechanic", I've got one, me, lol. I might take twice as long but I'm a **** of a lot cheaper, lol.

 

[o1951]

Since an alternator has slip rings, not a commutator like a generator, there is no bad spot. If the rotor windings have a short, it would be present all the time, in any position.

Even with bad windings, if all 6 of the diodes are good, no power will be drawn when not running.
Doghead is correct - if your power drain was from an alternator, the problem was bad diode (s).

Glen Burnie is a suburb of Baltimore, which has lots of alternator and gen repair shops. Since you have to learn how to diagnose an alternator, the least expensive and most effective repair method would be to pay a repair shop their diagnostic fee and have them tell you what is wrong, then you fix it. Otherwise, you will shooting in the dark without night vision, and buying parts you do not need.

 

[3dAngus]

I would have just pulled the plug off the alternator, charged the battery, then plugged it back in after sitting a few days. If there was no loss of battery, you know it was the alternator. It could have been something else. There is a difference between a mechanic and an electrical tech. Anyway, nice to know you got it fixed.

 

[meyerhvac]

"Apparently the windings or that red metal wire braided thingy that surrounds the inside of the alternator can short out. It will be a situation where you start your truck 100 times with no power draw after you shut it off. But then when ever the alternator shaft rotates to that special point where the short lies when you shut it off the power drain begins killing your battery."

The red metal wire is magnet wire, magnet wire is basically bare copper wire coated with enamel. The enamel insulates electrical current from electrically shorting itself out, but allows wires to be tightly wound that make a good magnetic field.

When that coating is even partially worn off in a alternator, it is usually because the rotor bearings have play in them, causing the rotor to come in contact with them. Some of the other things that could cause the enamel to wear off is vibration, heat from over current,or poorly wrapped coil. If you really want to see what state the windings are in you can use a "mega ohm meter" This meter sends a higher voltage through the windings and more easily detects flaws/partial shorts in enamel coated wire.
Good post btw.

 

[Nate475]

"Apparently the windings or that red metal wire braided thingy that surrounds the inside of the alternator can short out. It will be a situation where you start your truck 100 times with no power draw after you shut it off. But then when ever the alternator shaft rotates to that special point where the short lies when you shut it off the power drain begins killing your battery."

The red metal wire is magnet wire, magnet wire is basically bare copper wire coated with enamel. The enamel insulates electrical current from electrically shorting itself out, but allows wires to be tightly wound that make a good magnetic field.

When that coating is even partially worn off in a alternator, it is usually because the rotor bearings have play in them, causing the rotor to come in contact with them. Some of the other things that could cause the enamel to wear off is vibration, heat from over current,or poorly wrapped coil. If you really want to see what state the windings are in you can use a "mega ohm meter" This meter sends a higher voltage through the windings and more easily detects flaws/partial shorts in enamel coated wire.
Good post btw.

Thanks for the information. The alternator is sitting in a box right now along with the rebuild parts. I'll get to it as some point. The good news is that the new alternator took care of all the problems that I had. My volt meter is in the upper end of the green, instead of being in the upper end of the yellow. My gen 1 light no longer stays on until I rev the engine. So i'm smiling at the moment. Now it's time to get the body and the interior fixed, along with an AC install and a turbo charger.