Battery Drain...Problem

[82ABNMP]

Yes it can. One of the diodes in the diode trio can go bad, it can still charge, but it will have a draw and kill a battery with the key off. It(the alt) will even test good on a tester.

Same thing can occur with the rectifier.

I feel this has been your problem all along.


Spend $80 and rebuild both alts, and you should be good for a long long time.

Yep, DH I think you and Joe are correct.

David

 

[RodUSMC1962]

How about a battery cut off switch?I had the same problem with my chevy snow plow truck, had checked by two of the supposed best mechanics in the area, coud not find the problem. New cut off switch no problem in two years.Just put on battery didn`t go to the cost of in cab.

 

[MarcusOReallyus]

That will cure the symptoms, but it doesn't solve the problem. If there's a drain that shouldn't be there, you have an electrical problem somewhere. Hiding it that way might get you by for a long time, but eventually it's likely to bite you, and it might bite hard.

 

[82ABNMP]

How about a battery cut off switch?I had the same problem with my chevy snow plow truck, had checked by two of the supposed best mechanics in the area, coud not find the problem. New cut off switch no problem in two years.Just put on battery didn`t go to the cost of in cab.

Yes, thanks I have thought of that and may do it after I exhaust all efforts to solve the problem.

David

 

[doghead]

There are problems with that on CUCVs. We've gone over this before.

I do not recomend it.

 

[MarcusOReallyus]

A battery switch is not solving the problem, it's just hiding it. That's just not the right way to go.

 

[82ABNMP]

Roger that. I am first going to rebuild both alts.

David

 

[bshupe]

Im leaning towards the Doghead solution and just order the parts and rebuild my alts. I know me and the truck will be better for it no matter what and likely it will correct the battery drain Im dealing with. Im just dying to know what the problem is though and I dont like just throwing parts at a problem.

Now that Im pulling the neg cable when I park I have noted quite an arc when I put it back on in the morning.

By the way, is it appropriate for me to be posting on this thread or should I have started my own? I guess I was thinking that since this one was active I would ask a couple of questions but now it seems like there is two threads in one now. I apologize for this, it was not my intent and Im glad to go start my own thread if that would be better.

 

[bshupe]

One other quickie.... On that two wire plug on the back (power/exciter) if I were to try and clean all of that what would you use and am I concerned for no reason about washing gunk down into the alternator? It seems like just spraying a cleaner there would be a very foolish thing to do just looking at it.

 

[MarcusOReallyus]

There are electrical contact cleaners that are made for that kind of thing. Most hardware stores carry it.

Don't know if you want them inside an alternator's bushings, but they won't hurt anything electrical.

 

[bshupe]

I was more concerned about what the cleaner would remove than the cleaner itself.

 

[MarcusOReallyus]

If it's a contact cleaner it's safe for the usual plastics that are used in electronic devices.

 

[Braunchitis]

You are correct.

Now the challenge is, to find out what is creating the draw. You don't need warm wires to have enough draw to kill the batteries overnight.


Here's a quick test you can do if you have a test light:


Disconnect the batteries. (Leave the ground in place.) Now connect a test light to the + terminal of the battery and the cable that should attach to it.

I'm betting it will light up. Maybe dimly, but it will light.


To find the problem, you are doing to have to start disconnecting circuits one at a time. When you get the right one, the test light will go out.

OR, you can use a voltmeter the same way. When you get the right circuit disconnected, the meter will go to 0 volts (or pretty close).

Hi all,

I'm having a similar problem with my M1009, and was hoping I could please get a little help. I'll try to keep this as short as possible: The day before Christmas, truck would not start, acted like batteries were low. Got batteries tested at Sears, they said both were bad, and they were 4 years old, so I didn't think much of it and bought 2 new batteries. I put them in, truck started up fine, got home (~70 mi away) for Christmas. Drove back down a couple nights later, and the truck wouldn't start the next morning - seemed like low batteries again. I checked with the voltmeter and had 12.7V on the back battery, and only 10.4V on the front. I suspected based on other threads here (http://www.steelsoldiers.com/showthread.php?54292-CUCV-alternator-symptoms-diagnosis-and-fix) that maybe the driver's side alternator had a problem, so I took it apart and checked the diode and rectifier. They seemed fine, but I double-checked with a reputable shop, who also said they were fine. I put it all back together and hooked it up. With only the front negative battery terminal connected, I put a voltmeter between the disconnected front positive battery cable and the front positive battery terminal. I got 10.4V on the meter. I disconnected a few things, but nothing changed, until I unplugged the 2-prong plug that fits into the top of the driver's side alternator. Then, the voltage slowly started dropping from 10.4V to close to 0V. So, if the diode and rectifier are OK, could a bad regulator be a cause of parasitic drain? Or is there something else you guys recommend checking? Any help would be greatly appreciated.

 

[doghead]

Just replace the internal parts.