Front battery won't hold charge.

[idM1028]

I'm having some problems with my CUCV. It's an 86 M1028. A few weeks ago I was going down the highway and my headlights and gauge lights starting getting dim. I pulled into the first place I could and replaced a cracked electrical connector on the driver side alternator (it was on a black wire. I'm thinking "ground" but I would have to check out where it goes to be sure) and replaced the rear battery with a new one just to be on the safe side. (They didn't have enough of the batteries I needed to replace both.) I also checked the play in the belts for the alternators and they seemed to be fine per my Haynes manual. The truck had been running fine prior to this. Yesterday I powerwashed out the engine bay. I threw some plastic bags on the alternators as best I could to keep them from getting wet. Going down the road I noticed my "Gen 2" light wouldn't shut off, but the voltmeter would read in the green. At idle the voltmeter would drop to just between green and yellow and the "Gen 2" light would get brighter. Figuring it was maybe water in an electrical component somewhere, I hoped driving the truck enough would let the engine heat dry it out. I stopped and started the truck several times in my activites and it had no problem starting up and all the electrical accesories (lights, wipers, etc) would work fine. Today I go to start it up and. . . nothing. Not even a wait light coming on. After figuring out the front battery was dead as a doornail I swapped and fiddled with the batteries I had until I could get the truck started and immediately drove to Pepboy's and picked up a set of Optima Yellowtops. I also rechecked the belts and the passenger side alternator belt looked like it had a bit of slop and wiggle in it while running, so I tried to tighten it up as best as I could. I also noticed the belt had a few of the inside "chunks" missing. While doing this I noticed the alternator was hot. Hotter than the other alternator which was cool to the touch. I could only touch the thing for 10 or 15 seconds and I was wearing gloves. (The alternator did have a coolant hose running over the top of it.) Going home the problem seemed to be about the same if not worse than yesterday. I stopped off on the way home and let the truck sit for 20 or 30 minutes. When I went to start it up, little to no power. I jumped the front battery and got the engine started, but once I took the cable off, same problem as a few weeks ago. Luckily, I just down the road from home so I was able to get it home no problem. I've read over the FAQ's and wiki for CUCV's but can't seem to find anything that matches my problem. Any help would be greatly appreciated.

 

[Cucvnut]

woah man make paragraphs that's to much to read.

 

[idM1028]

I'll keep that in mind for the future. Go easy. . . it's my first post.

 

[Cucvnut]

its ok just a lot to take in! either your alt is bad or you have a wiring issue I would down load the Tm's from JATONKA's CUCV TM download page and look at the direct support tm and go from there

 

[Warthog]

Time to pull the alternators and have them tested. Sounds like GEN2 may need a rebuild.

 

[idM1028]

Too late. Already found that. Per the TM-

6. GENERATOR LIGHT REMAINS ON OR TURNS ON DURING OPERATION (ALL EXCEPT M1010)​

Step 1. Check engine idle speed. (See paragraph 3-25) (Should be good. Kicks into fast idle for about 5 minutes the first time I start it up for the day. Then just starts up on slow idle for the most part. I don't drive it on fast idle either.)
Step 2. Disconnect connector from left alternator (if “GEN 1“ light is on) or right alternator (if
“GEN 2“ light is on). Turn key to “RUN” position.
If generator light is not on, trace circuit from alternator connector to generator
Iight in instrument panel. (See wiring diagram F-11) If circuit is good, replace
alternator. (See paragraph 4-2)
If generator light is on, trace circuit from alternator connector to generator light​

if instrument panel. (See wiring diagram F-9)

Apparently the driver side alternator charges the front battery. (Both alts charge the rear) Could explain why the one alt was hot and the other wasn't. I would expect an electrical device that big not to get hot. I mean that's why they put little fans on them right? I'll pull the alt this week and have it tested. Might as well replace the belts while I'm at it. Cheap insurance.

 

[WARWAG]

AS you stated you said they only had the one battery. BUT you should always replace in pairs with same exact batteries. The new one will be fighting the old one and both will die an early life. Glad you found the problem.

 

[idM1028]

It was late at night. I seriously lucked out finding the place I did. I probably could have swapped in a similar battery (Same brand, similar amp rating, etc.) but what was getting me was the battery height and the way the trays are set up. I could have swapped in a similar but shorter battery and held it in place redneck style (duct tape, bungee cord, whatever) and been on my merry way, but the truck rides like a buckboard wagon as is and I prefer not to have who-knows-how-many-pounds-of-battery trying to slide around in my engine bay NOT secured with a holddown. Either way, I managed to get the truck back home 40 or 50 miles no problem.

 

[WARWAG]

Sorry. I wasnt criticizing your road side repair by any means and can see my post did indeed come off that way. What ever it takes to get you home is good enough for me. **** I once tied the sidewall of my H1 up with I think hanger wire or maybe bailing wire and drove it a few hundred miles with the compressor running the entire time. Not to many places carry 37x12.50c16.5 tires let alone Goodyears that size. I had tire plugs throw out forward and land back on my windshield a few times on that trip. I agree with what you did. Just stating that when you need to replace one battery (most people just replace the one) that both should be changed out. Glad you made it home safely.

 

[overlordofmars]

Diode pack in the alternator is shorted, you lost one of four. It happened on my military Blazer.
It makes the one alternator work like a bastard to keep up the charging demand. Thus it overheats. Alternators create AC current, the diodes turn that into DC for the demands of the vehicle. I would buy a shorted regulator but your voltage is good. When one diode goes, it makes a half wave short to ground, it's like half your power is getting shorted to ground.

To make it simple , change the HOT alternator out, or replace the diodes and regulator before you cook the windings .

 

[idM1028]

@WARWAG Nah, its cool. I held a windshield wiper that was falling off on yesterday with a piece of coat hanger. Shoot, back home farm equipment is practically held together for years with bailing wire and rays of hope.
@Overlord The more of I've looked into and thought about it, the more I suspect you're right. I'm thinking about doing a rebuild, the kits for the 27si alts are like $30. My Haynes manual for '67 to '87 GMC and Chevy trucks has got rebuild (or at least brush replacement) instruction for the 10-S1 alts which apparently were used in regular old Chevy trucks from '73 on. Would these instructions be about the same for a CUCV alt?

 

[Warthog]

The rebuild of the alternators has been discussed many, many times.

The Tech manual has the instructions on how to to it. The alternators are simular but not exactly like the civvy units. That difference is VERY important to understand. If not, you will se a great fireworks show.

 

[BigDuck]

.

great show inded

 

[Barrman]

Seems you figured out what you need to fix.

Just wanted to point out something stated wrongly. Yes, the drivers side alternator charges the front battery. However, they do not "both charge the rear". The passenger side alternator charges the rear battery.

1 alternator charges 1 battery.

 

[idM1028]

OK, thanks for the help everbody. I called up a place today that does alt rebuilds (and they do have MV experience) and they quoted me about $185 per. Apparently a place called Rare Electrical sells them for about the same price. You can find them by googleing Rare Electrical or look for "CUCV Alternator" on ebay. It also seems they sell the 24V starters. I also called up the guy I bought the truck from. He said he should have a few rebuilt ones of both varieties laying around. When I asked him the price, he said free. Thanks Rob!

 

[Cucvnut]

That's kinda on the high side for a rebuild I would look around more.

 

[overlordofmars]

I think there was a place called Colemans Surplus in Pa, had good ones for $75 each, but that was over three years ago.

I have worked in the electronics field for over 24 years, I usually get those problems right. Its this new garbage that makes me want to puke.

 

[idM1028]

Well, like I said, they guy I bought the truck from has got a couple that are rebuilt and the price is free. Can't get much cheaper that.

 

[idM1028]

@ Overlord, by the way, just checked Coleman's website. No alternators.

 

[Iceman3005]

Too high on rebuild I have a guy near me that did it for $55