Batteries not charging

RichJohnson · Post by **RichJohnson** » Sun Feb 13, 2011 7:17 pm

M38a1, stock OEM.

My carb was in desperate need of a rebuild so the jeep sat a few months through the winter without running.

The 2HNs went dead flat. THat has not happened before, even from sitting. I rebuilt the carb and charged the batteries back up and got it running with starting fluid to dail it in.

I noticed the Ammeter was not showing a charge. I also noticed that the idle seemed to strangely go up and down on its own. I looked for vaccum leaks and found none. I figgured it may be low fuel pressure, a possible seperate problem.

Now the chargeing issue, I pulled the ground cable from the #1 battery to frame and the jeep died instantly. I assume that is logical to conclude that the jeep is not generating power from this test. (Unless with a 25amp generator and regulator this reaction is normal on a proper running vehicle)

My question is where to start looking, the regulator or the generator and how to figure out which one to replace.

Post by **wesk** » Mon Feb 14, 2011 2:11 pm

In all likelyhood neither needs to be replaced.

You need to at least invest $10 or $20 dollars in a Digital VOM (Volt-Ohm-Meter).

If a generator sits for a very long time and the batteries die then it can loose it's residual magnetism and will need to be polarized. To do this disconnect the large connector at the generator. Using a jumper wire momentarily apply 24 volts to the B pin on the generator quickly then disconnect the jumper. You can most easily hook the jumper to the battery terminal on the starter which will always be hot. Now hook the large connector back up and start the jeep and if that was the problem the VOM when connected (red wire) to the same battery terminal on the starter and to (black wire) ground should read at least 26.5 to 28.5 with the engine accelerated to fast idle. If not then continue below.

To isolate the issue to the regulator or the generator you simply full field the generator If the generator generates when full fielded the problem lies in the regulator.
To full field the generator you again remove the big connector from the generator and connect the jumper wire to the battery terminal on the starter. Connect the VOM as mentioned above. Have a friend start the engine and run it at a fast idle. Now touch the jumper wire to the B pin on the generator while watching the VOM it should read at least 26.5 to 28.5. If it does then the regulator is the culprit. If it doesn't then the generator is the culprit.

If it's the generator then the best advice is to remove it and take it to a auto electric shop. Make sure they are familiar with the Auto-Lite 24 volt generators. If they are not print the pages on the Download page for the generator and regulator rebuild and adjustments. Take them with to the shop.

If it's the regulator then disconnect the main battery to frame ground wire. This is important to reduce the risk of fire and burnt wires. Most times when the regulator sits unused for some time the contacts inside corrode and even stick closed or open. So now remove the lid of the regulator and clean the contacts by opening them a little and spraying them with a Electric Contact Cleaner and then blowing them dry. If they still look rough get a very fine steel point contact file and lightly dress them and then clean and blow dry again. Put the cover on and reconnect the main battery ground. With the generator large connector connected and the VOM connected as above repeat the running test and check readings. If the regulator is still not charging then I suggest you remove it and take both it and the generator to your local auto electric shop.

RichJohnson · Post by **RichJohnson** » Tue Feb 15, 2011 10:43 pm

Thank you Wes. I remembered the issue of polarizing the generator if its been dissconnected for a while, in the back of my mind I began to ponder if this could happend from the batteries going dead for a couple months.
I cant wait to try it if I can get a break from the rain storm that is headed in tonite through the weekend.

RichJohnson · Post by **RichJohnson** » Sun Mar 13, 2011 6:16 pm

Ok, today I finally got some peace and sunshine to work on my jeep. After fighting with it for quite a while to get it to start, I shut it off and tried to polarize the generator.

When I did, the hole in the generator plug on pin B arced like a short. I put the plug back on and started it up and tested my batteries. My Ammeter still shows neggative movement.
My batteries tested at 30v. But.... here's the kicker. I shut off the jeep and tested the batteries again, they still test at 30v. Individually they test over 15v. They are 2HN batteries that are around 2or so years old. Some time later they still test at 30v.

I kind of think my generator may be shorted out. I am unable to test a full field becuase my batteries are obviously not responsive to a 26 -28 volt test.

While my jeep idles, its idle speed moves up and down on its own. Very puzzeling to me.

Post by **wesk** » Sun Mar 13, 2011 7:13 pm

Hello Rich,

I am not sure I understand what this means:

I am unable to test a full field becuase my batteries are obviously not responsive to a 26 -28 volt test.

Batteries will read as high as 30 volts immediately after charging but this will drop the the 25 volt range in an hour or so. A permenant 30 volt reading is not logical.

RichJohnson · Post by **RichJohnson** » Sun Mar 13, 2011 9:31 pm

I kind of think that there may be something wrong with my Fluke meter now. Its reading my BB2590 radio battery at 19v when they should be around 16v charged.

The batteries in the jeep were only on while running after the polarizing for seconds. When I read the 30v I shut it off. I did not see the ammeter move to the posative side at all. It used to even at idle and I know that these batteries should be low from from sitting and running the jeep without charging. I have been cranking on it quite a bit the last couple days. I have never seen them read 30v before. Always around 26-28 while running.

I plan on bringing my work fluke home tomorrow and verify my readings. I believe my readings are suspect based on other batteries I have tested that tested illogically too high.

What do you think about the idle speed going up and down on its own?

Post by **wesk** » Sun Mar 13, 2011 11:09 pm

Usually a vacuum leak. Since you just rebuilt it the questions raised are:

1-Did you use a modern materials kit?

2-Did you get both diaphragm springs located correctly?

Have you plugged the vacuum port below the carb and tried running the engine?

If you made the connection to the generator's field pin after you connected the jumper to the battery cable then you would get a small spark there.

I always direct that one should connect the jumper firmly to the generator's field pin then tough the other end of the jumper to the end of the battery + cable at the starter terminal.

OKCM38CDN · Post by **OKCM38CDN** » Mon Mar 14, 2011 6:14 am

Rich, when was the last time you changed the battery in the Fluke Voltmeter... a bad battery there will cause voltage readings to go wild...

I have had this happen sevral times... forget to turn the meter off and the battery goes week, next time I use it it is reading incorrectly...

Hope this helps...

KB1ZQ

RichJohnson · Post by **RichJohnson** » Mon Mar 14, 2011 7:30 pm

Ok first thing, my meter. I brought home my work meter and next to my home meter the batteries read 30 and 24 respectively. So, new meter readings follow.

Engine running batteries read 24v.
Full field generator batteries read 20v.
Unfield and back to 24v.

Carb rebuild.
I used a Midwest Mil kit. I have had excelent results doing it 5 years ago and on a couple friends m38s. I have done a few now. I used 6 of those knockoffs years ago without satisfactory results.
Any way, I did notice that the springs that came in the new kit were not the same as the ones that I removed from my carb so I reused my old diaphram springs. Dont know why the springs came different this time. I was confused but passed it off as a miss pack.

I have searched for possible vaccuum leaks using starting fluid and found nothing.

I cannot get the jeep to start cold without pulling the crossover and using lots of starting fluid. It will fire right up when hot but cold its dead.

At this point, I think I am going to start over. Valve setting, timing etc.

Seems my generator is the culprit of the charging issues. Maybe its what caused my batteries to die in the first place. I checked my starter swich and there is absolutly no continutiy through it so there shouldnt be a battery drain there.

I have converted my m37 over to a 60 amp alternator with a kit. I have another kit and a 150 amp alt that I want to put in the m37 so I may move the 60 amp alt to the jeep. I also have another generator around here somewhere too. Ide like to try that one first before I go to the alternator.

Post by **wesk** » Mon Mar 14, 2011 10:50 pm

I've got the 60 amp alternator in my M37 and I love it.

Have you tried a motoring test of the generator?

RichJohnson · Post by **RichJohnson** » Tue Mar 15, 2011 9:32 pm

Yes, drove it around the first day I posted this. I had rebuilt the carb and put it on and found the batteries dead flat. That never happened before. I had to charge both of them a couple times to get them to come back. I drove it around and watched as the ammeter was very negative.

Post by **wesk** » Tue Mar 15, 2011 9:41 pm

Motoring test of the generator is when you loosen the generator belt so you can spin the pulley by hand. If she spins freely without any rougness or noise then remove the plug on the top of the generator. Connect a pair of 16 gage wires to the A & C pins. Combine the free end of this pair of wires to a singe wire preferably with an alligator type clip on it and long enough to reach the hot post on the starter switch. Now if you touch that clip to the starter switch battery post the generator, if it's good, will spin just like an electric motor.

RichJohnson · Post by **RichJohnson** » Wed Mar 23, 2011 8:21 pm

Well, I found that my spare generator has a part of the rear mounting tab busted off so the bolt hole is open and a nogo for the jeep.
I tore my garage apart and located my 60 amp alternator kit and my spare alternator and installed it. After much fussing with ether to get it to start I dialed it in and now have charging batteries.

Now if I could get it to start on its own.