The Stovebolt Site Forums The Shop Area The Electrical Bay battery dying

Before I even attempt to troubleshoot this. I'd like to hear some ideas. 1950 Chevy 3100 still operating on 6v. Runs great, wiring harness new, starter strong.
Generator not noisy, voltage regulator clean. The problem is it will run great for a couple of months than one day will go to start it and not enough juice to turn over the engine. The battery was old and little week so I bought a new one. Ran great for a couple months and same thing happen, not enought juice to turn over. When that happens and I plug in my battery booster. The starter turns over perfectly, I'll drive it for a few days the battery charges and the problem is gone until a month or two later and it happens again. Any ideas????????????????

how long is it sitting unused? check/clean every connection, make sure you have externally toothed star washers on all grounds and on the + cable at the starter, I'd guess a connection oxidizing, and that may be inside the starter or foot contact switch box

Bill

Check for a small drain with the key off.
Disconnect the battery cable and put a multimeter between the battery post and the cable. Start with the 10A scale then change to the 1A scale. There should be 0 draw with everything off. Even a fraction of an amp will draw a battery down over time.

Like Sears says check for a drain. Also check the charging voltage. It should be 7 to 7.5 volts. If you let it set for periods at a time its a good idea to put on a battery quick connect.

I have a similar problem on my 54 half ton. I finally installed a quick disconnect. I use the disconnect whenever I park the truck for more than a few hours. I think mine is caused by a faulty generator and a possible drain on the battery.

Recently had a client with an old Fordson tractor that killed its battery shortly after shut off.
Problem was that the generator relay was faulty and would try to motorize the generator when the key was off.

Always look for zebras.

seems like we get a lot of these type questions , suggestions are given but very few chime back in to say what fixed the problem..

must be a battery drain some where, I never could find mine so
I too installed a cut off... I t hink mine was in the Alt..

I know, yours is a 6v and dont have one... those things should be easy to find.............but
good luck with yours and please let us know when you fix the problem..

Had a similar problem with a neighbors 62 Ford unibody truck. It was the brake switch causing the drain. Not enough electrical drain to activate the brake lights.

Also had this problem. I discovered it was the quick battery disconnect, the type with the plastic knob and brass fitting that connects to the negative battery terminal. No problems since the removal.

Reading this thread and this was my first thought. With the advent of alternators and integrated regulators we've forgotten how finicky some regulators could get. A little too much moisture, a loose ground, corroded contact points, or a spring that is losing tension - all can contribute to a charging system that becomes unreliable.

As much as I agree with the idea of installing a quick disconnect switch (I have one on my truck) getting to the heart of the matter makes better sense, especially when you find yourself a couple of hundred miles from home.

I open the generator today and found the commutator dirty, brushes are good so I clean it and put it back on engine. Here's what I found so far. At voltage regulator using a voltmeter on generator pin I was getting 2.5 volts with engine running. With volmeter on bat pin I was getting 6v. I don't think the 2.5v is normal, so I cleaned the generator connection at the generator and jumpered the field wire to ground. I'm now getting 7.5V with engine running faster than idle. Are those readings OK???? Does that mean my generator is working?

Dan

Dan,

Just in case you forgot: did you repolarize the generator?

So the 7.5 volts at the battery terminal would indicate that the generator is working correctly. If this is the case then the field is not being regulated properly by the regulator. Grounding the field at the FLD terminal on the regulator would tell you if the problem is in the harness.

when grounding the field terminal, what am I looking for to indicate a problem with the harness? Will the 7.5v stay the same?

if I used a quick disconnect switch, will I have to polarize the generator everytime I disconnect?

Do you have a continuity tester?

You could put it between the "hot" lead on battery and the battery cable (positive lead in Chevrolet). Turn off the ignition switch. If the tester shows any continuity, you have a short.

If you show a short. Reconnect the battery cable and:

Either:
- place the tester between each wire closer to its devices that receives current, and check the tester.

Or:
- leave the tester near the battery (with ignition switch off) and one-at-a-time disconnect each wire near its device, and check the tester.

If there is a short somewhere, and you are lucky (and carefully methodical in testing all connections), you might find the/a short.

In the early 70s, I had a 6v VW Squareback that developed a drain on the battery. I traced it to a badly shorted electric clock.

DJRoy,
we seem to have two themes going here, one that your battery is being drained overnight and the other that your charging system is not working. I will comment on the charging system.

First, once the generator is polarized, it will stay that way.
If you grounded the field on the generator and the battery terminal on the regulator was showing 7.5 volts while above idle, then your generator is working. I specifically mentioned the voltage at the battery terminal on the regulator. Now, if the field was grounded at the generator during the test and not at the regulator, it is possible that the wire connection between the generator field and the regulator field terminal is broken. That is why I suggested doing the test with the ground applied at the regulator terminal. If you do so and the results are the same then I would replace the regulator.

Did you add any accessories recently like a after market modern radio/CD/cassette player.
If you did go to this Post
Modern radio/CD/cassette players do not shut off completely when you power it
off from the main radio/CD/cassette players on/off switch/button.
If you do not remove power from accessories switch wire the unit will continue to draw power.
If you have not added any accessories recently disregard this post.

Thanks,

I will do all those test in a day or two but here's a stupid question, this 1950 Chevy 3100 electrical is negative to ground right? Is it possible the generation is postive to ground? How to you test that?????????

You can polarize the generator either way. If it was putting out plus 7 volts then it is polarized correctly for a negative ground setup.

Here's what I've done so far. Installed ammeter in series with the positive bat cable. I had no draw whatsoever with the ignition switch key off. I did polarize the generator and here's what I'm reading now at the regulator. With the field jumpered to ground I get 7.5 - 8V at both the armature and the battery terminal. Voltage increases as I rev the engine. Now with field jumper removed I still get 7.5V - 8V at the armature and battery terminal. Is that normal with field wire removed???

That sounds like the generator is charging properly. The voltage is a little high as I would not want it going past about 7.5 volts. A fairly accurate meter is needed to make that call. There is a procedure in the manual for adjusting the voltage on the regulator. I just adjust it with the engine well above idle and I know my battery is in a good state of charge. I don't mess around with the other two adjustments unless I have a real problem.