The Stovebolt Site Forums The Shop Area The Electrical Bay Battery charge problem- quick question, ongoing troubles

Hey, folks, I posted a question last week about my supposed 'starter problem' in my '51 3100 with '56 235 (12 volt system). Thought it was the starter, then after changing it, I found I had a low battery for some reason. After charging the battery, which I bought mid December '14 from Napa, I tried it, and the new starter wasn't starting it, but the old starter does fine, thus showing me that it was indeed a low battery causing the 'no-starts'. Well, last night in a local Walmart parking lot, it wouldn't start again. I got a slight click when I hit the foot starter. I ran inside, bought a cheap battery and put it in and it fired up and got me home. What I've noticed lately is that the amp meter in the truck is showing less than full charge. During the day, it seems to hover just below the center line, and last night it was down around the 1/4 mark toward the 'dead' end, both during my 8 mile highway ride to wallyworld, and also after I put the new battery in on the way home. It was night, so my lights were on. When I checked the NAPA battery with my volt meter today, it seems to be showing about 11-12 volts, though the meter may be a little off calibration. I'm starting to wonder if my generator is not recharging as it should. Also, I put a new fan belt on earlier this summer when I did some maintenance, and am wondering if it may have started about that time. My question, besides asking for all ideas, is HOW where exactly to start troubleshooting a problem like this. Does this model truck have any history of banging the battery bad enough to cause internal damage to the plates, since this battery is a good one and isn't even a year old yet? I'm taking the battery back to NAPA tomorrow to exchange it, but I don't want to keep fighting this problem all winter, since it's my daily driver now. Thanks for any help on this, guys. Lee

You lost me right there. Charged battery, new starter won't start it, old starter does? and you think it's the battery? I would be interested, if I were you, to see if the Napa battery checks good or bad. Batteries should have full charge of 12.6+ not between 11-12.

This proves it's not the battery. So now on to checking the Generator, VR, wiring....BATTERY CABLES/CORROSION.

Here are some steps to take.
1. Check battery water and general battery condition to
see if it will take and hold a charge....Load testing
may be necessary.
2. Check wiring for damage and make sure all
connections at generator, regulator and battery are
tight and free of corrosion.
3. Make sure fan belt is tight enough to drive
generator at full capacity.
4. Run engine at medium speed. Using a wire, touch one
end to regulator base and other end to a good ground.
If this corrects trouble, regulator is not properly
grounded anymore.
5. If test 4 does not correct trouble, make this test.
Connect a wire from regulator terminal marked "ARM" or
"GEN" to regulator terminal marked "BAT" with engine
running at medium speed. If charging rate increases,
replace old regulator.
6. If test 5 does not correct trouble, make this test.
Connect a wire from "FLD" Terminal of regulator to a
good ground with engine running at medium speed. If
Charging rate increases, replace old regulator.

If none of the above test show a bad regulator then
there is probably a problem in the generator itself.

Thanks, guys. I realize, after putting in the new battery last night and seeing the ammeter showing less than good with the lights on, that something else must be the matter. I was really surprised that the brand new, out of the box, NAPA starter failed (just a loud whine like it wasn't engaging, although when I took it out and pressed the switch in, the gear was definitely sliding back into position. ???) So, I figured it was in in either the generator or voltage regulator, which is why I was asking where to start the troubleshoot process.

That said, I charged the battery for about 45 minutes today, put it back in the truck and drove back down to NAPA (also in Farmington, about 10 miles from me), and told them I bought it in mid December and it's failed me twice. They were going to test it, but I told them I'd just charged it, so they just said they'd give me a new one. Took the other one back to Wallyworld and told them I didn't need it, got my money back. (Not exactly honest, but the Walton's will be ok, I think).

Thanks for the tips, both of you. I really appreciate the in depth list, Kenneth. It's too dark to get anywhere on it tonight (spent the day putting my heater back together and trying to drill out one of the housing to side panel bolts from it's nutsert. It's starting to get chilly around here at night, so I thought I could at least get that out of the way. Will check off this list tomorrow. Thanks again!

The main test for a battery is a load test to see if battery breaks down. A fully charged battery is preferable for that test. The load test is to see if a battery is good.
NAPA personnel should know that.

bartamos- I got the 'Sunday kid' who is the bottom rung of that store, and gets stuck with the bad hours. I usually wince when I go in and he's the only one there because of this. Per this visit, I didn't want them to test it and tell me "Oh, this battery is GOOD!, so you'll have to keep it." I was glad the idiot was there and just gave me a new one.

A simple "load" test: Hook a headlight to the battery. Put a voltmeter on and see if it will power the headlight and keep 12 + volts. Good post above to check the Regulator. At the battery and at say 800 to 1000 RPM 12 Volt system should put about 14.3 Volts across the battery.

Update- Last night I got ready to troubleshoot the system, and the first thing I checked was the fan belt, and it was pretty loose. I tightened it up, thinking this was the culprit, and went on to change the horn that was in it (not the original) to a bell type ooga horn that came with it. I was so sure that the problem was fixed, I worked till dark on the horn, then took the truck for a test drive. The belt tightening didn't solve the problem, so I'm going back out to do what I should have done yesterday, starting with the voltage regulator and then on to the generator if necessary. Anyway, the belt was very loose, although I just put it on a month or so ago.

BTW, I just dug found my shop manual under a pile of paperwork, and realized there is a full chapter on the voltage regulator and generator that I should have been accessing all this time. DOH!

Keep after it. You should have gone Alternator a long time ago. There is no pleasure in keeping that old charging system original. You already have gone 56 motor and 12V.

I think I traced down the problem last night. After cleaning the voltage regulator points, I tried a trick I found on youtube, which works, and found the generator is dead.
(It's a Moss video, but having had a few MGB's over the years, I trusted it enough to try it, and it worked). Thanks for the tips and help! Lee