Issue With Ammeter Wiring

[Viper]

So, there is this lovely guide on cj3a.info about how to test your charging system. I figured I would follow the guide to make sure there were no issues there before I replace the battery. Turns out, according to that site, I have an issue with my wiring in the ammeter circuits. Here is the direct quote from the website. "Different voltage readings at the battery positive terminal and the regulator battery terminal indicates a problem with the vehicle wiring in the ammeter circuits." I have a couple questions about this. First, that's kind of vague and I'm still not very sure what the problem is or how to fix it. Second, I asked my father about it, and he thinks this result could be caused by the battery being low (which it is, and it needs replaced). I guess I'm really just asking what my course of action should be. I could replace the battery and try again, but I don't want to put a new battery in if we still have charging issues. Option 2 is to try and figure out exactly what is wrong before I put the new battery in. Only other info I can think of is that the battery terminal on the voltage regulator looked much more rusted than the other 2. Any thoughts? All help is appreciated. :)

[bmorgil]

I am not sure what the web site wanted from the process. That being said I would try this.

Start the motor hold the RPMs up to 1700 or so, and put a volt meter across the battery. The voltage should be around 13.8 to 14.7 volts on a 12 volt system and 6.9 volts to 7.5 or so for a 6 volt system. Low voltage indicates a charging system problem. If the Ammeter on the dash is indicating a high amperage to the positive, the battery is drawing maximum amperage trying to charge. It is either low or bad. Take the battery to the parts store and tell them to test it. By far a load test is the best way to judge the condition of a battery.

[Viper]

Start the motor hold the RPMs up to 1700 or so, and put a volt meter across the battery. The voltage should be around 13.8 to 14.7 volts on a 12 volt system and 6.9 volts to 7.5 or so for a 6 volt system.
Well, that was part of the test and I got the voltage I was looking for.

If the Ammeter on the dash is indicating a high amperage to the positive, the battery is drawing maximum amperage trying to charge. It is either low or bad.
That's the other thing I forgot to mention, I don't think the actual dash gauge works. It always shows 0 no matter what.

Take the battery to the parts store and tell them to test it. By far a load test is the best way to judge the condition of a battery.
I certainly could take the battery to Autozone for a test, but I'm almost certain that it's dead.

[okiemark]

If you have a trickle charger you can try leaving the charger on the battery for a day. Take it off and check the voltage. It should be over 12 volts. More like 12.5. Then check it periodically and see if that voltage drops. If it does you battery isn't keeping a charge. Sometimes a battery will hold good enough that you can use it as long as you start and run everyday, but won't hold if it sits for a week.

[LarrBeard]

"That's the other thing I forgot to mention, I don't think the actual dash gauge works. It always shows 0 no matter what."

You can test the actual gauge with a D-cell flashlight battery and a couple of wires. Get in behind the dash and disconnect all the wires from the ammeter - keep track of where they were connected. Hook a wire to each terminal of the ammeter. Connect the D-cell battery to the two wires. The ammeter is, for all practical purposes, a dead short. A D-cell alkaline battery will drive 5 amps or so into a dead short. With the battery connected to the meter, the needle should deflect up or down off zero. Reverse the wires and the needle will deflect the other way.

No deflection, bad ammeter. Don't leave the wires hooked up too long, the battery doesn't really like to be stressed like that!

[Viper]

It should be over 12 volts. More like 12.5. Then check it periodically and see if that voltage drops.
It's a 6 volt so I should hope it doesn't read 12.5 volts lol. But once again, I know the battery doesn't hold charge. I have to charge it every time before I start it. Now that I think about it, if my charging system works (which I believe it does at this point) would a fubar battery still not get a charge from it?


You can test the actual gauge with a D-cell flashlight battery and a couple of wires.
Thanks for the tip! I'll be sure to try this next time I'm working on it. If the guage is bad would it be a good idea to replace it? Or perhaps it would be better to bypass it in some way?

[bmorgil]

Viper you are on track. The correct voltage at the battery test indicates the charging system is trying to charge the battery. A battery can charge up and hold voltage, but have no current capability. by taking it out and getting it tested you will know if it will take a charge and provide current, or not. A load test is the way to find out. It might be good, just dead. Dead lead acid batteries sulfate and are quickly ruined. You must keep them fully charged. Take the battery in. Since you show 7+ volts while running, the battery is suspect. The Amp gauge may be correct. The battery may not be taking a charge.

[LarrBeard]

"If the guage is bad would it be a good idea to replace it?"

Yeah - that would be a good idea. There are only four gauges on that panel, but every one of them monitors something important to either get you where you want to go or to keep from damaging the engine.

I suspect BMorgil may have hit the problem on the head - you have a sulfated battery that won't take a charge. Pull it and get it tested. Auto Zone would love to test it for free and sell you a new battery!

[gmwillys]

Baby, non coated Tylenol, one dropped in each cell then charged, can reduce sulfated cells. This is a farmer's trick to help the longevity of a battery, but for whatever reason 6 volt batteries don't live long. I've tried Tractor Supply Travelers batteries, and some of the parts house batteries. I probably need to invest in battery company stocks, or better yet a battery tender.

[bmorgil]

I have been told these are real good products. I have a 12 volt in mine. We have a couple of this brand around. A large USA manufacturer. This link is their commercial offerings for a 50' 6 volt CJ3A. http://www.dekacatalog.com/ Look for a Deka 901MF

[Viper]

Since this post I have installed a new battery in the jeep. I've been disconnecting the battery after I'm done with it just in case. With the new battery in, the ammeter still reads zero, and I've noticed that turning on the headlights moves the meter ever so slightly. I wasn't able to try the D-cell battery test that was suggested because getting behind that panel is a massive pain and I didn't think it was worth it. I think at this point, I'm just going to leave it and hope it all works.

[bmorgil]

All sounds good. The ammeter moves from zero to positive when the Generator is charging and moves to negative if there is current draw but no "balancing" or higher charge from the generator. So normally when you draw current from the battery when the engine is off the meter reads the discharging battery and is telling you how much current "Amps" are being pulled from the battery. When the engine is running the Generator should be charging. The amp meter will read the "charging" current as positive amperage. If the engine is running and the ammeter reads 0, the battery is charged (assuming a good system). If the Amp gauge is reading negative when the engine is running and you turn the lights on, the system is not charging sufficiently. It should read slight negative amperage when the engine is off and you turn the lights on. It should not read negative amps when the engine is running with the lights on.

[Viper]

After driving it around a little bit, I actually figured some more stuff out. When the engine is running, if you pull the headlights the ammeter drops a noticeable amount. This should mean the ammeter is functioning properly, but that would also indicate that my charging system isn't working, even though my multimeter test said it was. I thought I had this sorted, but it seems I definitely did not lol.

[bmorgil]

What happens when you hold the engine rpm's up? Does the ammeter move to "+" with the lights on and the motor revving?

[okiemark]

It's normal for the ammeter to move a little when you turn on the lights as long as it stays in the plus side, you're alright.

[LarrBeard]

Another thing you may or may not have noticed. When you crank the engine, until it fires, the ammeter will wobble as the points open and close. This is a good check if some day it won't start.

[Viper]

Not sure about the higher rpm or the cranking, will check at some point. okiemark, the problem is that it's in the negative.

[bmorgil]

With the engine running at idle, it is possible the original 6 volt system may not have the ability to provide enough current to charge or balance the load. When you hold the RPM's up to 1500 or so, that will provide the generator enough speed to produce some good current. If it does not move back to 0 or "+" amperage the system is not putting out sufficient current. Keep your volt meter across the battery. Record the voltage at idle with the lights on and the engine idling, and then at around 1700 rpm. Let us know what you get. It should be fairly easy from there once a little diagnostic is done.

[Viper]

With the lights on, increasing RPM does move the meter up some, but it is still negative. Didn't have a voltmeter with me this time, but last time I tested it seemed fine. I will certainly test it again next time I can.

[bmorgil]

Negative amps won't do. Lets get that volt meter reading. It is possible a voltage regulator adjustment is required. Hopefully that's it. LarrBeard has posted some good information on this forum for adjusting the regulators. It could just need an adjustment. If the generator is not supplying enough current to the battery that could be a few things. It is possible the generator and or regulator needs a going through.