Ammeter Generator Question

[athawk11]

Until a recent shake down at the Colorado Fall Colors tour, upon starting the Jeep, Ammeter would read in the positive then fairly quickly drop to '0' and stay there.  Now, at start it reads positive and stays positive for the balance of the Jeep ride.

Do I have a problem?

New Walcks wire harness, old 12v generator and regulator. 12v battery is a couple years old.  All other electrical performing as it should.

Tim

[RussellL]

Use a voltmeter to check the voltage at the battery while the engine is running above an idle.  It should be running between 13.5 and 14.2 volts.  Could be that your regulator is keeping the generator too high, overcharging the battery.  

[Carls_jeep]

Your could have a loose connection or defective generator or regulator and checking the voltage output is a good way to find the issue.

[athawk11]

Thanks for the thoughts fellas.  I was beginning to wonder if anyone had an idea.  Perhaps I didn't write a very good question, but once Russel mentioned a test at the battery, I started to work through the issue.  Turns out, my battery is the issue.


I tried to start it yesterday.  The starter turned over, but at a very slow pace, until the battery completely gave up.  I charged the battery overnight.  The next morning, my Willys started right up, and the ammeter acted like it used to.  That is, it would go to positive at start up and would fairly quickly drop back to 0.

The Willys sat for about 2 weeks without a drive.  When I finally did drive it, the trip was pretty short.  The ammeter stayed in the positive for the entire drive.  The generator just didn't have enough time to fully charge the battery.

I guess my real problem is, I don't know enough about what the ammeter is telling me.

If anyone out there has a firm understanding of what the ammeter tells us...both good and bad, it would be helpful for me, and perhaps others at the 3A.

Thanks,

Tim  

[Bob W]

An ammeter shows how much current is going into (+), or out of (-), the battery. Normally a large amount of power is used up when the vehicle is started, so once it's running the generator will begin to replace that power to the battery. The ammeter will defect toward the (+) side and then gradually taper off to the middle as the battery is charged back up. When the battery is charged, and everything is good, driving down the road, the meter will read in the middle. The generator is supplying the power for everything and the battery is just waiting for something to do. If the ammeter reads (-) the battery is supplying power to the vehicle instead of the generator. This can normally occur at times while idling since generators don't put out a lot of current at idle. If the ammeter reads (-) while driving there is most likely a problem with the charging system. If the ammeter reads (+) continuously, and never tapers back to the center, the charging system is probably overcharging the battery for some reason.

It is easier to use a volt meter to determine at a glance if there is an electrical problem.

[athawk11]

Thank you Bob.  

I had my suspicions about the ammeter function, but was never confident enough to speak out about it.  It just started reading 'different' than I was used to.  I was only smart enough to realize I should ask the question.

Thanks again.

Tim