Charging Issue

I am currently having issues with my alternator charging my jeeps battery....I think.

I say "I think" because I can not tell if my alternator is actually recharging my battery or not. Last January I replaced all the wiring, the battery, alternator, volt regulator and started solenoid, so those items are essentially new with under 1,000 miles on them. Also with the old parts and new parts my jeep barely showed over 12 volts on my volt meter on the dash.

Here is my current delema. About a month ago I did some work on my heater unit and finally got the blower motor hooked up and working. After driving the jeep around for a full week with no issues I go to start it one morning and nothing, nada, dead. When I say dead I mean it was really dead, wouldn't even make a sound when the key was turned. So I go to jump the jeep and I get it running. I leave the jeep running a for about 20 min to ensure a decent charge. However when I shut the jeep off, then go to start it to see if the the battery charged, it refused to start. The battery was still completely dead.

So I get the jeep running again with a jump start and check to see if the alternator is putting out power, turns out it is. So after turning the jeep off I take the battery out, the alternator out and the volt regulator. I have the alternator and battery checked at Napa to see if they are still good. The battery tested positive and the alternator put out 14 volts.

I put the parts back in and the jeep fired right up, however I am very weary at this point. When starting the jeep the volt meter reads 10 volts with the headlights on. When I turn the heater on it drops below 10 volts with the headlights on as well. Only once I have started driving does the volt meter jump to 12 volts. However most of the time it never jumps up to 12 volts and stays well below that.

What is the problem? I feel like my alternator is only working part of the time and when it does it barely puts out enough power.

 

I suspect three things.......Alternator Belt Tension....... Belt Condition.....Belt Engagement.

If belt is too loose..... no charge...... if you can rotate fan b y hand, without engine running, belt is too loose OR it is engage incorrectly......make sure the belt is NOT bottoming out on pulley......the belt works on the SIDES... not the bottom.

Condition....... if the belt is glazed... it can also slip. Belt dressing can TEMPORARILY improve this.......so can a NEW belt if the tension or bottoming out are the culprit.

 

Hmm interesting suggestion. The belt was new with everything else I installed. Ill go try screwing around with the tension tonight.

 

I assume you are still running the original style alternator with the external regulator?

Do you have a hand held multi meter to confirm the voltage at the battery posts while the engine is running?

You should read 14.5-14.9V without lights and blower on, and 13.0+ with.

 

I am running an original style alternator with an external regulator.

I checked the volts being put out with the multi meter and a spare volt guage I had laying around and at the battery its only putting out 12 volts.

What should I do now?

 

Certainly the first thing to do is take the battery to your FLAPS or where you bought it and have it load tested. The battery or something simple like corroded connections is the most common problem. You should also check that the batter is not being drained by the car while it sits. You can use the amp connection of your multimeter for this (everything off, look at the current flowing from a cable back to the battery).

That's the voltage across the battery with the engine running? It should be about 13-16 V. The charging voltage is somewhat above the 'nominal' lead-acid battery voltage of 12.6 V.

These alternators are known for popping diodes. You can lose one of the output diodes and that will drop the output voltage of the alternator some. The alternator will function but will be weak at charging the battery. The right way to test is to put a scope on the alternator output and look at the shape of the waveform. Loss of a diode will show up as a gap in the output.

Back in the day, the mechanics would repair the alternator with a new diode. Today, separate parts aren't usually available except to rebuilders. The easiest repair is to swap out the alternator.

 

So your problem started after you re-worked your heater motor/switch system, correct?

A slow battery drain will sometimes let you run ok for about a week before a no start condition appears.

Easy drain test= Remove one of the battery cables (either one) and connect your test light between the battery and the cable.
If the test light comes "ON" then you have a drain. Remove one fuse at a time until test light goes out and you have found the gremlin.

I usually leave the fuse out and go to the next one just in case I have two gremlins.

 

I had the same issue and went through my whole charging system... found that the issue had to do with the alternator light on the speedo. The bulb did not work and was shorted. Repaired it and charging system worked fine after that. Never knew a bulb in the dash would cause it not to charge.

 

FIXED!!!

After going through the whole freaking jeep I found the problem. In fact I am still dumbfounded that it turned out to be such a simple fix. Turns out the prongs on the ignition were corroded which prevented current from traveling to the battery to recharge the system.

Kinda mad it took me a month and a half to figure this out!

 

Glad you found it. Yep it can be a PITA for sure. That is why I don't like those plug in ign switches.