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Alternator and battery draining.

el_roy1985

NAXJA Forum User
Location
Bismarck, ND
For a while I've been having problems off and on with my Jeep just losing all it's charge. Although now not only does that happen all the time, my alternator is overcharging. Could the drain be caused by the alternator? I'm really hoping so because I've been trying to figure it out for a long time. Right now the alternator will charge anywhere from 13v at idle to 16+ when the RPMs go up.

Then tonight on it's last voyage till it gets fixed, my Headlights went out but the high beams work. I'm hoping that's just a fuse.

This Jeep seems to be nothing but problems for me. Hopefully this problem will be easy to fix. Cause I don't know how much more I can take from the damn thing.

I have a 1987 XJ with the 4.0.
 
Sounds like the alt is working OK, Have you tested the battery for shorted or dead cell.

Could be your positive battery cables shorting out intermittantly.

As for the low beam lights, does the high beam go off when you use the dimmer and come back on with the second click?

if so, the dimmer switch is probably OK.
Try pulling the socket off the rear of the sealbeams.

See if there's any corrosion on the contacts, slide them on and off a couple or 3 times.

Somtimes that will bring the low beams back. I don't think there is a seperate fuse for low beams.

Autozone will check your battery for FREE.
Good Luck!
 
an alternator running 16 plus is NOT okay. an alternator should rarely run over 14 volts and then just barely. 2 plus is a lot of extra voltage. i saw this problem in a sidekick (same with headlights and all). the voltage regulator in the alternator is fucked. replace the alternator ASAP (don't run it at all) and hope to god that half of the wiring isn't totally fucked. the battery might still hold a charge, but i doubt it. hope that helps.
 
JoesXJ said:
I'm not 100% sure but I believe the regulator is in the PCM

He said he's got a 1987. That means a Delco alternator with an internal regulator (I should know - I've got five...)

It's possible the regulator is shorting through, which causes the output voltage to increase - this results in overcharging and overheating of the battery. If this has been going on for some time, he's probably looking at getting both the alternator and the battery replaced soon.

Nominal alternator output voltage runs +13.5-14.5VDC, with anything over 14.5VDC being bad for the battery.

Suggestions -
First, check the alternator output voltage with a DMM - the voltmeter in the gage panel is a notorious liar.
Second, get a hydrometer to check your battery (if you still have a conventional battery, and not an AGM or a gel cell.) Check the specific gravity (in this case, acid concentration) of each cell with the hydrometer - if any one cell varies by more than .020 sp. gr. from the rest, you've got a dead cell. It's possible to have more than one dead cell (most I've seen is three,) but a dead cell will cause your battery to self-discharge overnight as the other cells try to charge the failed one (and that don't work.)
But, and most important, take the dashboard voltmeter with a significant grain of salt - the damn thing is usually wrong. I tend to mark mine where a "confirmed" nominal reading happens, and just use it more for relative state-of-charge than an absolute voltage reading.

For the headlamps, checking the dimmer switch is a good idea, and the procedure given to you is spot on. I can't swear to it at the moment, but I believe the high and low beams are on separate fuses - you should be able to get your wiring diagrams (you can use 1987 or 1988) from my RENIXPower group - groups.yahoo.com/group/RENIXPower.
 
Don't want to hi-jack the thread...but I've got an issue with lights "flickering"...especially at idle. dash lights flicker...so do head lights. Alternater is relatively new...less than a year since the orignial died (NAPA replacement). Any ideas?
 
Flyfisher said:
Don't want to hi-jack the thread...but I've got an issue with lights "flickering"...especially at idle. dash lights flicker...so do head lights. Alternater is relatively new...less than a year since the orignial died (NAPA replacement). Any ideas?

Shonky ground, most probably. Check the ground strap from the cylinder head to the firewall - it's the main ground for the chassis (which grounds through the engine block.) Clean the spot under the screw head on the firewall down to bare metal (about the size of a postage stamp,) apply corrosion inhibitor, and reassemble.

Also check the open braid of the ground strap itself - it may have been collecting crud for the last few years, and is a shonky ground to begin with (in which case, cleaning the firewall won't help much. But it should be done anyhow.)

Replacing mains is also an option - I've gotten good reports from the field on doing that...
 
I already did a little bit of research, so I knew the alternator was internally regulated. (thank goodness) I was just getting more opinions on the problem. So thanks for everyones help. The wires look good as far as what I've seen. Yesterday I was driving to work and the voltage skyrocketed for a fraction of a second then my Jeep died and would backfire very loudly while I was still coasting. Then it started back up and I made it the rest of the way to work. So after work I drove home and it will sit till it's fixed. So I guess I'll be getting a new alt. from motor city reman since this one is lifetime warranty. Been a really good alternator up until recently.
 
This may sound silly but someone told me or I read somewhere that wet carpeting could be the culprit for draining the battery....and their theory was that the harness for the power windows and locks run on the floor under the carpet. With it being soaked, current is leaching thru the insulation and causing a draw. Don't know if it's possible and take it for what it's worth. My '89 with wet carpets and power windows had a mystery "draw" and seemed to disappear after I went carpetless. Again, maybe a coincidence but
................?
Ron
 
A bad alternator diode can cause overcharging. Might be worthwhile to test the diodes, or have the alternator itself tested.

But you might also see an overcharge if the battery is really bad and not accepting charging current. If your battery is flat and you're starting with a boost every time, that's a good possibility.

As for the apparent drawdown, once you have a known good battery and a known good alternator, one option is to turn off everything, and use an ammeter between one battery terminal and the corresponding cable. Take a reading. If it's more than the few milliamps needed by the clock and the radio memory, start pulling fuses, one by one. If you're lucky, one will stop the drain, and you'll at least be closer to finding the problem. Since interior lights are on the same circuit as the clock and radio memory (at least in an 87 XJ), that's a good one to pull first. With that one out, there should be no other current pulled when the car is shut down, unless there is some alarm system/keyless entry etc. too.
 
I had the low beams go out on my 89 while the high beams still worked. It was because a connector right below the ballast resister had partially melted. I had to cut it out and splice all the wires. You can see a picture of the connector here.
http://pictures.aol.com/galleries/bjlinma/a240HCxOt2sh8Td5v2vJM7UHkCJqHlvC9**qv4xQp5Fd3Ig=

The corner wire that's melted the most was the low beam feed to both headlights. Fixing all these connections brightened all my front lights. I also added a braided wire from the negative on the battery to a bolt on the front sheet metal right infront of the battery.


I've had several electrical issues with my 89. Most recently, the battery was going dead over night. It turned out to be the power antenia. It's relay is powered even when the ignition is off. Pulling the fuse fixed it. I pulled it with the antenia UP. :)

Any of the circuits that stay live after the ignition switch is turned off could be the cause. As pointed out above, one other is the power window/power lock/power seat circuit. Another is the dome light circuit.

What I did to find the last one was hook up the charger when the battery was dead and watch the meter on it while I pulled fuses out one at a time.

The load on the charger dropped alot when I pulled the Antenia fuse.

If your Charger has a load meter, give it a try. It works best when the battery is dead. You'll get the biggest swing then.
 
I had a similar incident in a 73 Chrysler many years ago, The alt blew a diode while night

driving. It acted like all of a sudden the alt was putting out 120 volts AC. The headlights

flared up as bright as strobe lights and it blew every light bulb and headlights that were on.

Autozone will check the alt in the vehicle or off the vehicle. Hope you get your's figured out, good luck.
 
I'm with Matthew Currie, have the battery load tested. If you have a dead or shorted cell, the alternator is going to try and compensate. A good tip off is after the battery has sit all night, do a volt test. If a cell is bad, it will often show only 10 volts or so. Sometimes when it is realy cold it may show 11-11.5 volts, so this isn't a diffinitive test. The alternator is supposed to have a 16 volt max output, so it's possible it is OK and the problem is something else. I've had a cell in the battery break loose from bouncing around and short inside the battery. I could actually see it sitting crooked through the filler hole.
If your alternator has been overcharging, there is a good chance that the battery has spewed some, the battery electrolite on the outside of your battery is a good conductor, even the fumes and the salts left on the outside of the battery conduct well. You can loose juice,through the electrolite on the outside of your battery to ground. I've had batteries overheat and vent and you could actually hear the crackle as the juice found it's way to ground through the elctrolite and/or the acid salts from the fumes. Wash off the battery and the tray, hot soapy water works about as well as anything else. A high pressure washer will also get it done, but be a little carefull of the eelctrical componenets and connectors around the battery.
Like mentioned the cable splices under the carpet on the drivers side are a likely place for corrosion and line leaks, though there are other spots.
Another possible trouble spot is coolant inside the alternator, coolant is also a good conductor, if your cooling system has spewed recently and the alternator has coolant in it, this can cause all sorts of grief. As can coolant soaked connectors.
 
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Coolant has spewed out of it recently. Had it overheat on me since the idler pulley went out. I've also pulled my fuses for the interior lights and the remote starter, they didn't stop the drain. I had the Battery tested a few times to make sure it was still good. I also had the charging system checked the day it was giving me trouble. It showed that it was charging at too high of a voltage. I'll probably take the alternator out in a day or two and take it to checker and have them test it. There is no autozone where I live. Although O'Reillys lends out tools now, so I guess I'll be fine without an autozone now.
 
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