Battery Draining

All of a sudden my battery is draining over a week if the XJ is not driven. I bought a new battery and that hasn't helped. This is a new condition, it used to hold a charge forever. Does a 95 XJ have any history of something like this?

Make sure the battery itself is clean. Excessive dirt can cause a drain. If you have a voltmeter that has a amps function you can see what kind of drain its pulling while its off by pulling the negative cable and putting your meter in series.

Thanks, the battery is new so it is clean. I think my volt meter has amps. I am a good mechanic but terrible at electronics.

My meter has a place with an upside down horse shoe kind of thing. Settings are 200K, 20K, 2K, and 200. Is this amps, if so where should I set the switch?

It also has a DCA place

I'm sitting here thinking about this and guessing DCA is DC Amps and the horse shoe thing is ohms. So I'm trying to figure out where to set the switch, 200u, 2m, 20m, 200m
Any help?

I'm having the same problem with my '97. I'll charge it and then it will be dead the next day. It has been hell to research online as opinions are many but solutions are few.

Here is what I've learned... if the alternator has a bad diode, it will drain the battery and the longer you let it go, the quicker it will drain the battery.

So, I charged it up (for the umteenth time) and my son drove it down the driveway where it just died. Nothing. I pulled my truck next to it and jumped it and it started back up only to die again as it was pulling up to the house. I have an Optima red-top in it and after fully charging it, I was able to drive the XJ onto my trailer and haul it to AutoZone in town. The counter monkey said the battery was fully charged and ok, but the damn thing wouldn't turn over. It would click once and then silence. Nada. I'm going to replace the alternator as that seems to be the next logical step. To recap, the XJ has power to everything (interior lights, radio, etc.). It will start with the battery fresh off the charger but won't drive a 5th of a mile before cutting out. If the battery was bad, it shouldn't hold a charge. I'd say battery first, but I pulled a new battery (that came in the xj when I bought it) out after experienceing the same crap and replaced it with the Optima from my TJ. Also, what you describe seems like the same bs. All relays and fuses are good and it seems like there is a constant drain on the battery, so I am thinking (hoping) it is the alternator. Seems like there are several threads on the various forums that indicate the Cherokee, by design, had a weak alternator.

Hope this helps!

BTW, run it by AutoZone or Checker. They'll check your battery and alternator for free in the parking lot.

Thanks, that is helpful info.

I will also check (and clean up) the crank positin sensor (CPS or CKS) and this post seems helpful...

Never use the ohm (upside down horseshoe thingy) settings with a live circuit--it will blow the meter.

It sounds as if you have a constant drain. Modern radios with "presets" are a small drain, but not enough to kill a battery in a week.

You can hook a voltmeter or 12v test light in series with the battery cable and the battery. I prefer the test light as I can see it while I am pulling fuses to determine which circuit is causing the drain. Again, if you use a test light there should be a very slight glow from something like the radio memory, but a bright light indicates a heavy draw. Just pull fuses until the light goes out and then trouble shoot that circuit.

tgregg said:

My meter has a place with an upside down horse shoe kind of thing. Settings are 200K, 20K, 2K, and 200. Is this amps, if so where should I set the switch?

Click to expand...

That symbol stands for Ohms.

Usually meters will have a separate place to plug in the positive lead for amps and they will have a dial setting for amps, set it to the highest setting available to start with.

One thing you can check with your voltmeter is whether your alternator cables are giving you excessive resistance. You can do it by putting the positive lead, with it set to volts, on the output post of the alternator and the other lead on the positive battery cable. If you got a bad connection you will see maybe 2 or 3 volts showing on the meter or dropped. It would probably be a good idea to make sure all connections are clean anyway.

Until you figure it out, you can try identifying if it is a component that is supposed to retain information or if it is something that is normally draining.

In the under hood fuse/relay compartment, there is a fuse labeled I0D ignition off drain.
if you pull that fuse and let it sit, if it drains then you have a shorted wire, or bad component.

joe_peters said:

Never use the ohm (upside down horseshoe thingy) settings with a live circuit--it will blow the meter.

It sounds as if you have a constant drain. Modern radios with "presets" are a small drain, but not enough to kill a battery in a week.

You can hook a voltmeter or 12v test light in series with the battery cable and the battery. I prefer the test light as I can see it while I am pulling fuses to determine which circuit is causing the drain. Again, if you use a test light there should be a very slight glow from something like the radio memory, but a bright light indicates a heavy draw. Just pull fuses until the light goes out and then trouble shoot that circuit.

Click to expand...

Yes the radio is a draw but the same radio has always been in there and it never was a big draw. Something big is pulling it down. I'll try the test light trick and take a check on the IOD ignition off.
Is the alternator diode something I can or should check?
Thanks

Nice article on diode testing at the bottom of this page:

http://www.noahtec.com/testing-diode.htm

My XJ has 218K on the odo and the alternator looks original. I'm thinking if the diode thing is a viable possibility I maybe should just replace it anyway. What do you think?

Have you put a voltmeter across the battery while running to see if you are getting between 13 and 16 volts out of the alternator. Thats a good way to see if your alternator is working ok. Also check the cables before you replace.

Thanks I try that. The battery is draining though rather than not charging. I think it is charging but I'll make sure. The post indicating that the diode could be discharging the battery has me thinking I should change out the alternator.

We have to get to the orignal problem which is determining how many amps an XJ should draw in it's "at rest" state. Time to search.