Need help with a battery issue in my 04 LJ.

[TFRI]

I started having issues a few weeks ago with my jeep starting in the morning. all of the gauges come up. the clock and trip odo reset. with a few pushes on the gas I can normally get it to start. I have been using my Battery Tender JR over night and it will run great that day. the next morning same problem as before. I'm not sure if it is the battery, the alternator or the PCM. I'm running Optima Yellow Top (It was in the Jeep when I bought it, so I don't know how old) and stock alternator.

I have read a few articles about the stock alternator not having optimal output to keep a deep cycle battery in the best condition. I also read that the PCM for this year (it has a power regulator for charging the battery on the board) can malfunction and cause charging issues.

I am not sure where to start troubleshooting and all replacements are a little spendy... Any help would be great!

Thanks! -T

[Black_ZJ]

I have the yellow top in both of my Jeeps with higher output alternators and couldn't be happier, so you could indeed be having issues with the battery not fully charging. This is why so many people think their Optima is dead prematurely when in fact they are simply under charging them. And that battery tender may actually be doing more harm than good.

[TFRI]

Is there a recommended amp output for the alternator? What kind of charger should I be using to get this thing back into shape?

[irish1371]

i would check/flex all your grounds and battery cables for corrosion hidden under the plastic. Also check your wiring to the alternator

You can go to any auto zone and get your alt and battery checked for free to see if they are the issue also

[bob91yj]

I've never had an issue with the alternator on my LJ keeping an Optima yellow top charged, factory alternator is approx 115amps if memory serves. I'd suspect a faulty battery. Most Auto Zones will do an electrical test at no charge.

[1stDeuce]

Do you have a volt meter? If not, get one! You need to check voltage at the battery with the engine running, and after at least a 5 minute drive. You should see about 13.8 volts with most everything electrical turned off. Then turn on the headlights, turn the heater to high, and if you have it, turn on the rear defroster. go check voltage again. It should still be above 13 volts and preferably nearer 13.8 still. If you've got less than 13 volts with the engine running and the car's accessories on, I would suspect either the alternator is getting weak, or the PCM is charging to a low voltage, which will kill the battery. If voltage looks good for both of those tests, then suspect that the battery is on it's last legs. This would be somewhat supported by the fact that it's starting better when you charge it overnight... It would have a higher surface charge, which would start the engine faster. If that is the case, it should also start good right after you shut it off after some driving. Have the battery tested at the auto parts store, don't replace it with another optima, or use a red top if you do. (I have better luck with the red tops, but the best batteries I've had said Everstart on them.)

Gel cell batteries (Like optimas) do have different charging requirements than flooded lead-acid batteries, but normally, you're not discharging them much, so they are reasonably happy in most auto applications. Jeep actually charges at a slightly lower voltage than many auto makers, so they're one of the better platforms to put gel batteries into IMO.
Good luck.
C

[TFRI]

i would check/flex all your grounds and battery cables for corrosion hidden under the plastic. Also check your wiring to the alternator

You can go to any auto zone and get your alt and battery checked for free to see if they are the issue also

I have checked for corrosion. I will look at the wiring to the alternator and go have it tested when I get home. Thx! T

[TFRI]

Do you have a volt meter? If not, get one! You need to check voltage at the battery with the engine running, and after at least a 5 minute drive. You should see about 13.8 volts with most everything electrical turned off. Then turn on the headlights, turn the heater to high, and if you have it, turn on the rear defroster. go check voltage again. It should still be above 13 volts and preferably nearer 13.8 still. If you've got less than 13 volts with the engine running and the car's accessories on, I would suspect either the alternator is getting weak, or the PCM is charging to a low voltage, which will kill the battery. If voltage looks good for both of those tests, then suspect that the battery is on it's last legs. This would be somewhat supported by the fact that it's starting better when you charge it overnight... It would have a higher surface charge, which would start the engine faster. If that is the case, it should also start good right after you shut it off after some driving. Have the battery tested at the auto parts store, don't replace it with another optima, or use a red top if you do. (I have better luck with the red tops, but the best batteries I've had said Everstart on them.)

Gel cell batteries (Like optimas) do have different charging requirements than flooded lead-acid batteries, but normally, you're not discharging them much, so they are reasonably happy in most auto applications. Jeep actually charges at a slightly lower voltage than many auto makers, so they're one of the better platforms to put gel batteries into IMO.
Good luck.
C

I do have a volt meter. I will try this out before heading to Autozone to get things tested.

I'll report back later...

Thanks you everyone! This community rocks!

[TFRI]

So it looks like the alternator is good. it's running at 13.6 to 13.8 volts after starting. after a 5+ min drive it was running at 13.8 volts. A quick drive over to AutoZone and they are telling me it's at 86% and won't take a charge. so now ordering a new battery.

T

[bob91yj]

Lesson learned, start with the simple stuff! There is a catchier phrase that applies in my case, K.I.S.S. (keep it simple, stupid).

I had a driveline vibration in my YJ years ago...let's see if I can remember...

Decided it was the tcase, pulled it, overhauled it (chain was slightly stretched), put it back together, not fixed.

Decided it was in the transmission, pulled the tcase/trans, swapped in a spare transmission I had that had the external slave cylinder, put it back together, not fixed.

Decided it must be my driveline angles, installed a Daystar 1" body lift, and 1" engine mounts, STILL not fixed.

Finally decided to put it on jackstands and run it, removed the rear driveshaft for the THIRD time so I could run just the front end, noticed the CV joint was floppy/loose, took it to my driveline guy, he rebuilt the CV, put it back together...FIXED!

On the plus side, I got a lot of stuff done my Jeep that had been on the back burner for a while!