Good Battery Keeps Dying

[strokeZ]

Hi all,

So after my little situation with the front drive shaft the battery keeps losing charge. I charged it after I picked it up from the dealer and then drove it for a few days with no problems. I let it sit for a couple of days and drove it again - no problems. I just got back in town and the Jeep sat for about a week - battery is dead as a door nail. I am thinking a slow drain somewhere - but before I parked it I made sure to disconnect all the extra stuff that I have hooked up (CB, Lights, sub amp, etc). Still - it died. I did some research and wonder if it could be the little yellow wire under the hood or the Starter - Battery - PDC harness - question is if these will slowly kill the battery over time??

The battery has been tested a few times over a few methods and appears good.

Thanks for the help.

[Matt]

I'm not sure if our service manual has it in it... i'll have to look because it should... but you should be able to measure the draw on the battery with all systems off to determine if it's higher than normal. It there's too much current being pulled, next step would be to figure out which circuit is causing it then go from there.

[strokeZ]

If you can find that it would be cool. I know there is a small draw just to keep the systems alive but not sure what that is. I have it under trickle charge right now and will test when it's able to start.

[Sal-XK]

Just a thought if you leave the battery disconnected and see if it holds a charge you can narrow it down maybe unless the battery has a internal short that occurs only when connected which happen to my mustang took me 3 months to figure that one out.

[strokeZ]

Good point Sal - will try that as well and thank to both of you!

[cico7]

How old is the battery? If the battery is 5yr 50k miles, it needs to be replaced.
Can you get a hydrometer to test the acid?

[07JeepXK]

I know this is a long shot but are you sure the alternator is charging the battery properly. If you have a small drain on the battery and the alternator isnt working properly then there is no way to keep the battery charged.

[strokeZ]

The battery is about a year old and about 10k miles. I had it tested at a few different places and it has always come back okay. The alternator was charging good per dealer and the battery shop. I know there are issues with the battery testers so I have had it checked at three places. All came back as OK. The things starts just fine if I let it sit for a day or two, but seems like if it sits past four days or so it dies.

UPDATE: Just checked the battery with a multi meter - with the car running it reads between 14.38 and 14.45V. With the car off it reads ~12.6V. Also with the car off I am showing a draw of 0.15 mA - not sure if that is spec or not?? I wonder if I cracked my battery during the last "baja run" over the trails at Big Bend - I suppose that is possible as well. Hmmmmm

[Sal-XK]

That's more then possible and like I said earlier very hard to diagnose. I swore my mustang bat was good and it ended up being an internal thing what threw me off too was the battery was only about 1 year old.

[Matt]

You mean 15mA, right? That sounds about normal.

If a module or something was draining the batter after a few days I'd expect to see a 500 or more mA draw.