jedijeb

I have an 85 2.5L and if I don't start it up about every four days the battery will be low enough that it will show 8 volts and not turn the engine over fast enough to start it. Normally it goes a little longer in the summer than in the winter before it gets too weak.

I have measured the draw with everything turned off and it is between 70 and 100mA which is right at the upper range or a little over what is considered normal draw(I figure the older clock will draw more power than most of the newer models).

Friday I went to leave for work and with it being cold it takes a couple tries to start it. Normal older carbed engine problem, start it and it will run a second then die, pump a couple more time, start again, sometimes three tries and it will finally smooth out and run. Friday though it took four tries and on the fourth the volts were down to about 8 volts and it just wouldn't start so I just drove the truck. Today I put a 6 amp batter charger on it, and after about 90 minutes it was at 13 volts and started easily.

With it charging up so quickly, does this sound more like a battery nearing the end of its useful life or some other type of draw that just started to bring it down overnight(it started fine the day before)?

KenR

Battery sounds like it has given it's all and has little left to give. Load test it with a carbon pile tester, not an electronic tester, when it's fully charged. I bet it has very little reserve life left.

Ken R

Bugout4x4

Yep...and this is the time of year they let you know. First cold night and they start to drag. Just had to put two new ones in my Dodge with a Cummins. Only two years old and never missed a lick and even deep cycled great on accessory. Even fully charged the first cold night and they were both gone at the same time. It really is the first place to go to.

67 GMC

Do all your interior lights come on when the door is opened? The courtesy lights on the visor mirror etc? It sounds more like something like a light bulb left on. The lighter socket turns off when the Jeep is off so shouldn't need to worry about having something plugged in to there. Any trailer harness messed up?

jedijeb

Luckily there is no visor light or much of any other accessories. The dome and floor lights go off when the door closes and the lighter does go dead when the key is off. I have noticed there is a relay next to the battery that will click any time the battery cable is removed and reinstalled, and it will also click when I attach jumper cables or the charger once it has gone mostly flat. But so far the clock has not reset, so it doesn't go completely flat, but if it sits for a week it will be down to 8 volts max when you first turn on the key. Once started it will show 14v and if you have to jump it you can drive it 10 miles and it will restart no problem. Also there is no bulb in the under hood light.

This one uses a 58 size battery, if I replaced with an Optima, which size would best fit, doesn't seem they make one that size? I put a Deca in the F150 last year when it died so I may get another one of those. The one in it is an Advanced Auto silver I think.

craigjacob1

I had a similar problem. I replaced the battery with an optima yellow top which temporarily fixed the problem. I later found out that the actual problem was a corroded battery+ to PDC wire.

67 GMC

It still sounds like a parasitic drain to me. I have a Jeep and a VW that sit for days to weeks without driving and start right up every time. Neither have new batteries. If you think it's the clock, pull the fuse and see if it still goes dead. Also, pull radio fuse. With all that load disconnected, there's nothing that should still be powered up. I'm not sure on an '85 if there's an ECU (could be some power to that with key off).

jedijeb

The 85 does have some sort of computer under the dash, the only thing it does is retard the spark when cold, which I had to bypass because it wouldn't let the spark fire, and turns on the power to the electric choke once the oil pressure is high enough. I believe I could totally disconnect the computer and never notice it since I have the choke removed and the distributor wired directly to the ignition module. I believe an actual ECU was added in 87 when the Renix Jeeps came out.

I have measured the draw at about 100mA, which is about 30mA more than normal, but that still should take weeks or months to draw down a good battery I would think.

craigjacob1

I totally missed that you said it was an 85.

You could go through your fuse panel, and make sure that the fuses are correctly rated.
Sometimes people will put larger fuses in a spot because one keeps blowing. If you have the correctly rated fuse installed in all locations and one blows it could help you locate a shorted wire or connector.

jedijeb

Ok finally back home and picked up a new battery. Starts first turn of the key now

I started pulling fuses and measuring draw, no draw on the radio fuse which is also the lighter fuse and none on the one labeled clock. I did get 77mA on a 10A fuse labeled ETR Radio/Power Antenna. I don't have a power antenna so does anyone have an idea of what that might be?

It is #12 on this diagram http://www.carfusebox.com/jeep-chero...eaker-diagram/

With it out the clock doesn't show up so it seems it is related to that somehow.