Use an ohm/amp meter to measure the draw on your battery with the key in the off position with the stereo disconnected. If it is negligible you can rule out the wiring. Then you just have to figure if the problem is battery or alternator related. Good luck if it is the electrical harness. It took me a few tries to find the ground that was draining my battery was in my ignition harness inside the steering column.
A loose or polished up fan belt can cause those symptoms, same as a dirty end on one of the battery cables. (Don't forget cables have 2 ends.)
I test the belt by taking a cold off engine and seeing if I can hand slip the pulley. If I can, it will slip under load and cause your symptoms. If the belt is tight and still slips, then it can be polished up. I used to polish up 2 or 3 a season when I played in the mud pits. Mud=liquid sandpaper.
86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
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An anyone help me diagnose my cj? Not every morning, but frequently jeep has a dead battery. I've ruled out the charging system. It is working fine. 13.75 volts at idle.
Battery is about 3 y/o. It takes a charge, at least initially. I'm not sure how to test if the battery is bad and losing its charge, or if I have a parasitic draw taking juice from a good battery.
One more tidbit. The battery can go dead with no warning. It did this while sitting 15 min at Walmart.
1973 CJ 5, 232, T-18
If it croaked in 15 minutes, then it's not the battery unless you have a broken bridge between cells in the battery.
This is common with the 'Six Pack' or 'AGM' batteries...
Works once, then 5 minutes later (When the bridges between cylinders have vibrated apart) the thing won't start,
Then it will start again the next 5 times, then won't start again...
Batteries have fairly large bridges connecting the cells together to make your 12+ volts, but more importantly,
Connecting cells makes AMPERAGE, which turns the starter.
When bridges crack, they CAN conduct Voltage, but will not conduct AMPERAGE, which is the cranking power needed for things like the starter.
You will ONLY find this issue with a full on load tester when the thing won't start...
This could be an issue with battery to cable connections.
When you 'Jump Start', you connect to the OUTSIDE of the battery connector terminals, and you CAN have an issue with the INSIDE of the connection, between terminal and battery post.
If 'Jiggling' the connectors works to start the engine, then you have a connection problem,
Time for reasonable terminals or new cables entirely.
Knowing what you do to get it started again would help diagnose the issue.
If you tinker with cables, tap on the starter relay, ect.
What noises does it make when it won't start? Do you hear the starter relay 'Hitting' but the starter not turning?
Or doesn't the starter relay 'Hit' at all?
You describe what's happening exactly. Works fine, no slow starting or dim lights to show a low battery and then poof. No juice at all everything's dead. Checked all the cables and connections and they're good. Originally thought it was a charging problem and I found some loose connections on the alternator. I replaced them, but it didn't fix the problem.
I disconnected the battery last night to see if it would go dead out of the CJ. When I connected my charger to the battery my charger said the battery is no good. That was a first. I've charged it several times and not gotten that message before.
After work today, I bought a new battery. We'll see if that solves the problem. I'll let you all know. Cross your fingers.
I know this is a bit off topic but I've replaced a few batteries in 30 years of ownership and never really found a battery that fit just right. Sometimes it seems that because of the cable position the battery has to be put in facing backwards. No big deal but the label is hidden and the terminals are near the back (firewall). The last time I needed a battery I went to Advance Auto and sure enough the proper battery listed for the CJ had the terminals reversed. It would have to be installed "backwards". They had a great (online only) sale with 25% off for a 36 month free replacement battery which was $80 instead of the usual $110. I picked out a battery at the store based on length, width, height, terminal position, etc. and discovered the perfect battery was a Group 24F. Again, the sale price was online only (but with "in store" pick up). Advance Auto online requires you to specify a vehicle though before you can order. It turns out that a Group 24F fits a '98 Toyota Camry. I added the Camry to my "garage", found the battery for it, paid with my credit card, went to the store and picked up the battery and saved 30 bucks. The funny thing was that the day before I was convinced my battery was fine but my starter was shot. I looked at my records and found that I had bought the starter 22 years earlier in 1992 from Discount Auto (Advance Auto's prior name) and it had a "lifetime warranty". I still had the receipt. They gave me a new starter for free and told me to keep the old receipt in case it ever failed again. It turned out to be the battery.