Battery drain?

1960 cj5 f134. After 3 days my battery is dead. I charge it up and repeat the cycle. I replaced the battery 2 weeks ago thinking my 1st new battery was defective. How do I determine if something is draining the battery and where it is? Btw, I have a new wiring harness. Thanks for any suggestions.

 

Put a 12v test light between the negative battery terminal of the battery and the negative cable clamp (positive side connected, negative side disconnected). If the light lights, you have a draw. A dmm (digital multi meter) set on dc volts is much more accurate but if the draw is enough the light will light if that's all you have. If you have a draw, remove fuses or disconnects circuits one at a time until the light goes out on the test light or the dmm reads extremely low reading (0 is preferred).

 

I would do some simple and free tests first.

Do you own a multimeter? If so, use the amps scale and measure the current drain in series between the battery positive cable and the battery positive post. This should indicate none or at most a few milliamps of drain. If you read some large number of milliamps, something in the wiring is draining the battery.

If not, charge the battery fully and leave it in the Jeep with the cables disconnected for 3 days. Then connect the cables and see if it starts. If the battery is flat, it's clearly a problem with the battery. You can also take the battery to your FLAPS and have it load tested.

You can guess at what kind of current is needed to drain the battery in 3 days. If you have a battery with, say 100 AH (amp-hours) should power a 1 amp load for 100 hours, or a 100 amp load for 1 hour. So a 700 milliamp load will half-drain a 100 AH battery in 3 days ... (100/2) / (24*3) = 0.694 ~ 700 milliamps. So if you find a 10 milliamp drain, that's unlikely to be enough to drain your battery... at least not over 3 days.

If there is a problem in the wiring, start disconnecting things until the drain goes away.

 

What I do is remove the negative battery cable and hook an amp meter between the cable and post. If you have a current draw with the ignition and all accessorys off, something is still using current or you have a short. Then you need to start disconnecting items (or pulling fuses if you have a fuse block) until the current draw stops. That will more or less isolate the problem. Have to ask if this has an alternator and if so, is everything but the battery lead wired through the ignition switch? With an aftermarket harness, there are probably a lot of opportunities where something could be wired to power even with everything turned off.

 

To offer a slightly different solution... Do unhook your battery to test it then place a manual disconnect on your positive terminal post. My use is NOT daily during the very cold weather. I do not have a fuse box. I did rewire it without a kit. I never found the power drain.

 

I placed my test light as suggested and it lit right up. I will install a cut off until I can find the problem. I can start disconnecting some of the circuits, but could I get some suggestions of what exactly I am looking for. I'm really new to this and appreciate the help. Thanks

 

You have a new wiring harness? Who's harness? Is it a hot rod harness or a OEM reproduction? Do you have a wiring diagram?

The first thing I would do is remove all the fuses and see if the leakage goes away. Then start replacing fuses one by one until the leakage comes back. This way you isolate the problem to the part of the harness that is served by that fuse. Then look at the wiring diagram and see what is served by that fuse.

 

Agree. The drain circuit may not even be fused. One example is the alternator.

 

That's where mine was. One of the PO's had converted to a internally regulated alternator & the PO I bought it from had wired up a external regulated model...Just happened to be the last one I checked. I was really surprised it hadn't fried some wires.

 

The alternator that came with my J20 had a constant 20ma drain. A new alternator solved the problem. This was a Delco with an internal regulator, and I don't know if it was the regulator or the diodes in the alternator that were the problem.

A '60 F134 CJ-5 has a generator, unless it's been upgraded. Generators should not leak unless they have a solid-state regulator... then the leak would come from bad components in the regulator.

 

Ditto on the alternator diodes. My 88 YJ has an intermittent drain. It will kill the battery overnight, but only once in a while, so I can't diagnose it. Already replaced the alternator. Making me crazy.

 

Another thing to look for is a conductive dirt track from the positive terminal to any ground.

if you take the ground cable off and then touch it to the negative terminal and get a spark, you may have a wire somewhere that is pinched and will drain the battery because of that. Could also start a fire if you don't find that item that is doing the pinching, because that wire will heat up.

 

If I disconnect everything from the alternator and I touch my test light to the disconnected negative cable and the battery (n), and the light doesn't light.; will I have discovered the drain?
Thanks

 

Probably so. Do you have a tach ? Had one of those mess with me once.

 

Disconnect the heavy wire going to the BAT terminal on the alt "ONLY". Then see if you still have a drain. If no drain, then it is the problem with the alt. Make sure that BAT terminal only has the one wire from the battery.

 

My in line brake switch went bad and would draw contsantly, maybe check that out.

 

Checking where wiring goes through the firewall is a good spot. If no grommet, or the grommet is splitting where it meets the metal of the firewall you could have a short.

 

Problem is, Wiring can be a real pita to trouble shoot. Good luck!

 

Maybe... don't rush out & buy another alternator until your sure what the problem is...
This is just a GUESS... but your problem sounds an awful lot like the one I encountered when I first bought my jeep earlier this year. The PO had installed a cutoff switch (he told me it was theft prevention but I suspect it was because of a battery drain he couldn't solve)...it also had a new alternator on it...

How bout a pic of the back of your alternator & one of the alternator to battery wiring???