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Odd Battery Drain

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Odd Battery Drain
ShotgunFacelift

ShotgunFacelift

Jeeper
Posts
110
Thanks
0
Location
Palm City, FL
Vehicle(s)
1983 CJ7
I've had a battery drain for the last few days. Started with an old battery that finally kicked the bucket. Bought a new battery and got home just fine. The Jeep sat over night and the next morning the battery was completely dead. Tried charging and it just starts draining inmediately (verified by voltmeter). I did some searching and read to disconnect the battery negative cable and hook up the voltmeter between the negative terminal and the negative cable. Then start pulling fuses until it stops draining...

Well, I did that. Except as soon as I pull the negative cable the battery stops drinking and voltage starts going up! There is nothing on that negative circuit except for a ground to the block and a ground to the firewall. Am I missing something here? Any help would sure be appreciated.

Thanks in advance.
 
So with the neg disconnected and a volt meter between - post and - cable you get 0.
 
Shotgun, I'm no electronic guru, but I do know that breaking the negative post loose and inserting a voltmeter is the same as dropping the negative cable and measuring volts across from POS to NEG post. You've broken the circuit and electrons can't glow.

I had a similar drain when my '80 CJ7 came home from the PO. Someone had installed a bar of floods above the windshield, and had made a wiring error that bled the battery out. I scrapped the floods, and the battery discharge went away.

What is needed to measure battery current flow is am ammeter. The ammeter will register how fast your battery is bleeding out. You can watch the bleedout on the ammeter and pull fuses from beneath the steering column. As soon as you hit a circuit that is leaking your battery energy, and pull that fuse, the ammeter flow will drop way down, immediately. Pop the fuse back in, and the ammeter will jump up to a higher energy flow.

Now your problem is to do a wire trace to see what is connected to the offending fuse. Be glad your electrical system is better wired (I hope) than mine. I think the PO used the wiring in my Jeep to power the San Quentin electric chair!
 
Tinman22 said:
So with the neg disconnected and a volt meter between - post and - cable you get 0.
Click to expand...

Between (-) post and (-) cable, I get whatever voltage the battery is charged to (I hook it up to a charger until I work on it to keep power in the battery) and then it just gradually drops.

DHugg said:
Shotgun, I'm no electronic guru, but I do know that breaking the negative post loose and inserting a voltmeter is the same as dropping the negative cable and measuring volts across from POS to NEG post. You've broken the circuit and electrons can't glow.

I had a similar drain when my '80 CJ7 came home from the PO. Someone had installed a bar of floods above the windshield, and had made a wiring error that bled the battery out. I scrapped the floods, and the battery discharge went away.

What is needed to measure battery current flow is am ammeter. The ammeter will register how fast your battery is bleeding out. You can watch the bleedout on the ammeter and pull fuses from beneath the steering column. As soon as you hit a circuit that is leaking your battery energy, and pull that fuse, the ammeter flow will drop way down, immediately. Pop the fuse back in, and the ammeter will jump up to a higher energy flow.

Now your problem is to do a wire trace to see what is connected to the offending fuse. Be glad your electrical system is better wired (I hope) than mine. I think the PO used the wiring in my Jeep to power the San Quentin electric chair!
Click to expand...

I'm using a multimeter so I have a voltmeter/ammeter/ohmmeter all in one (plus more). I've read conflicting stories on which one to use but I wasn't getting any reading with the ammeter, even though it was showing voltage. My wiring is a little rough but I don't think it's anything I can't handle.

I'm fairly knowledgable about electricity and overall automotive tech... and I'm stumped. I guess I'll hold off until I have someone who can keep an eye on the multimeter while I
Pull fuses. This thing is really becoming a pain in my ***...
 
The test light is what I've always used to locate the source of a drain. Pull the right fuse or disconnect the correct accessory and the light goes out.

I can see the usefulness of measuring the amps going out of the battery but I'm a simple kind of guy. The light goes out equals no amps going out to me.
 
hdgapeach said:
The test light is what I've always used to locate the source of a drain. Pull the right fuse or disconnect the correct accessory and the light goes out.

I can see the usefulness of measuring the amps going out of the battery but I'm a simple kind of guy. The light goes out equals no amps going out to me.
Click to expand...

KISS !!! I made a test light with a 12V bulb with two soldered wires, one of which has a 10 kilo ohm resistor in line to keep current low. It is a weak enough light that I can detect changes in the electrical flow by how dim the bulb is, not how bright it is.
 
Atta boy! That's what I'm talkin' 'bout-----KISS!

Never quite figured out why I actually needed to know how many amps was going down the drain anyway. My goal was to have the bulb go out. Then I knew what I was dealing with. If the intensity of the bulb changed, I figured I may have more than one circuit involved with tryin' to sabotage my battery.
 
If you get a multimeter, make sure that it is rated to do DC amps (current). You want to be able to check current because any drain on the battery will show voltage (even a digital clock). A bulb works in a pinch, but they are not accurate, and if you have a high current drain then it will blow out the bulb. If you have a 10A current drain, you can kill a battery charge in a little over a day with a typical battery.

DHugg said:
Shotgun, I'm no electronic guru, but I do know that breaking the negative post loose and inserting a voltmeter is the same as dropping the negative cable and measuring volts across from POS to NEG post. You've broken the circuit and electrons can't glow.

I had a similar drain when my '80 CJ7 came home from the PO. Someone had installed a bar of floods above the windshield, and had made a wiring error that bled the battery out. I scrapped the floods, and the battery discharge went away.

What is needed to measure battery current flow is am ammeter. The ammeter will register how fast your battery is bleeding out. You can watch the bleedout on the ammeter and pull fuses from beneath the steering column. As soon as you hit a circuit that is leaking your battery energy, and pull that fuse, the ammeter flow will drop way down, immediately. Pop the fuse back in, and the ammeter will jump up to a higher energy flow.

Now your problem is to do a wire trace to see what is connected to the offending fuse. Be glad your electrical system is better wired (I hope) than mine. I think the PO used the wiring in my Jeep to power the San Quentin electric chair!
Click to expand...

This is correct. After you place the ammeter (multimeter) in series (between the neg. cable and neg. batter post), pull the fuses on at a time. If the multimeter does not show a drop, then it’s going to be in one of the non-fused lines. You will almost always show a very small ammeter reading (in the milliamps) but a short, or current drain, will be in the amps for it to drain a battery that fast. If it’s on a fused line, then run the wiring down. It takes a little time, but with persistence, it can be done.
 
Thanks for the input but I already have a decent multimeter, it just doesn't read DC amps. Unfortunate, I know, but I'd rather spend $4 at Harbor Freight for a test light, which I'm about to go do, instead of $20+ for another multimeter. I'm already $300+ into this Jeep and I've only driven it once in the past couple weeks I've owned it. I'm getting sick of dropping money on a vehicle that I can't even drive.
 
My favorite tool in the box of electrical stuff is the test light with a nice sharp point. I am always wanting a longer ground wire with the aligator clamp. Sure you can make'em, but the commercial units are so cheap and easy why not?
 
Found out that the PO had a Painless batte kill switch installed in the passenger side footwell on the firewall but was bypassed. I hooked it up and charged the battery, so I've been using the switch to keep the battery from draining. Would a starter going bad cause a drain? Took the Jeep to Home Depot and before I left it clicked the first couple of tries, like the battery was drained, and then cranked hard as if the battery was fully charged. When I went to leave the store it stumbled for a second and then turned over. I'm starting to think the issue is either in the start, starter solenoid, or ignition switch. The last one doesn't seem like the culprit though.
 
Sounds like a bucket full of electrical issues you're fixin' to deal with. The sporadic starting issue may very well be caused by battery cables, connections, or maybe solenoid grounding issues. It's possible for hard starting problems to be caused by a starter going bad. Are both battery cables in good condition (corroded, bad terminal ends, loose connections)? Clean the battery terminals and the cable ends. Then clean every connection location they are attached to (block, solenoid terminals, starter connection). Removing any doubt that you've assured good electrical connections helps when diagnosing wiring / electrical issues. Might as well convince yourself that you have good grounds throughout the system as well; ie- battery to block, block to frame, frame to body, body to battery.

The starter solenoid can stick and cause a drain. With a good battery that usually means the starter won't stop spinning whether the key is on or not. The PO probably installed the kill switch to prevent just what you're dealing with now rather than find and fix the problem.

Have you done the test light / fuse pull thing to determine if you can find a wiring circuit involved with the drain yet?
If you pull all fuses one at a time and none of them indicate a possible drain source, you'll need to start pulling un-fused connections that can be a source (usually underhood stuff like alternator wires and wiring coming off the starter solenoid, etc.). Unplug or disconnect a wire and place the test light between the wire terminal and the location you disconnected it from. If it's a drain source, the test light will illuminate. Then you gotta figure out if it's supposed to be hot. Keep in mind that anything coming from the hot side of the starter solenoid is going to give you a burning bulb if you ground the light.

If the PO added un-fused accessories like lights, winch or other gadgets, I think I'd start with those first. Seems like the PO might be the cause of what you have going on anyway.
 
Sorry you may have to download to a drop box account I can't load videos from my iPad.
 
Well, I think I found the issue. I had the kill switch hooked up and it was fine all day yesterday. Came home, turned the switch off. Went to get in it today, turned the switch on, and nothing. Just like the battery was dead again. I figured there was no way in hell that was the case, so I grabbed my rubber mallet and whacked the starter and solenoid. Turned the key and she fired up with every bit of 12V. I'm guessing my starter (or solenoid) has been on its way out and draining the battery trying to kick it loose when I go to start her.

Next issue that has popped up is that she doesn't want to turn off when I turn the key off. What's that all about? First she doesn't want to start and now she doesn't want to stop! lol
 
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