Battery drain saga

I’ve been chasing dead battery’s for several weeks now. This evening i started some testing and need some help. 1988;JD 2555 diesel. Both battery’s have their ground straps removed. I put the multi meter between the negative post and the ground strap and get a 4 volt draw with all the alternator leads disconnected and the key off and removed. I removed all the starter leads and get the same 4 volt draw with everything off and disconnected. When I began replacing wires one at a time I did not see a change until the power (hot) lead was reconnected to the alternator and I began to see an amp draw jump to 10 amps that counted down to and stayed at 4 amps in the key off position. I have not looked any farther or pulled any fuses yet to see if I can cut off the 4 amp draw. I have not checked the leads on the ignition solenoid yet. Any idea what might be going on with this thing.
 
(quoted from post at 23:39:58 01/12/18) Don't you think you may have a bad alternator?

I may, I had the 4amp draw with the alternator completely disconnected. It went to 10 amps when the wires were reconnected and clocked back down to 4 amps in about 5 seconds. I think that was the diodes discharging. I’m still thinking this through. The 4 amp drain with the alternator and starter disconnected leads me to believe there is another issue to find
 
Hook everything back up but the grounds. Put your meter in the ground circuit. Then remove fuses one at a time to see if you can get the draw to stop. Then just identify what that fuse runs and you can usually trace the trouble. IRC the fuse panels is behind the left side cover under the battery box.
 
(quoted from post at 02:01:50 01/13/18) Hook everything back up but the grounds. Put your meter in the ground circuit. Then remove fuses one at a time to see if you can get the draw to stop. Then just identify what that fuse runs and you can usually trace the trouble. IRC the fuse panels is behind the left side cover under the battery box.

I will give that a shot. Will just need to find the chart to identify the fuse location to the circuit affected
 
Wilderide47, before any conclusions can be drawn I think we need to clear some things up first. Your approach is good but we need to establish what you?re measuring. If you actually have your meter on volts and you?re measuring between the battery ground post and the disconnect ground cables you are just measuring floating/stray voltages that mean pretty much nothing.
In the test configuration you described you should have your
meter on amps. Does your meter have a low amp setting and
or a shunt probe? I suggest you pull out your meter
instructions and see if it has any current measuring means. If
you don?t have the instructions perhaps you could post the
mfg and model of the meter.
Once you are sure you are measuring current flow, then you
can start pulling fuses, etc.
Good luck. I look forward to learn more about your meter and test configuration.
Paul
 
"I opologize, should have typed volts. I only have a multi meter to test with. Didn’t want to confuse the topic"

A 4 "VOLTS" reading with a likely sensitive meter literally means NOTHING 'cause even with a good-working system, you will likely see some VOLTS, doing it that way.

You need a MILLIAMPS reading, or try this... disconnect one of the battery cables and connect an unpowered 12 Volt test light between the battery post and the disconnected cable, and note if it lights, or glows dimly, might have to dim the light, or wait 'til dark to see it if it's a real low draw causing a very dim glow of the light.

If it glows at all, disconnect stuff 'til it quits glowing, thereby identifying the source of the battery drain..
 
I would say you have a bad isolation diode . Should be no load from the alternator when stopped . This will run the battery down, alternator should be warm to the touch the next day if it is a bad diode .
 
(quoted from post at 09:29:14 01/13/18) Wilderide47, before any conclusions can be drawn I think we need to clear some things up first. Your approach is good but we need to establish what you?re measuring. If you actually have your meter on volts and you?re measuring between the battery ground post and the disconnect ground cables you are just measuring floating/stray voltages that mean pretty much nothing.
In the test configuration you described you should have your
meter on amps. Does your meter have a low amp setting and
or a shunt probe? I suggest you pull out your meter
instructions and see if it has any current measuring means. If
you don?t have the instructions perhaps you could post the
mfg and model of the meter.
Once you are sure you are measuring current flow, then you
can start pulling fuses, etc.
Good luck. I look forward to learn more about your meter and test configuration.
Paul

I was using my Fluke T5-1000. It does not have DC amps. I pulled out my Motorola meter and it does DC amps, just need to pick up some batteries this evening and I can give it another shot and see what the results are. Thank you for catching the method failure. Checking for amp follow will be interesting to see what’s happening
 
Sounds like a good plan Wild. Bob had an interesting idea. I just don't know how low a current a bulb will show any glow, depends on the bulb.

Paul
 
(quoted from post at 20:31:57 01/13/18) Sounds like a good plan Wild. Bob had an interesting idea. I just don't know how low a current a bulb will show any glow, depends on the bulb.

Paul

Ok, this evening I got out to the barn and tested the battery’s with the dc amp setting. Interestingly, since I’ve had the ground straps disconnected the trickle charger has brought both batteries up to charge and has held them steady.

The amp meter was connected between the ground post and the ground strap with the alternator disconnected. The meter did not shows Sustained draw. The meter came up as 0.00 in the 300 ma setting. It opted up as 0.01 and dropped back to 0.00 and stayed there. I tried at the second battery and ground strap and had the same results. After reconnecting the alternator and retesting I had the same results 0.00 a blip at 0.01 and right back to 0.00 and stayed there. I rechecked the battery positive cables, ground strap and the lines running to the alt and the started. All ohm out as good solid continuity. I was told by the dealer that would guess there is a starter short when starting and said I should talk to a local Shop that can rebuild the starter. After. Speaking with them they recommend testing the alternator. I’m stumped, doesn’t seem like I have an amp draw while doing these tests but something sucks the life out of the batteries when the grounds are connnected. Dealer and local shop are pointing fingers at components. I’m thinking I need to find someone that can test the alternator when off the engine even though I get 14 volts when the engine is running. When the charger is back on the batteries after running for an hour it needs charging. The starter will turn the engine fine with freshly charged batteries and if restated shortly after running the engine. Give it time to cool off in 20F temps and the solenoid starts clicking. I’ve done so many charging system fixes on cars but this green lady has my goat.
 
If anyone has any recommendations I sure would be happy to hear them. I think I’m going to start withtaking the alternator to a shop and have it bench tested.
 

The momentary slight drain after connecting the batteries is just charging a capacitor.
There is either an intermittent fault or operator error draining the battery. I have seen the light switch turned the wrong way to the last position . Instead of turned all the other way to the OFF position. Causes a slow drain.
 

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