Parasitic battery drain

BobK

BobK

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What is the best way to determine what could be causing a parasitic battery drain?

Admittedly, I only drive my TJ once a week or so, but on repeated occasions I have to use my Jump Box to get the Jeep started. A few weeks ago in trying to diagnose the source of the problem I disconnected my winch from the positive battery terminal, thinking that it was causing the issue, but then again tonight the battery was dead after driving it for an hour or so two days in a row last week. Surely a battery that has been tested by both Auto Zone and O'Reillys and found to be in good shape should be able to hold a charge for a week. That leaves me with the assumption that some other accessory must be drawing just enough current to kill the battery. Thoughts in source and/or a method to track it down.
 
This is the video I referenced when searching for a parasitic drain in my Land Cruiser and he does a great job explaining.

Ultimately, it turned out to be the CD player. There was a disc stuck in the magazine and the player just kept spinning. I would check if you have an aftermarket alarm system or head unit especially if it has Bluetooth.
 
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That is an excellent video and resource for where to start. The meter comes out tomorrow and I have a few guesses what it might be, but I'll wait for the "official" results of the test.
 
In the old days before computers and advanced electronics, we used to use a test light between the battery cable and battery post. The amp meter is a better idea.
 
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Chased a parasitic draw for quite some time with no success. Ended up using this USA sourced 'night switch' . . . My '04 is completely stock electrically with no winch. The OEM radio will retain the station selections, but you'll have to re-set the clock. Mine would drain off over a three week period. Not any more. The ideal set-up would be a hidden switch.
 
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All vehicles have some parasitic draw and you need to determine if yours is abnormal. If you're one that doesn't drive the vehicle much I highly recommend a battery tender (not a charger). A vehicles alternator is not designed to charge the battery to 100% and may be part of your problem.

I hardwired this tender into my vehicle and have the connector coming out the front of the grill to make plugging it in super simple. I also use a tender on my RV batteries and my F-250 with dual batteries, neither of which get much use. When I do use them they start as if the battery (s) were brand new.

https://www.amazon.com/dp/B000CITK8S/?tag=wranglerorg-20
 
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First, make sure your battery is healthy/fully charged.

Then use an amp meter in line at your negative battery cable (one lead to the cable while disconnected and one to the battery terminal). Make sure everything is off including interior lighting before connecting the meter or you may pop it’s fuse.

I’m not sure what the acceptable draw for a TJ is at rest - maybe somebody can chime in? Most vehicles I work on are 40 milliamps or less.

If you find anything above that, I like to begin probing each fuse with a voltmeter. You’ll see tiny metal tabs next to the fuse rating on the fuse itself. Put a lead on each one of those and move from fuse to fuse.

You should see zero. If there is any current passing through the fuse, you will get a voltage reading.

Remove the fuse and see if your current draw drops on your amp meter.

That’s how I find draws as a tech on the line and I’ve found it works quite well.
 
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Thank you all for your input. This morning I went out to start the Jeep, but since I had only jumped it and let it run for a few minutes last night, the battery wasn't charged enough to start it.

You may have seen another thread I started last night about an unusually high RPM at start. Many comments were made about checking vacuum lines (all of which had been replaced last year) but one comment about the PCM made some sense to me, so I disconnected the ground from the battery for 15 minutes or so. Then I reconnected the ground to the battery and jumped it. The engine turned over and came to rest at its normal idle, which solved the high RPM issue by resetting the PCM.

At this point, I have attached my trickle charger to the battery to get it to a full condition. I did do a preliminary amp check by putting my amp meter across the negative terminal on the battery and the disconnected ground wire and only found a 30 milliamp draw. Although I have a theory about what may be causing the parasitic drain. I have a bluetooth dongle that is supposedly for sending OBD info to my Insane Audio radio for diagnostic purposes. Honestly, I rarely if ever even look at that screen on the head unit, so I pulled the dongle before I even tried to start it.

Once the battery is fully charged, I will do another test for amps being drawn while the vehicle is off and sitting quietly....more to come.
 
I wouldn't worry much about parasitic draw if it's under 100 milliamps. It would take a long time for 100 milliamps to drain a healthy battery.
 
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I guess the battery can be in good condition, but it the alternator isn't charging it, then the battery would always be weak enough that it wouldn't start the Jeep. How do I test the alternator? The gauge in the Jeep seems to indicate 14 volts of charging while running/driving.
 
While you may be able to get the battery voltage up to what appears good....
As soon as a load is placed on the battery, no matter how little....; the battery voltage will drop quickly.
Place a smart battery charger on the battery over night; I suspect the charger will tell you the battery is bad.
 
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This has been a continuing problem for the past several months. I have taken the Jeep to both Auto Zone and O'Reilly's a couple months apart, with the plan to buy a new battery only to have them test the battery and determine that it was in good shape and only needed to be charged.
 
BobK said:
This has been a continuing problem for the past several months. I have taken the Jeep to both Auto Zone and O'Reilly's a couple months apart, with the plan to buy a new battery only to have them test the battery and determine that it was in good shape and only needed to be charged.
Click to expand...

Find someone that will loan you a known good battery and install the battery in your Jeep. Try starting the Jeep the next morning and see if the problem still exists....
If the instrument cluster volt meter indicates 14V when running; test the voltage on the battery terminals with a multi meter to verify the battery voltage. Turn the engine off and watch the battery voltage readings to see how fast it drops and to what amount it settles at.
 
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CharlesHS said:
While you may be able to get the battery voltage up to what appears good....
As soon as a load is placed on the battery, no matter how little....; the battery voltage will drop quickly.
Place a smart battery charger on the battery over night; I suspect the charger will tell you the battery is bad.
Click to expand...

On a smart charge now, instead of the trickle charger I had it on. It is currently reporting 12.5 volts, 50% charged, and is taking the full 1.25 amp charge.
 
I have also just ordered a trickle charger that I'm going to wire into the Jeep and put on the trickle charge more often. Once the battery is fully charged, I will do an amp test again to ensure there are no parasites drawing current.
 
BobK said:
I have also just ordered a trickle charger that I'm going to wire into the Jeep and put on the trickle charge more often. Once the battery is fully charged, I will do an amp test again to ensure there are no parasites drawing current.
Click to expand...

A trickle charger or a battery tender? There is a huge difference. A trickle charger continually charges the battery at a trickle rate. This in time will ruin your battery. A tender maintains the battery at just under full charge by stopping the charge and restarting it when needed .. normally when it hits 90%.
 
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BobK said:
I guess the battery can be in good condition, but it the alternator isn't charging it, then the battery would always be weak enough that it wouldn't start the Jeep. How do I test the alternator? The gauge in the Jeep seems to indicate 14 volts of charging while running/driving.
Click to expand...
What I did to rule out the alternator without taking it anywhere was to drive the vehicle everyday for a week after initially jumping the battery and then let it sit for a few days. If driving it daily was just enough to charge the battery for the next day, it looked like the alt was okay. But if I skipped 1 or 2 days, the battery would be dead suggesting a draw. Admittedly not the most scientific but it seemed to make sense at the time.

3ma doesn’t sound like a lot but I have gone 3 plus weeks without touching my Jeep and it starts right up. There’s no alarm, power locks, gps, or Bluetooth to really draw any power when the vehicle is off so the draw should be negligible. Make sure you are using the lower ohm setting to get the most accurate reading.
 
After leaving the battery charger/tender on overnight, the charger indicated a 100% full charge and was displaying 14.5 volts. After disconnecting the charger and using my volt meter, the battery was indicating 13.1 volts, upon starting the Jeep, the meter read 13.9 volts.

I then shut it off, disconnecting the ground terminal and used my amp meter setting to look for any parasitic draw. On the 20 amp setting, I had an immediate reading of .3 that reduced to .1 in a second or two. If my math is correct, and I'm not saying it is, that would indicate between 100 and 300 milliamp draw. Is that correct? Is that too much?
 
Are you sure there is a 20 amp setting? I am assuming 10 amp in which case 100 milliamps is correct. I think that is too high going by the 50 milliamp threshold. I remember testing my Jeep and it was actually much lower than that as you can imagine. I would start pulling some fuses to see how close to zero you can get it. Alternatively, you can also just disconnect whatever you think the offending component is and see if that helps.
 
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