Hey everyone. So I purchased a new 800/1000 amp battery for my xj. I have had it tested at 3 different auto parts stores and they all say it is fine. I got the new battery because the one that was in there was dead every morning. I have unplugged my radio and power locks but every morning after sitting for 15-16 hours the battery is dead again. If I disconnect the battery and hook it back up in the morning it is fine. What could be draining my battery?
New battery won't hold charge?
- Thread starter outracing
- Start date
dan1977p
NAXJA Forum User
- Location
- Virginia Beach, VA
Time to pull out a volt meter and start tracing wires until you find the one that is drawing more than it should with the car off. That and looking for wires that have their shielding worn off and are grounding to the chassis.
old_man
NAXJA Forum User
- Location
- Loveland, Colorado
For the draw to pull down a fully charged battery, it has to be a above 5 amps of so.
First, turn off the engine and remove the key. Get a multimeter that can measure 20 amps or so. Set the meter to measure that much current and make sure the leads are plugged into the correct inputs on the meter.
Disconnect the positive terminal on the battery. Connect the meter between the positive post on the battery and the cable you disconnected. Quickly take a look at the current draw. Make sure it isn't pulling over 20 amps or you could blow the fuse in your meter.
Verify that the meter is reading at least some current.
What you have just done is to set up the meter to measure all the drain on the battery when the vehicle is turned off. Place the meter where you can read it or have some read it to you for the next steps.
The quickest method is to unplug each fuse and plug it back in one at a time. Any change in the reading will represent the current being drawn in that circuit. For reference, normally the max current drain on the battery should be no more than .1 amps.
Walk through each fuse. You should see one fuse that has a ton more draw than the others. That will put you on track for finding the problem.
Historically, a bad switch on a glove box light or a door switch that keeps the dome light on are the culprits, but you never know. Another thing that could be causing the problem is the ASD relay (Automatic Shut Down). It is designed to keep power on the computer for a few seconds after you turn off the key, giving the computer time to reset the Idle Air Controller to have it ready for the next time you start.
When the key is off, there are not that many things that should remain powered up. Doors and lights are the main things. A small amount of current will be used to keep the memory alive in the ECU, but it should only be a few milliamps. If you have a clock, at a few milliamps. You could have an aftermarket radio hooked up to the wrong (unswitched) 12v. Some radios have an unswitched input for keeping a clock in the radio running, but again, it should be a few milliamps.
A bad switch in the wipers, that powers them to go to the parked position after you turn off the key could cause the issue, but you would most likely hear the motor running. In the worst case, put your hand on the wiper motor. If it is drawing enough power to drain the battery, it should be somewhere between warm and hot.
Maybe check the rear winder defogger if you have one. Again, to drain the battery you are expending considerable energy, which should show up as heat somewhere.
A stuck brake light switch can also draw considerable power, but you most likely would have noticed that.
I had a bad motorized antenna on my Explorer and it went bad and did the same thing. The motor seized but the fully retracted switch didn't get hit so it never turned off the power to the motor.
A bad diode in the Alternator can cause a ton of draw.
Good Luck.
First, turn off the engine and remove the key. Get a multimeter that can measure 20 amps or so. Set the meter to measure that much current and make sure the leads are plugged into the correct inputs on the meter.
Disconnect the positive terminal on the battery. Connect the meter between the positive post on the battery and the cable you disconnected. Quickly take a look at the current draw. Make sure it isn't pulling over 20 amps or you could blow the fuse in your meter.
Verify that the meter is reading at least some current.
What you have just done is to set up the meter to measure all the drain on the battery when the vehicle is turned off. Place the meter where you can read it or have some read it to you for the next steps.
The quickest method is to unplug each fuse and plug it back in one at a time. Any change in the reading will represent the current being drawn in that circuit. For reference, normally the max current drain on the battery should be no more than .1 amps.
Walk through each fuse. You should see one fuse that has a ton more draw than the others. That will put you on track for finding the problem.
Historically, a bad switch on a glove box light or a door switch that keeps the dome light on are the culprits, but you never know. Another thing that could be causing the problem is the ASD relay (Automatic Shut Down). It is designed to keep power on the computer for a few seconds after you turn off the key, giving the computer time to reset the Idle Air Controller to have it ready for the next time you start.
When the key is off, there are not that many things that should remain powered up. Doors and lights are the main things. A small amount of current will be used to keep the memory alive in the ECU, but it should only be a few milliamps. If you have a clock, at a few milliamps. You could have an aftermarket radio hooked up to the wrong (unswitched) 12v. Some radios have an unswitched input for keeping a clock in the radio running, but again, it should be a few milliamps.
A bad switch in the wipers, that powers them to go to the parked position after you turn off the key could cause the issue, but you would most likely hear the motor running. In the worst case, put your hand on the wiper motor. If it is drawing enough power to drain the battery, it should be somewhere between warm and hot.
Maybe check the rear winder defogger if you have one. Again, to drain the battery you are expending considerable energy, which should show up as heat somewhere.
A stuck brake light switch can also draw considerable power, but you most likely would have noticed that.
I had a bad motorized antenna on my Explorer and it went bad and did the same thing. The motor seized but the fully retracted switch didn't get hit so it never turned off the power to the motor.
A bad diode in the Alternator can cause a ton of draw.
Good Luck.
Last edited:
HEP111
NAXJA Forum User
- Location
- Depends on whos asking
