Battery Keeps Dying

[brent0252]

Hello,

My battery on my 2000 Montero Sport keeps dying. The first time it happened we jumped it off and took it to WalMart to get a new battery because this one was still under warranty. Got a new battery and 7-10 days later, died again overnight. Took it back and got another battery and 7-10 days later it died once again overnight. We did this one final time and I did not turn on the radio or anything on in the car and it died in 7-10 days once more. We tested the batteries and they were holding charges and we have already replaced the alternator about a year ago. Took it to AutoZone and they tested the car and everything passed, including the alternator. We also took it to another mechanic who did the lightbulb test on the battery and it passed that test that nothing was drawing the battery.

Any ideas on what the problem could be? Like I said, even with a brand new battery and nothing on in the car, the battery will be completely dead in 7-10 days. Alternator and starter have been replaced a year ago and passed testing.

Thanks,
Brent

[picaflor]

that remembers me when i had that problem... at the end my problem was the battery, which doesnt seem to be your case, but in those days, i ended installing a $1 ebay voltimeter like this :



in the space for the garage opener to be able to know how many volts the battery had when i started the car, drove the car, turn on lights, ride at high rpm or low rpm, etc. you may want to install one of those to help you pinpoint the problem.

now i know that my battery is like 12.5v in the mornings, when driving it is normally 14.2. It use to be 13.6, but after connecting my 2 year old battery to the battery tender for one night, now normally stays in 14.2 when driving.

maybe some stuff that you connect or put in the car is eating the battery (using more watts than what you produce) when you use that? cigarrete lighter? subwoofer? amplifier? extra lights? trailer? hid lights?

[bahnstoermer]

I had a similar problem that I caused, then fixed myself. I bought a different group size battery (more CCA) than standard, but it was shorter. I put a piece of wood under the battery so that the fastener would still tighten down on it. This raised the battery in the vehicle.

Amazingly, only about 3/4" raise caused it to push into the hood, and through the rubber cap on the battery it was draining into the hood. This is scary, because if it wore all the way through and dumped 700 CCAs into the hood, it could have caught fire.

Once I figured this out, the block of wood was cut to go on top of the battery instead of below, lowering the battery, no longer touching the hood, problem gone. LOL. Sometimes doing it yourself is risky. Be careful modifying!

[kumachn]

Is the alternator a refurbished alternator or newly manufactured ones. Refurbs. tend to go bad fast. Also try disconnecting the battery while the car is running. If the car turns off or is struggling while battery is disconected your alternator is not working properly.

[brent0252]

I have the right size battery in the car. I have gone through 3 new batteries. I get no warning signs of the battery about to die each time it happens. I just try to start it and it will make the *ding ding ding ding* noise when you turn the key and that noise fades and dies. The car makes no sounds when I try to turn the key or anything. When the alternator went out over a year ago it just had trouble turning over, that's not what is happening now. I haven't installed anything new on my car for 6 months before this started happening. I even tried with the last battery disconnecting my amplifier and not using my cd player etc to see if that solved it, but it did not.

[Joel_CA]

You need to do a parasitic draw test at the battery negative. This checks to see how much current draw remains after the key is turned to the off position and everything eventually powers down. You should have no more than 50mA draw. If there is more than this amount- isolate the circuit that the draw is coming from by pulling fuses out of the fuse box one at a time (replacing the prior fuse before moving onto the next). Every circuit in your car runs though a fuse of fusible link at one point or another. If you pull the fuse to the circuit that remains powered- the current draw will drop significantly and you'll know where to start looking.

JJ

[dclambertt]

Reviving an old thread. My battery is dying as well, but I seem to have located the fuse to the problem circuit. I pulled the fuse for the interior lights, but there are more devices than interior lights running through that fuse.

It powers the overhead lights, console lights, door lights, radio, clock, power door locks and security system. The tranny seems to be have trouble relearning proper shifting as well.

With this 10A fuse pulled the battery has performed perfectly for weeks.

Would love any suggestions on where to start looking with this many affected circuits. Thanks!

Dan

[Naeos_Valkarian]

Dec 16, 2019 23:06:20 GMT -5 dclambertt said:

Reviving an old thread. My battery is dying as well, but I seem to have located the fuse to the problem circuit. I pulled the fuse for the interior lights, but there are more devices than interior lights running through that fuse.

It powers the overhead lights, console lights, door lights, radio, clock, power door locks and security system. The tranny seems to be have trouble relearning proper shifting as well.

With this 10A fuse pulled the battery has performed perfectly for weeks.

Would love any suggestions on where to start looking with this many affected circuits. Thanks!

Dan

Check the 40A fuse located in position (8) for the battery. If that one is corroded, it could be causing charging issues. Also check the fuse for the reverse lights under the dash as this one can cause some weird tranny issues if it's bad. When mine went out the tranny went into limp mode.

I'm also assuming you've had the alternator tested, it could be new and still be bad. Source: I sell car parts.

Underhood fuse box diagram:

[dclambertt]

Thank you Nine. The alternator performance tests fine, and yet this is the third battery to fail over a couple of weeks of testing on each battery with the 10A fuse installed. I will pull the 40A and the other one you mentioned and post back.

[dclambertt]

Well I'm back.. with the same problem. I had fuse 1 out of the truck for a month or so, put it back in and the truck started perfectly until a couple of weeks ago. Battery died, charged it overnight, went to start a day or so later and the battery was dead again. Pulled the fuse 1 out after recharging the battery, and once again the battery stays charged and the truck starts like it has a new battery. If I recall I did check the fuse 8 and saw no corrosion, but I'll check it again. It's crazy that so many features are run through that 10 amp fuse! Anyway, it seems like something got fixed when I pulled that fuse out for a month, like a relay or something finally started working properly.

[Naeos_Valkarian]

Sept 14, 2020 16:25:05 GMT -5 dclambertt said:

Well I'm back.. with the same problem. I had fuse 1 out of the truck for a month or so, put it back in and the truck started perfectly until a couple of weeks ago. Battery died, charged it overnight, went to start a day or so later and the battery was dead again. Pulled the fuse 1 out after recharging the battery, and once again the battery stays charged and the truck starts like it has a new battery. If I recall I did check the fuse 8 and saw no corrosion, but I'll check it again. It's crazy that so many features are run through that 10 amp fuse! Anyway, it seems like something got fixed when I pulled that fuse out for a month, like a relay or something finally started working properly.

This video helped me find my parasitic draw, www.youtube.com/watch?v=KF1gijj03_0

Turned out my AMP and radio were both still drawing power even when they "turned off", installed a relay and had no more issues.

[dclambertt]

Thanks Naeos. As I mentioned I know precisely which fuse is causing the draw, but not which component in that circuit is the culprit. Do you have an aftermarket radio installed? Mine is stock original. It's just odd that if I pull the #1 fuse in the engine bay and leave it out for a few days, the circuit behaves properly. Then just when I really need to use the truck the battery dies.

[Naeos_Valkarian]

I don't have much experience with 2nd gen sports but I'm assuming the fuse box is still relatively the same, if this is true then the #1 engine bay fuse is for the dome lights. charge the battery, install the fuse and see if all your dome lights are working. Assuming they all work fine, I'd check to see if one of them is acting as a ground at all times. I had a brake light bulb partially fail and it bridged the second filament to the first one which caused all kinds of electrical issues.

[jkdv8]

That’s technically the ETACS fuse. The circuit feeds the ETACS and all those circuits are controlled from there. It’s more than likely one of the individual circuits you mentioned but just something to throw out there. Check the map light circuits. Each door switch, including the switch imbedded in the tailgate latch. Make sure the security light starts flashing a minute or so after it’s engaged. If there is a power antenna, make sure it’s not continuously running and if it has the infinity system check that the amp is switching off along with the radio.

[dclambertt]

Thanks guys. Sorry to respond so late. Here's a new wrinkle.. both 12V accessory ports are dead, even if I reinstall engine bay fuse 1. I wonder if they're the culprit somehow. Not sure which fuse controls them.