Battery dead every 2-3 months

[garygbnj]

2010 LGT mt. 155k miles. Starting about 2 yrs ago the battery goes dead over nite. Only happens every 2-3 months. No lights left on, key is completely turned off. My mechanic has checked it out after I charged the battery and I even had it towed to his garage with out charging the battery. He was not able to determine what circuit had stayed on. The battery is fine (I had replaced it when the problem had first occurred). There is a Sony aftermarket amplifier installed but it is wired so that it only gets power when the key is on. The car has an STI trans and I love it. I do not want to get rid of it but the dead battery issue is a PIA. Any suggestions would be greatly appreciated. Thanks. Edited February 17, 2022 by garygbnj
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[Enlight]

I would YouTube videos on how to find a parasitic draw. Use a multimeter to find current on your fuses to see if anything is drawing more than it should. I would try the circuit that your amp is on first. Hopefully that will yield some clues.

 

You say this only happens every 2-3 months. How often do you drive your car? Intermittent issues are hard to pinpoint.

[garygbnj]

Thanks for the reply. The car is driven daily. I called Sony (Amp maker). The amp should be wired so that it only gets power when the key is on or in the acc position. If the amp was wired where the line was constantly hot then the amp would be on all the time and the battery would go dead every night. My mechanic has done the multimeter path with no luck on finding the draw. Gary

[Infosecdad]

This is gonna be a challenge to find if the parasitic drain only happens every 60-90 days.

 

That means the vast majority of your tests will not show the source of the issue.

 

That sounds like something is starting to fail. As long as the battery is newer and good, then it might be a relay that doesn't close on occasion or something like that. So, this has happened about 8-10 times over the last couple years. It's gonna be a challenge to catch it in action honestly.

[garygbnj]

I agree. It is a bear.

[Enlight]

Perhaps you can find the draw on a morning when you find it dead, before you've started the car and given the relays and switches a chance to reset themselves.

[garygbnj]

Tried that to no avail.

[Infosecdad]

I would consider periodically testing it at the end of a day when it's supposed to be all shutdown and see if you can catch it with a parasitic draw one night before the battery is drained. I would try testing every other evening for a month or so and see if you can catch it in the act.

[garygbnj]

Thanks

[Scubaboo]

That is going to be a challenge to find. Your only recourse may be to wait till it happens more often so you can get a chance to catch the offending part.

[whitexc]

Install a master switch/disconnect on the battery. While a pain to have to do, at least it wouldn't kill your battery.

 

Sent from my SM-G996U using Tapatalk

[Enlight]

PriorityStart! makes a product that disconnects your battery if the voltage falls below 11.7 volts. As I understand it, it's an operation free product that will restore the connection when you start your car.

[silverton]

Or get a remote starter with a voltage safety in it. Mine will start the car at a pre-set low or high temperature and/or battery voltage.

[Scubaboo]

Or get a remote starter with a voltage safety in it. Mine will start the car at a pre-set low or high temperature and/or battery voltage.

 

You mean it can be programmed to start the car if the voltage gets low enough, so it can charge?

[garygbnj]

Thanks to all for the information. Gary

[stewdogg]

Is there a possibility the trunk light is staying on somehow? Maybe pull the bulb and see how the next 4 months go...?

 

I hope it's the trunk light over a parasitic drain, those suck to find normally and worse when they're a random issue.

[moral hazard]

You don't have anything connected to the obd port by chance?

 

I had a Bluetooth scanner that would slowly drain the battery.

[garygbnj]

I just ordered a Priority Start unit. That should solve the problem as it is next to impossible to pin down where the draw is coming from. I never heard of a unit like the Priority Start. Thanks so much for the information.