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MacBook keeps on turning off when unplugged, yet battery health is 86%

Hello Ifixit community, this is my first post. The problem is as follows:

My macbook air 13" Mid 2012 keeps on turning off abruptly when unplugged. It can last from anywhere around 2 minutes, to nothing (a small sound appears when powering on, yet cuts off even before booting sound). Initially it would last longer, yet quickly degraded to its current status.

However, when plugged in, it works with no problem at all...

I initially thought the battery must have degraded really, really quickly (i replaced it about 2-3 months ago), yet as can be seen with coconut, its in good health with realtively few cycles.

I hace done an smc reset with no results.

I have also done pram, no results.

I have run diagnostics, no faults appear.

I have attempted completely discharging battery, but as it turns off when unplugged, this is something I can not do.

What I am guessing (in light that the battery actually comes up as "good") is that the laptop somehow thinks that it is drawing too much power and thus automatically closing itself. When plugged, there is infinite power so it doesnt feel the need to close itself, even if it might see itself drawing too much power.

I think this might be the issue because the problem slowly started after very heavy usage of playing CIV 6 for a week where it was surely gobbling up power. Now the component that measures this "power-gobbling" (:)) rate is either broken or uncalibrated as a result of this heavy use.

But of course this is purely a guestimate...

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It would be much appreciated if someone helped me out!!

Answer this question I have this problem too

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Did you have a liquid spill at one point?

Do you spray cleaner on the system then wipe or do you spray the cloth then wipe?

by

Hi Dan, thanks for the response, I did in fact have a liquid spill, but this was waaaay back in 2013, when it was less then a year old. I was quick in getting it dry, and it continued to function normally.

As of cleaning, I dont this much (ie in average once a year), but when I do its probably spraying very lightly the mac itself...

The last time I did clean it was I think 3-4 months ago, but I didn't notice the closures after cleaning, rather with the whole CIV 6 week marathon

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Even though it was awhile ago spills tend to come back and haunt you ;-{ Spraying or getting the systems surfaces wet with a cleaner can drip into the system wetting things internally. Which is why I always recommend spraying the cloth Vs the system.

At this point I'm thinking some corrosion on the logic board is messing up the power control logic. Are you up to taking your logic board out and inspecting it for damage? Hopefully you can clean things otherwise iy may need someone with the skills and parts to fix your system

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Hi Dan,

I have previously changed the battery on my iphone, so I am a massive pro on these kind of things ( ;)) ). Ill watch some youtube videos and have a look at the board.

Many thanks for the response, and hopefully I can get it fixed :))

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Black Friday
Broken doesn't stand a chance.

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You mentioned that you had water damage a few years ago. My first thought would be that your previous damage is acting up again. If there was any corrosion around the ISL charging chip and it was not thoroughly cleaned after liquid damage, then now - years later + humidity + heat + any other variable could have cut the thread that was holding the system together.

If you are comfortable with it, I would recommend opening the system up and looking around the ISL chip and its resistors that is on the back side of your motherboard - with a magnifine glass or better yet, microscope.

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Damage can be easy or hard to spot.

It really sounds like a bad feedback resistor on the battery side of the power in circuit. If you do find damage here, you might want to consider sending your computer out for micro soldering repair, or if you are confident in your own skills and can get the right supplies, you can give it a go by your self first! There are some good videos on line showing what this chip does an how it can be replaced.

Good luck!

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As referenced before, this is the component and the resistors that first recieve the data on the power-gobbeling speed, then will send this to the SMC. If one of the resistors for the battery side of this circuit is having a problem/bad/corroded, it will give a false reading and thing it is gobbeling way to fast and shut the system off - The wall power side has its own resistors to sense this - and that is probably why it works fine on the wall power.

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@joesipaq - It's a Voltage comparator circuit.

I agree thats the likelihood!

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I'd try an SMC reset to start things off. This normally fixes standard battery issues.

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Hi Matt,

I have tried this many times, unfortunately did not fix (as i had said).

Thanks for the reply though!

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Ah, crap. Whoops. Alright, then. I'd be willing to bet that it's an issue with your laptop itself rather than the battery or macOS. Maybe a shot heatsink?

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Hi Matt,

The thing that really confuses me is that it runs perfectly when plugged.

Thus, the difference between it working and not is just whether it is plugged or not (not whether t heats up too much or too much demanding usage in terms of computing).

What I am guessing (in light that the battery actually comes up as "good") is that the laptop somehow thinks that it is drawing too much power and thus automatically closing itself. When plugged, there is infinite power so it doesnt feel the need to close itself, even if it might see itself drawing too much power.

I think this might be the issue because the problem slowly started after very heavy usage of playing CIV 6 for a weekwhere it was surely gobbling up power. Now the component that measures this "power-gobbling" (:)) rate is either broken or uncalibrated as a result of this heavy use.

But of course this is purely a guestimate...

by

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