Macbook Pro sudden shut down when on battery power

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Level 1

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Macbook Pro sudden shut down when on battery power

I have a 17" Macbook Pro mid 2009, 2.8GH with all original components and very good battery (only 350 cycles). I've recently noticed that the computer shuts completely down randomly, only when on battery power, works completely fine with charger. My macbook is in pristine condition and never been abused as it was used as a secondary desktop computer always plugged in, except every now and then I would completely discharge and recharge a full cycle.It shuts down mostly when battery is below 65%. The screen just go black and the all computer shuts altogether with a clicking sound. Do you know what it could be? I took the cover off to take a look at it and cleaned the vents, disconnected and reconnected the battery, all seems in really good shape inside. I did an SMC reset but didn't help. I even try to connect a brand new battery (just in case) but that didn't help too.

Anyone as a clue?

Thanks

MacBook Pro 17″, OS X 10.11

Posted on Sep 30, 2020 9:19 AM

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Answer 1

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neuroanatomist

Level 9

50,359 points

Sep 30, 2020 9:28 AM in response to valemod

350 cycles does not mean your battery is very good. Age is a big factor in battery lifespan, regardless of how much the battery is actually used, and 11 years means your battery is geriatric. Replace the battery then reset the SMC. Make sure you buy a quality battery (which is hard, Apple no longer makes them and many 3rd party sources aren't reliable).

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Answer 2

valemod Author

Level 1

8 points

Sep 30, 2020 12:21 PM in response to neuroanatomist

neuroanatomist thank you very much for your comment. I actually forgot to mention that my MB Pro would stay on the whole time, even on battery power, if I don't mess around with the laptop, for example, if I watch a YouTube playlist of many hours without touching the Mac and doing anything else, it will always stay on until the battery is completely drained and, man, it last so long! probably 6 hours or more (considering its age, that's better than my 2015 MB Pro!). So if it was the battery, it shouldn't always work in this specific circumstance (hours of YouTube), right?

It will only shut down when I do things, not necessarily power consuming things, even just messing around with folders.

Sometimes it will shut down right after starting the Mac.

I will try a different new battery as you said and reset the smc after new battery is installed.

However, if you can think of anything else, after this new info, please let me know. I kinda suspect the worse: Tantalum capacitor gone bad?

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Macbook Pro sudden shut down when on battery power

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