MBP shuts down when charge hits 80%

Thanks for the reply and diagnosis. Out of curiosity, what makes you say it's the battery? Just trying to understand.

I've had a laptop and two phones brought in with this problem before (they all shut off at their own percent), and all 3 times I replaced the battery and the customer was satisfied. If you're skeptical because this is something coming out of my personal knowledge rather than scientific backing i understand.

I wouldn't say that I'm skeptical. I just want to avoid throwing parts at the problem if possible. I'm happy to defer to those who have more expertise on these matters, though. I guess the thing that confuses me is that the computer seems to think the battery is in good condition based on diagnostic tests and the battery seems to have a lot of life left in it (only 281 cycles; that doesn't seem too high). Is it possible that there's some fault in the battery that the computer can't see? Again, just trying to understand what's going on.

@adman02 It could be a deterioration of the interior lithium lining of the battery, which would cause it to release the stored energy without the sensors picking up on it. Lithium Deterioration on batteries is generally caused by exposure to H20 compounds (Stuff with water in it) and extreme temperature (Like if you left your computer in your car when it was 10 or 110 degrees out).

Just to be clear, only two of the past orders my boss described were lithium deterioration. The other was just a battery that burnt out, but it didn't give any signs of normalcy like yours.