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This question already has an answer here:

I have a MacBook Pro Mid 2010 that I changed the battery and logic board on, a few moths ago.

I have an issue with the battery that after a full charge and removing the charger plug the battery suddenly drops below 80%, but runs normal till about 50% and then the MacBook suddenly shuts down and doesn't turn on again until I plug the charger in again.

I've tried reseting SMC and calibrating the battery with no result.

CoconutBattery dialog

marked as duplicate by Allan macbook May 5 at 18:07

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    Welcome to Ask Different :) Did you try resetting the SMC? – Nimesh Neema May 5 at 14:26
  • @Allan: You've closed this, indicating the Q has been asked & answered. However, the OP for this question stated, I changed the battery and logic board on [it] a few moths [sic] ago. The answers for the question to which you gave precedence seems to be all about older batteries. – Seamus May 5 at 23:55
  • @Seamus - the problem can manifest on new batteries as well. Just because it’s new doesn’t mean it cant fail – Allan May 6 at 0:02
  • @Allan: If you say so, but that's a difficult thing to prove under these circumstances, would you agree? – Seamus May 6 at 0:05
  • @Seamus - it’s very easy to prove; swap the battery. You have to understand there’s nothing in the OS or on the Laptop that can physically measure each cell. So, unless you want to spend hundreds of $ on a battery diagnostic tool, the easiest and cheapest way to solve this is to swap the battery – Allan May 6 at 0:40
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Apple has better diagnostics than third party plug in, so I would seek a quote / evaluation from AppleCare online or a store if that’s more convenient.

The shutdown at 50% should be logged well enough for them to diagnose if you need another battery since that’s exactly what happens when one cell is failing or behaving like the other cells and the predictive model of how much charge is left doesn’t accurately tell you how much run time is left.

Over time, I would expect the battery status to go to check battery or replace battery if it’s the battery that’s failing.

It could be the logic board, too but that’s far less likely. Only swapping one and not the other will let you test which item is causing the discontinuity.

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You might want to have a look at the power management system's logs. There may or may not be something useful in there, but it's free and easy to do - so why not?

You can run pmset from a terminal window; it has a number of options, and they are documented in the system manuals. You can peruse the pmset manual as follows:

$ man pmset

To get right to viewing the output, you might want to first check the battery status, then watch the raw log for a bit:

$ pmset -g batt            # battery status
$ pmset -g rawlog          # monitor log; use ^C to stop & return to cmd prompt

Your output may look something like this (from my system, a 2016 MacBook Pro):

$ pmset -g batt 
Now drawing from 'Battery Power'
 -InternalBattery-0 (id=4391011)    61%; discharging; 3:27 remaining present: true
$ pmset -g rawlog
pmset is in RAW logging mode now. Hit ctrl-c to exit.
 * Battery matched at registry = 7171
05/05/19 18:19:35
 No AC; Not Charging; 65%; Cap=4083: FCC=6197; Design=6669; Time=3:55; -1042mA; Cycles=285/1000; Location=0; 
 Polled boot=05/05/19 17:55:34; Full=05/05/19 18:15:34; User visible=05/05/19 18:19:34
05/05/19 18:20:34
 No AC; Not Charging; 65%; Cap=4077: FCC=6206; Design=6669; Time=4:27; -917mA; Cycles=285/1000; Location=0; 
 Polled boot=05/05/19 17:55:34; Full=05/05/19 18:15:34; User visible=05/05/19 18:20:34
05/05/19 18:21:34

Perhaps the most useful item in the rawlog display is the current consumption:

-1024mA

An abnormal current draw may suggest a system issue; otoh, a "normal" current draw may suggest the battery itself is the issue.

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