MacBook Pro Mid 2012 not charging above ~33%

[LeoBloom]

I have a MBP mid 2012 and I had replaced the battery from OWC/MacSales.com back in April 2022. I had since loaned the computer to a family member and just got it back a week ago. I initially noticed that when the device was charged to 100%, it would randomly shut down around 50% (+/- 10%), and would display 0% battery when I started charging it up again.

I have read that sometimes you need to reset the SMC, so I tried charging the computer up until the light turned from amber to green, shutting down the computer, removing the power adapter, and then pressing holding option/control/shift/power for 10+ seconds but it doesn't seem to fix my problem

I tried draining the battery overnight, and charged it for 8+ hours while I was away at work. The max it charged to was 33% and I let it deplete. The computer appropriately turned off at ~1%

I am running macOS 10.15.7. CoconutBattery says I am at 84.5% design capacity of the battery (5745 mAh/6800 mAh). It also states the manufacture date of my battery is 2022-01-04. It is showing 7 cycles, Good battery status, and that the battery manufacturer is Newer Tech

How can I fix the MBP so that it charges to 100% and shuts off appropriately at least <10%

 

[iMacDragon]

It's almost certainly got a bad cell

 

[LeoBloom]

Is there a way to verify this? What is the fix?

 

[iMacDragon]

behaviour like randomly shutting down tends to be a good indicator, if it is bad cell, there's not much that can be done.

 

[LeoBloom]

@iMacDragon OK thank you I will get a replacement battery

 

[ccbc]

What are you ordering?

I'm also looking to replace my battery on a MBP 13 mid-2012.

If I could find the same battery that I purchased in 2015, I would do it in a heartbeat. See below. Almost 13 years old with 726 cycles and I still can manage to get 4 hours out of it. Dynapack is a great battery manufacturer from my experience.

 

[LeoBloom]

I am re-ordering from the company because I have insurance coverage from the credit card for a free replacement. It was off MacSales/OWC