MBPr (mid 2012) replaced battery - >50% shut down

[Rene Reicher]

Hi there,
First of all I want to thank everybody, who is patiently helping people in this forum to fix their problems. I managed to fix many problems using this knowledge base. Now I have a problem, that I am not able to fix using this site:

What has happened:

• My MBPr (mind 2012) kept shutting down without warning at 23% together with a battery maintenance request
  
• not willing to spend 200€ on a 5 year old MB, I decided to replace the battery on my own
  
• with a guitar string (nylon) I was able to cut free those batteries and replaced them with this.

Problem:

• first the battery was not charging (for maybe 1 day), but running from mega safe was possible
  
• then the battery charged but only to 87%
  
• now the battery shows 100% (with mega safe) and ~95% without. Battery works like a charm until it hits the 50% mark. Between 45-50% the MB shuts down without warning.

What I tried:

• I reset my SMC a couple of times without any effect.
  
• I found something about calibrating batteries but there are two statements on the internet
  1. calibration is not possible for macbooks that have a glued battery
  2. calibration is possible and you need to let the mb shut down on its own due to low battery charge

To my mind both statements do not apply to my problem since there never is a low battery warning

What I thought about:

• the battery is broken and I have to send it back (I attached an image of cocnutBattery. It indicates that everything is fine with the battery)
  
• my logic board is broken so I have to make sure that I have a charger at hand when I hit the 50% mark
  
• the battery replacement requires some kind of software magic
  
• it is a matter of time and the mb will calibrate itself

I would really appreciate it, if you gave your thoughts on this problem.

Cheers,
Rene