Macbook Pro shuts down at around 50% battery

I have a mid 2012 13 Macbook Pro. I had changed the battery with an after market battery and it works, however, it doesn't last as long as the original one. Recently I did an SMC reset due to another problem, and now my battery percentage is not shown correctly. When fully charged it stays at 100% for a lon time, and at around 50% it shuts down abruptly. When I turn it back on battery is shown at 0%. So far I tried resetting the SMC again. I tried draining the battery and recharging to 100% two times, but the problem is the same. Here are the results of my last discharge: 11:30 100% 11:53 96%

Question by Tolga Inci on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.