Same problem here (drop from 70% to 7%) after following these instructions: https://help.ifixit.com/article/265-battery-calibration I also did the SMC reset. I am getting about 3hrs of battery life with just the activity monitor and with the screen on (66% of brightness) I did have a similar problem two years ago with another ifixit battery I bought for a MBP 2011 13”, I sent it back and bought a Newer Tech battery that also reports an inaccurate percentage. I am really frustrated with this after spending 80€ on a battery that is supposed to be of high quality.
