@manton Try one of OWC battery calibration videos (macsales) they have for battery replacement for your model. My older Macbook air would "discharge" within an hour and during charge, flatline for about two hours before reaching 100 percent. It also shut itself down during closed lid sleep in two days. Did the calibration routine and after staying at 4 percent for four hours, it shutdown. After full calibration, battery performed much better. Sleeps fine. YMMV