battery not charging, won't run off battery
battery not charging. Macbook air shuts off as soon as charger is disconnected
MacBook Air
Try an SMC reset.
Run the Apple Diagnostics.
Option click the battery icon on the menubar. Any condition except "Normal" or "Good" indicates the battery needs to be replaced. If the battery icon has an "X" on it, then the battery is not seen and needs to be replaced (it could also indicate a Logic Board issue).
If the battery passes the Apple Diagnostics and the condition is "Normal" or "Good", then there must be a hardware issue with the charging circuitry which will need to be repaired by Apple or an Apple Authorized Service Provider.