Though I had 100% charge on my battery, my Macbook Air 2013 won’t turn on without connection to the power adapter. It would turn off when unplugged. I did as suggested - PRAM reset and SMC resets but the problem persisted. Figured I had to buy a new battery, even when running a Apple Diagnostis said my device has no problems. I decide to practice removing the old batteries and putting them back so I know what to do when the new batteries came. Interestingly, disconnecting the battery from the logic board and reconnecting solved the problem of needing a power adapter to run. My unit now works pretty well….