This is interesting. My older Macbook Air 13" (mid 2012 model) has had a 3rd party battery in it for a while and the charging has always worked fine. Even after applying the original El Capitan upgrade, it still charged fine. Just this morning, I applied the latest El Capitan update and now it claims my system doesn't have a battery! I have changed nothing other than rebooting and applying the latest update. My guess is that Apple has applied some MacOS changes which now recognize non-apple batteries and stop your system from using them! (I have now purchased a real Apple battery from an ebay seller, with a 90 day warrantee. We'll see if that fixes it.) Just thought I'd send a warning out there!