Macbook Air Early-2015 Service Recommended Warning
Have you contacted Apple to get a quote on the battery? They can run diagnostics remotely and send a box. It’s worth the time in case they want to service the battery due to a service program at no cost to you. Once they ask for service, it could be a short time till it stops working entirely. Or you could run on wall power at slower speeds until you want to replace or repair it.