No battery installed, Shuts down from randnomly.

So i have a macbook air 11” early 2014.

Before i took the battery out i could use it without any problems.

I removed the battery at apple store and at that same time they did the diagnostic test to see if everything is good. Since the battery was removed it did give a error on it. Everything else is good, but now when i use it sometimes it just randomly shuts off or i get logged out, i just need push the power button and log in and everything is still there. I’m sure that the charger is connect. Will buying a new battery solve the problem