Why does my nexus 5 shuts down randomly?

[AC Question]

My nexus 5 when gets to around 70 percent of battery, and I do something, it just shuts down. After that it says that there's no battery. This never happens when it's charging. What should I do?

 

[B. Diddy]

Welcome to Android Central! The battery might be starting to fail. Or there might be a bad connection somewhere. Less likely is a 3rd party app causing instability--you can rule that out by booting into Safe Mode and seeing if the problem persists: https://support.google.com/nexus/answer/2852139?hl=en