Battery problem + where to get replacement

xv24bb

Hi all.

Couple of days ago I ran into some strange behavior of the phone. As soon as the battery level drops to about 60%, the phone gets "unstable", e.g. freezes or restarts when I try to open an app, unlock the phone, or even touch the screen when unlocking, turning the phone unusable.
The problem stops when I plug the power cord and does not show when the battery is well charged (>60%). Obviously the battery is broken in a way.  

1. Can any of you confirm similar behavior?

2. Do you know an app to diagnose, measure and log some battery data ?

3. Where can I get replacement battery to use the phone in the time I return the faulty battery to the seller?


Thnk you for the help.