VXE R1 PRO Battery Report Issue

Hi, I've been using a VXE R1 Pro for 4 months and the software seems to always report the wrong battery percentage, the battery goes from 100% to 30% in 5 days but the last 30% lasts another 5 days until 15% is reached, and after this (normally) i charge the mouse. I didn't charge the mouse this time and im going to the third day with the battery in 15%. I dont now if you guys can understand but i could find a solution to this, if someone has this issue or know why its happening would be very helpful.