Looking for advice. I have a Carrera Crossfire e-bike, from Halfords, done 600 miles. Problem is I fully charge it, start riding with all bars on the display showing full, and the battery level showing 99%, then intermittently that changes to two bars and reading 40% left. It then reverts, for a short while to the original reading, but then goes back to the low false reading. Comes and goes like that whilst riding. Not aware of doing anything different.