The display indicator estimates the amount of battery remaining based on usage. The last 2 bars last twice as long as a single bar and will then go from 2 to 0. Recharge when it reaches two bars to avoid running out of power while riding. Mileage varies based on factors like rider weight, road conditions, and assist level.6 Bars => Full Battery4 Bars => Medium2 Bars => Low Battery, Require Charging.