Battery time remaining estimates for computing devices can vary widely in accuracy. The estimates are based on assumptions about future behavior based on prior usage trends, from a mix of current and prior charge usage. Windows updates can disable battery time remaining, and some devices (including Microsoft Surface) may come from the factory with battery time estimates disabled. Even though the battery time remaining estimates on Windows have limited accuracy, I prefer to have the estimate shown.

The usual precautions on modifying the Windows Registry apply–do a Windows System Recovery milestone first. These keys are under:

HKLM\SYSTEM\CurrentControlSet\Control\Power

These settings “worked for me” across multiple models of Microsoft Surface devices and other laptops. Reboot after making these changes.

If these registry keys exist, set their value to 0. If they don’t exist, that’s fine too.

EnergyEstimationDisabled=0
UserBatteryDischargeEstimator=0

Create this DWORD32 value (if not existing) and set to 1

EnergyEstimationEnabled=1

Reference: forum