What happens when a battery controller loses synchronization with Windows?

You are seeing a mismatch between the battery’s reported percentage or charge state and what Windows displays. Windows shows information it receives through laptop firmware and battery hardware, so the symptom can reflect the battery, controller, firmware, or Windows power management; it cannot prove a controller synchronization failure by itself. Install the manufacturer’s current BIOS or firmware and power-management updates for the exact model. Then shut down, disconnect power, and follow the documented battery reset procedure if one exists; do not open the battery compartment unless documentation permits it. After restarting, observe whether the percentage changes smoothly on battery power and compare the charger status with the system tray reading. Generate a battery report and keep the full-charge-capacity and recent-usage results. If the laptop shuts down well before zero, stops charging, swells, or overheats, stop using it and arrange hardware service. Calibration cannot repair a worn or failing battery.