Check the obvious first
- Try a different wall outlet and power strip.
- Inspect the DC jack and charger cable for damage or loose fit.
- Check the charger brick — it should be warm after a few minutes. If stone cold, the charger is dead.
Reinstall battery driver
Device Manager → Batteries → right-click "Microsoft ACPI-Compliant Control Method Battery" → Uninstall device. Reboot. Windows reinstalls the driver automatically.
Reset the EC (Embedded Controller)
Shut down. Remove the charger and battery (if removable). Hold the power button for 30 seconds. Reconnect and power on.
BIOS battery mode
Some Lenovo and Dell laptops have a battery conservation mode in BIOS or a companion app that caps charge at 80%. Check Lenovo Vantage, Dell Power Manager, or ASUS Battery Care.
Hardware failure
If a new charger does not fix it, the DC jack or charging circuit on the motherboard may need soldering repair or board replacement.