Troubleshooting guide
How to fix the problem
"AC adapter unknown" means that Dell does not recognize the type or power of the charger. The computer can turn on, but not charging the battery and limiting the speed of the processor. Check power first, not reinstall Windows.
Possible solutions
Choose the method that matches your situation. Start with the simplest suitable option and check the result. If the problem is fixed, you do not need to continue with the other methods.
BIOS inspection
Check what the computer itself sees about the charger.
Steps to follow
- Turn off the computer and plug the charger directly into a power outlet without the dock.
- Press F2 several times while powering up. Dell BIOS search for Battery Information or AC Adapter; the location of the section depends on the model.
- Note whether the specific wattage is specified or Unknown / None. Compare with charger label and model requirements.
- Exit without saving changes. If power is not recognized, proceed to the next appropriate charger test.
Testing for a suitable charger
Isolate the fault of the charger, the cable and the computer socket.
Steps to follow
- Inspect the cord and plug of the unplugged charger. Do not use a charger that is damaged, sparking, or abnormally hot.
- Try a Dell charger that is specific to your model. USB-C models require sufficient USB Power Delivery power and a suitable cable.
- Check the AC Adapter again in the BIOS window. If another charger is recognized, repair or replace the first charger or its replacement cable.
- If no suitable charger is recognized, complete the tests and send the computer for socket and board diagnostics.
If the problem persists
If the BIOS does not recognize a suitable charger working on another computer, a check of the power socket and the identification circuit is required. Write down the status of the charger displayed by BIOS and its power. Do not disable temperature or power protections.
Request a repair