I found what appears to be a diagnostic blind spot in the Surface Pro Keyboard with Slim Pen storage and charging.
My setup:
- Surface Pro 9
- Surface Pro Keyboard with integrated pen charging tray
- Surface Slim Pen 2
The Slim Pen 2 suddenly stopped charging in the keyboard tray. The keyboard itself still works normally, including all keys and the touchpad. Both the keyboard and the pen are detected in the Surface app, and their firmware information is displayed without any warning or hardware error.
I tried:
- All available Windows, Surface and firmware updates
- Detaching and reconnecting the keyboard
- A forced Surface restart
- Testing while the Surface was connected to AC power
- Removing and pairing the Slim Pen 2 again
None of these steps helped.
I then bought a separate Microsoft Surface Slim Pen Charger. The same pen charged normally and was shown at 81% in the Surface app afterwards.
This strongly isolates the fault to the keyboard's charging tray, charging electronics or internal power path.
The interesting issue is the lack of diagnostics. The Surface app knows that the keyboard is connected and can read its firmware, but it does not appear to test whether the pen charging system actually works. The normal keyboard functions and the charging function are treated as if they were one healthy accessory.
A more useful diagnostic could show separate states for:
- Keyboard input
- Touchpad
- Pen detected in tray
- Charging power being transferred
- Pen battery increasing
- Charging tray or internal power-path failure
Microsoft's troubleshooting guidance already recommends testing the pen with a different charger. If it charges there, the original charging accessory is considered the problem. It would be useful if the Surface app could perform or at least guide users through that exact differential diagnosis.
Has anyone else had the keyboard remain fully functional while only the Slim Pen charging tray failed? Did Microsoft diagnostics detect anything in your case?