Dell Power Manager Lite, Windows 10 Home, plugged in but not charging

I have a Dell Inspiron 15 (i7548-2129SLV). The system worked fine for a couple of years. Now, on boot, I get the message: 
"The AC power adapter wattage and type cannot be determined. The battery may not charge. …"

But I have a Dell 65w power adapter and it is connecting properly (the screen is brighter when the power adapter is connected). BIOS shows the battery is in excellent condition, as does Dell Power Manager Lite. Battery icon in the task bar shows “16% available (plugged in, not charging)”. I have followed all the instructions in another thread with the same subject, including uninstalling and reinstalling the ACPI-Compliant Control Method Battery in Device Manager, and the problem remains. I even bought a new power adapter, but same problem.