First thing to try would be a new, OEM Dell AC adapter.  Match the capacity to the one you now have: [URL] If that doesn't solve the problem, it doesn't appear this system has a replaceable DC jack, so it'll mean replacing the main system board.      
"Alert! The AC power adapter wattage and type cannot be determined. The battery may not charge. The system will adjust the performance to match the power available.” Is the message I get when I turn on my computer.  This appears to be a laptop issue, but I have a Dell Desktop All in One. Inspiron 7700.
Adapter error