I have a very similar model (-P344) and first make sure the charger is putting out at least 19vdc. They have been known to fail.
Second download a file called BatteryInfoView from Nirsoft and when plugged in see what it says particulary the charging voltage (my R3 shows 17.450), battery capacity (mine is around 31,000 mWh), current capacity, charge/discharge rate, and power state.
This is now my preferred travel unit though has been hotrodded with 8GB memory and an SSD. It is a lot faster than it looks.