I have seen this situation two ways.
1. The battery cannot be charged any longer or is not properly connected or the battery is not in the laptop.
2. The charging system is not working properly.
As to the status of the charge on your battery, it is probably going down. Batteries lose their charge over time even if not connected to anything. If the system draws any power off the battery that will just speed up the lose of power. Finally most rechargeable batteries develop a voltage memory which establishes the maximum charge and minimum charge. I recommend taking your putting your battery into your freezer, but if you do be sure you allow the battery to slowly warm (24 hours on just sitting on your desk would be good) after being removed. Attaching the battery to anything including a charger before it has returned to room temperature can easily destroy the battery.