First question: do you get a window pop out saying to plugin it in?
If you do - it means that your cord is problematic and is not supplying power properly (I'm having this problem right now);
Second question: when you have the cord plugged in without problems does it load the battery or the battery is never getting loaded fully?
If the battery is not getting loaded - it might mean that it cannot do so. Several reasons - it might be dead, the cord might be problematic, the little... (I don't know the word in English) hole where the plug is going, might not be making good contact, and so on.
Is your laptop working properly without a battery and only with the plug?