Compaq HP 6715s Laptop not charging!

If you can determine that it is not the battery just going bad, then most likely it is a problem with the motherboard. I actually have this same problem, and have not been able to find a quick fix.

HP has a battery tester tool. If you are able to use this, then you are one step ahead of where my HP laptop is. I tried running this and it insisted that I did not have a battery installed, or that it was dead. If you have this same problem, then it looks like it might be time for a new motherboard.

In anycase, it might also be worth the time to try draining the battery completely and attempting to charge it back up. According to a few other sources, the laptop can sometimes get confused and think that a full battery is calibrated to be a low battery.