Here we go again, another laptop that doesn't hold a charge. This is another common problem today, please read below.
"My laptop is only a year old. It needs to constantly be on AC power, even when I charge it, the moment it is taken off AC power, it displays the LOW BATTERY icon and asks to immediately be switched to a power source. The charger adapter box has a green light (shows its working?). I've even tried charging it the whole night but it still says LOW BATTERY when I take it off its charger.Please help, thank you!"
It's one of two things, the more likely of the two is that that battery is totally shot, laptop battery's are usually only good for 1.5 years then loose there ability to retain a charge. It sounds like that one's just done. Unfortunately that those batteries cost more than there worth, 100 bucks or more. The second possibility is the power cord, is that the original power cord for that? Or was on that was bought aftermarket, some aftermarket chargers will only power your laptop and not charge. Also remove the battery and check for corrosion. You can build your own battery for a laptop if got a few hours time, and are good with a soldering gun. You get the lithium ion cells you need for about 40 bucks.Follow the below link for a step by step on how to build your own battery http://www.metacafe.com/watch/479447/laptop_battery_hack_youll_save/