Windows 7 - Dell laptop battery problem

I was using laptop today when battery power started dropping at an alarming rate..................I have used the battery 2 or 3 times for less than 10 minutes in 2 years.
Maybe that is the problem.A message said replace battery,when I took the battery out ,it appears to be rechargeable!!??.
The main problem is why did it suddenly lose power?
Hope I've chosen correct place to post. Any help appreciated.

Laptop batteries lose their ability to hold a charge when they are not used on a regular basis. Conditioning the battery once a month will help to recharge the battery and help the cells remember how to hold a full charge. If you let a battery drain slowly due to no use, eventually you will have a dead battery.

Laptop batteries only last 18-24 months to begin with and if it is not being charged and discharged regularly, the cells have no way to learn how to hold a charge. It is very important to initially condition the batttery with 2-4 complete charge/discharge cycles and then maintian it once a month to get the best performance.

More battery tip info:
http://www.batteryfuel.com/faq1.html

Most grateful.So much to learn and I do enjoy that.

maybe your battery is dying, you can replace the battery

i recommend some laptop battery store:
hp laptop batteries
espow batteries