I need help with my battery not charging on Compaq Presario V6000.

My compaq presario i bought on ebay works perfectly except the fact that the battery doesn't get detected, and wont charge,i had bought an ac adapter since this computer didnt come with one. it runs fine on AC and i am using it to type this question. my operating system is windows 7 Home Premium. i have Gone to device manaegr and uninstalled the microsoft ACPI-Compliant control Method Battery and reinstalled it to no avail. Could it be the batter and i am willing to try anything. as long as there is clear directions xD.

This computer was sold with a linux operating system And i removed it and put a windows 7 on it. its OEM system is windows vista. 32bit system.

This computers Charging light flashes (lightning Bolt) While its on.

when i unplug AC sometimes it will stay on but i dont know how much charge is on the BAT so i dont wanna risk an unexpected shutdown.