Batteries and Power

[wiseyoungowl]

While upgrading to Windows 7, something went wrong and one of the things I noticed was that the battery was no longer being detected.  I eventually reinstalled Vista from the CD's that came with the laptop, but the "battery not detected" message is still there.  I have now successfully installed Windows 7, and still the same.  The computer seems to work if it is on and I unplug AC, but will not start from battery.  Any ideas how to solve this problem?