From HP support:
Resolving "Battery Not Detected" Problems
Sometimes Windows does not detect the presence of a battery. This can occur even if you have a good battery. There are several things you can do to resolve this problem. HP recommends doing each of the following steps, in order, and then testing to determine if the battery is detected after performing each step.
You can test for the battery while the AC power is connected and when the computer is running on battery-only power.
Perform a hard reset.
Reset the BIOS defaults.
Update the BIOS.
Determine if the notebook starts using battery only.
Did hard reset: No change
Bios is very basic, no option to reset defaults
Bios is latest version
Notebook starts on battery only
In essence, laptop works on battery, but will not recognize battery even when diagnostics program is run, returns "No battery detected". Removed and replaced batters driver in device manager. No change.