I had the same problem with my Compaq after upgrading to a 12-cell after market white box battery. What I did first was I uninstalled and reinstalled "Microsoft ACPI- Compliant Control Method Battery" and that did not work, so I followed the steps below:
1. close laptop and remove battery (while still on).
2. open lid and remove AC adapter (while still on, will power off system)
3. close lid and connect battery
4. Â open lid, connect AC adapter, and power on.
After I did the above, my system began to charge the battery. Some people say that after step 2, shutdown the system before unplugging the AC. I didn't because most of the solutions I found said NOT to shutdown the system first. If you were careful with your system, this one time shouldn't do any harm to your laptop
Matt102