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. 聽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