I have repaired many macbooks with the same or similar problems. Sometimes the macbook wont recognize the battery.
Here are some things I have done to fix theses problems on some macbooks:
* Disconnect removable devices from the macbook such as USB drives, firewire drives etc.
* Remove any discs from the superdrive.
* Disconnect the charger.
* Remove the battery.
* Press and hold the power button for 10 seconds.
* Connect the charger while still holding the power button, keep holding the power button for 10 seconds. (Note: This must be done WITHOUT THE BATTERY)
* Turn the macbook on and immediately press and hold command+option+P+R keys. Release the keys when you hear the apple chime sound 3 or 4 times. (must be done before you see the white screen at start up)
* Shut off the macbook when you get to the login screen or the desktop.
* While the macbook is OFF press and hold Command+Option+Left Shift+ Power Button for 5 seconds. The sleep LED will go crazy and you might hear a loud tone coming from the speakers. Press the power button one more time to restart the macbook.
* Again shut off the computer and remove the charger.
* Install the battery and try to turn on the macbook.
* Check to see if the battery will charge now and if the macbook will recognize the battery.
If doing all these things does not work then there is one more thing that you can do that has worked for me in the past BUT I AM WARNING YOU, IT IS DANGEROUS SO TRY AT YOUR OWN RISK.
* Remove the charger.
* Remove the battery.
* Press and hold the power button for 10 seconds.
* While still holding the power button connect the charger.
* While still holding the power button and the charger is plugged in connect the battery.
* If the LED on the magsafe turns bright green then the problem is solved and the macbook is recognizing the battery again.
I hope this helps, good luck!!