How can I keep my MBP's battery from charging without removing it?

My battery has expanded and has to be replaced, but I am currently writing my thesis and intend to only keep using my MBP for a few more weeks before I buy a new one. I have heard that it is dangerous to charge the battery once it is in an expanded condition, but I cannot remove the battery myself. Is there a way I can use my Mac with the A/C chord without charging (and without using) the battery?