I have a question about my Xbox controller?

I just spent the night at my brother's house. He lives in Oakland, and I live in Modesto. We tried to play 2 players on Resident Evil 5 and MW2, but my controller wouldn't work when I tried to turn it on. The center would just flash green. He hooked his battery charger up to my controller, and it worked when I turned it on. Now that I'm home, my controller wont sync with my Xbox, just like it did his, before he hooked the battery charger up to it. Will I have to buy a battery charger to hook up to my controller for it to re-sync with my Xbox now? Because I really don't want to have to buy something thats $20 when I can live without it. Thanks.