try plugging one battery into just the right port with nothing in the left and see if it will charge the battery in that port alone.

Let it charge in the right side for a sufficient amount of time and see if you can use the battery with the Xbox. BTW, I've always been curious, why would one want/need a play-n-charge kit? Why can't you just plug it in? Even if it's for use on a long road trip in a car, there are AC inverters that would work much better IMO.

Well, I returned it and exchanged it for another new one. Go figure.... the new one works, but is kind of wonky. The rechargeable battery that comes with it charges on one side, but not the other. The thing is, the older rechargeable I have works on the side that the newer one doesn't. Friggin.... ah well. They do charge correctly, though.

I could plug it into the xbox via the usb ports or any usb hub for that matter, but when I got my black battery and charging cable combo (used) from gamestop, I noticed that the cable was slightly cut at one point. It's worked for a while, but it needed to be in a very specific position to charge the battery while it was in the controller. So I just decided that I'd get a charging station that came with another battery anyway and be able to have one ready to go at all times. Plus, what with a very... energetic dog running around inside every night, it's just one less thing for it to trip on, pull or damage.