Mine has a special battery pack, it's not just rechargeables in there. I'm sure it also says somewhere in the instructions not to use normal or rechargeable batteries but I'm at work so cannot check for you.
I may be wrong so worth doing a search but i'm sure i read on these very forums that some one opened a battery and it had rechargable batteries inside! Nothing special at all. People have even replaced with longer lasting rechargable batteries.
i got the charger and 2 official batteries, now when one is running low i just change it for the other one and set the run down one to charge.
ive also got the play and charge but havent used it, i only got it for the battery u get with it.
whats the point in having wireless controllers then plugging it back in again?