Rechargeable batteries for the xbox360 controllers are a must. Saves you money so you're not always buying new batteries. But just like rechargeable batteries are a must, EXTRA rechargeable batteries are a MUST HAVE. if one of your batteries starts getting hot while its charging or dies instantly when you turn on the controller, then its time to replace that battery with a new one.
i bought these for my dad's controllers, once i convinced him to buy his own xbox and stop using mine. they work great and keep a charge for a long time.