I've had this sonicare rechargeable toothbrush for several years now and it works great. It recharges the battery when sitting upright in it's cradle and both the cradle and tooth brush are sealed in plastic with no metal contacts. When recharging both get warm. I have always wondered how it could recharge with no metal contacts. Any one know how this works? I was hoping it would break someday so I can take it apart to look but it's kinda expensive so I can wait for now.