No, you cannot replace the battery in your Oral-B electric toothbrush. The battery is contained within the electronics of the toothbrush handle and the unit is then sealed to keep it water tight. For these reasons we do not provide replacement batteries for Oral-B electric toothbrushes.
If your Oral-B electric toothbrush stops working, please visit www.service.braun.com where you will find detailed information about the Oral-B warranty and servicing.