Follow this link for the manual: http://download.p4c.philips.com/files/s/sbchc8410_34/sbchc8410_34_dfu_eng.pdf
This is from page 7 of the manual:Headphone battery replacementIMPORTANT
Use only rechargeable LR03/AAA NiMH batteries (preferably Philips).
Do not use NiCd batteries or alkaline batteries as these may damage
your FM wireless system!
1 Remove the earcushions.
2 Take out the batteries and dispose of them
3 Insert new batteries. Only use LR03/AAA
NiMH batteries (preferably Philips).
4 Make sure the batteries are correctly
inserted as indicated by the engraved
symbols in the battery compartment.
5 Put the earcushions back on the earshells.IMPORTANT
Before using the FM headphone for the
first time, please ensure that the
batteries are fully charged for about
16 hours.This will guarantee a longer
operating lifetime of the batteries.
Good luck, please post back to this solution if you have any difficulties, and thanks for using FixYa.