When does the GREEN charging light go out on my Philips headphones?

It is not an indication that your batteries are fully charged. It simply states the 16 hours charging period has ended. The green charging light will go out after the 16 hour automatic charging process has finished. Note: * Each time you remove the headphone from the base unit and re-install it again, the automatic 16hrs charging process is activated again. Thus the green light will also be active again. This is normal and does not affect your batteries. * During the charging process the headphone must be switched off