The optional internal backup battery protects the ventilator from low, or failure of, AC power. If AC power fails, the ventilator automatically switches to operation on backup battery with no interruption in ventilation. The battery powers the ventilator until AC power is again adequate or until the battery is depleted. The 4.4-V, 11.5-Ah lithium-ion battery has a run-time of at least six hours under normal conditions.
PLEASE NOTE: This repair guide was developed by the iFixit team based on Philips's own service manual. Neither iFixit nor this repair guide is endorsed by or affiliated with Philips.
Replacing the battery is discussed in:
* chapter 5-4 “Preparing for ventilation - About the optional backup battery” of user manual
* appendix A-3 “First-time installation - Installing the optional battery” of user manual
* chapter 7.3 “Component Removal/Installation - Internal Battery” of service manual