CPAP and BiPAP Power Adapter. The external 90-watt power supply plugs into wall outlets. This is a 90 watt AC supply and it cannot be used in a DC configuration. Additionally, this adapter can be used with all S9 machines. This 90-watt power supply is required for ResMed S9 CPAP Machines using an H5i heated humidifier. Plug Your CPAP In. With the power adapter, you can plug your CPAP machine into wall outlets wherever you go. Don't compromise on convenience: pick up an adapter, and travel with freedom!. Key Features. Charges CPAP Machines. Easy to Use. Travel Friendly. Reviewers Tip. Know what type of CPAP machine you are using. If you are using an S9 machine with a heated humidifier, you have to have a 90-watt power supply. ResMed S9 Series: Compliance Management. FAQ. Does the power cord come with the power supply? Yes, an AC power cord is included. Compatibility. ResMed S9 CPAP Machines.