ups sine wave

[powertrip]

why not ups sine wave and cpap? why only battery?

[Julie]

Could you elaborate just a tad please on your note?

[idamtnboy]

why not ups sine wave and cpap? why only battery?

Capacity, plain and simple. A regular computer UPS will work, for maybe an hour or two, unless it is a really huge one. The batteries we discuss and recommend will power a CPAP from one full night to 4 full nights.

[archangle]

Sine wave inverters are usually rather inefficient, especially at low load levels. Even a modified sine wave inverter is inefficient, just not as inefficient as a sine wave. The CPAP machines run off DC. If you can avoid converting the power to AC then back to DC, the battery lasts longer.

ResMed S9 and PRS1 machines work fine off of modified sine wave inverters, so there's no need of the extra inefficiency of a "pure" sine wave inverter.

As idamtnboy said, most UPS's won't power a CPAP for very long. However, they do work great for the time they're running.

[-tim]

I don't think the S9 power supply would care about the input from the worst inverter/UPS/generator you can find. I have inverters that are close to 98% efficient but many are closer to 50% at the loads of a S9 without the humidifier or heater on.

Too bad the S9 needs a signal from the power supply to use 24V or else a 24V deep cycle battery and a charger is all we would need.

[CapnLoki]

... I have inverters that are close to 98% efficient...

Could you supply model or specs for your 98% inverter? I've been on a quest for a high efficiency consumer priced unit, especially low power, like under 50 watts where most units are about 65-75% efficient or worse.

Too bad the S9 needs a signal from the power supply to use 24V or else a 24V deep cycle battery and a charger is all we would need.

True, but the 12/24 volt converter is not a bad solution for S9 users.