kengr

All I'd need is the inverter from my storage, a deep cycle battery, a case for the battery (just in case it leaks) and a charger for the battery.

Alas, those portable power thingies that can let you start a car with a dead battery, and run 12 volt gizmos don't have enough power as far as I can tell or I'd have bought one years back.

I want 3 days (in case of bad winter outages), plus a safety factor. Call it 12 hours a day. for a total of 36 hours.

The CPAP is about 20 watts. So that's 720 watt-hours. At 12 V, that's 60 amp-hrs. Alas, I think the portable power units are only 20 or so.