Ok... maybe I jumped the gun on that last post. After doing some research (God, isn't google great)... I see that most if not all CPAP machines are 12 volt machines even though you plug them into your wall socket (that's how I interpreted it anyhow). So.... if I buy one of the CPAP battery backups, and make sure that is charged throughout the day from my RV battery, I should be able to go many days. Also read where using the humidifier drains the backup battery at least twice as fast. Does all of this garble sound pretty much correct?