URL for the battery pack? How do you intend to charge it? Airsense10 without the humidifier uses about 1AH/hour at a setting of 12.5 according to one post I read. You will get either significantly less power usage with a lower pressure and significantly more power usage with a higher pressure.
Try searching on
http://www.cpaptalk.com/CPAP-Sleep-Apnea-Forum.html, lots of battery discussions.