S9 with Escape 150 power pack

[Treehorn]

Another user I know recommended that I use a Goal Zero Escape 150 power pack with my cPap when camping.

http://www.goalzero.com/p/16/Escape-150-Power-Pack
It claims to have a capacity of 150 Wh, 14,000mAh

I suspect the device they shipped me is defective because I can only get 1-2 h use out if it.
I am using my S9 without the humidifier and with EPR turned off.
I have the brick that is designed to power the humidifier when at home (90 watt?).

Before I call the manufacturer of the battery about warranty I wanted to make sure that I have my facts straight.

From what I can tell the S9 documentation it should use 12 amp-hours (12,000mAh) over 8 hours and that is with a 50% safety margin.

My fully charged 14,000 mAh battery should do the job. I would be happy to get 6 hours or so but 1 to 2 hours is horrible.

Am I missing something in my numbers?

Thanks,
Andrew