No doubt on that, A Jackery 240 has 4x the battery capacity of my jump battery (20.8A@3.7v rating - 74Whr). I wouldn't expect it to run too long, but if it could do 6-8hr in the shade, especially if it was brought to temp on shore/alternator power, that would work. I need to get a better battery setup. I just had this lying around.My guess is that it has a really low battery capacity, with it being a jump pack. They are more designed for boosting and not for sustaining.
When I ran it out of the Jackery 240 I was able to get it to last 8 hours in the sun and about 20 hours in the shade. Even if you are in the middle of the desert and it has to stay on full time (compressor), the most it should ever use is 50-60 watts (DC lower). A jackery 240 wh (smallest bank from them) will still last 4-5 hours.