Furnace and single battery

So i took it out this weekend and one of you were right, it was doable without the furnace. it dropped into the high 30's at night, however, once bundled up, we slept thought the night with all 3 kids no heater. in the morning, i turned the heater on and got some warmth. So we did not need to run it at night, good thing because it was loud and the smoke alarm went off the first morning from the new furnace being burned the first time, that would of been annoying the first night. The poor battery did not have enough juice to lower the pop up evenly one of the front sides would not go down, i started freaking out, however, once i hooked the generator up and got it going, all went down fine, so it must have been not enough power or the right kind of power