Can weak battery = power to jack but not cabin?

Just went over to storage to get the trailer ready to be unearthed and brought to the house for the summer. I hooked up the battery (which has not been charged) and the power jack operated. There was no power, however, to the trailer itself. Is this just a reflection of a weak charge? Does it need to be better charged to operate through the converter? Or, is this indicative of something else?

I'll be able to plugin and better charge tomorrow, but I wasn't sure about this and thought I'd reach out here for some insight. Thanks!