Are you just wanting to power the refer for a move of 12-24 hours? If so, you do not need to power it at all.
Due to a transfer switch problem, I went over 72 hours without power to the refer. Everything was still frozen and the refer section was still in safe temperature range. Even if a refer is plugged in, the compressor only runs about 10 minutes per hour.
If you have to open the door, think about what you want before and don't just open the door and "surf" the contents