How can we keep hot apple cider hot in a black cauldron without starting a huge fire? Just want the effect....?

Every year when i was a kid, our neighbor would put out a cauldron with hot apple cider in it and serve to all of us on Halloween. I am doing an Halloween fundraiser event and would love to do the same as he did. We have a huge black cauldron but would rather not use it due to the heavyness and the fact we would have to stoke the fire all day. Does anyone have any ideas of ways to keep apple cider hot so it can be served in a cauldron? It can be table top, we just want the effect any help would be great. THANK YOU IN ADVANCE!!!