Jay,I have done overnighters on my 22" using the DIGIQ II and the fuel tends to run out after about 18 hours, but I am still able to keep her at 225* until I hit the 18 hour mark. There is just too much area to bring up to and maintain at the desired heat temps (only heat to 225*) to go much past that amount of time. Still love cooking on it though. The 18" that I had I was able to maintain 225* for 27 hours, but rarely needed that many hours to finish a cook.