There is no average runtime. Everyone is using different cells and different wattages. If I were to borrow your mod and crank it up to 80W, my runtime would be less than half of yours. Not only would I be using the power at twice the rate, I would also be pushing the limits of the cells you have. When pushing the limits of the cells, you may get more runtime using a cell with a lower mah rating because they will have a higher cdr rating. Sometimes it is better just to think in wattage and watt-hours. General rule of thumb: a VTC5a is good up to about 75w. a HG2 is good to about 60w my best guess would be that your Brillipowers are good to about 30W (remember, just a guess). If you have a 3 cell mod, just multiply by 3. So your mod and batteries are probably good to about 90w. You only have it set at 40w, so you are most likely getting the most of the usable capacity from them. Now if you stuck one of those cells in a single DNA75 and set it at 40w, It would probably fall on its face and give you a weak battery warning way before the battery meter reaches empty because you have exceeded what your single cell if capable of. Escribe has a battery analyzer. It takes some time but not hard to do. Your best bet is to test your cells @40W then compare the watt-hours it calculates to what others are getting.