Looks like you are about right... From a comment of TFA - "Great start, not quite there yet (12/10/08 - 16:41 - by Robert B.) The manufacturer\'s data sheet states 15 minutes output at 270 lumens on high (67 lumen-hrs), or 60 minutes at 90 lumens on low (90 lumen-hrs). From this, I\'d estimate that on low the device draws approximately 1 watt from the ultracap, with each LED each operating at 0.3 watt at around 100 lumens per watt, with roughly 90% DC-DC converter efficiency. This is 1 watt-hour from the ultracap. On high, this device would draw about 4 watts from the ultracap, with a little over 1 watt reaching each LED, given a slightly lower LED efficiency at the higher brightness and a significantly lower converter efficiency, possibly a bit over 75%. Compare this with two AA NiMH cells (at 3 watt-hours each) that together store 6 watt-hours. Ultracaps are a breakthrough technology, but the energy storage density is still pretty low, as we see here. It will be a few years before ultracaps become the most satisfactory overall choice for flashlights."