I have also been looking for a good light to drain batteries. I just ran a little test using a Tektite Splashlight LED that I got from Battery Station. This light uses a single CR123 battery.
First, I used my HDS EDC Basic 42 to drain down the battery to its lowest level (.3 lumen if I recall correctly). I then left the unit on for 14 hours until the led began to flash constantly and the light would not stay on in constant mode. Note that the light coming from the EDC was very low and not very useful during the latter half of this 14 hours.
I then removed this battery and installed it in the Splashlight. I was startled at just how much brighter the light was than in the EDC while using the same battery. It was almost as bright as an Infinity Ultra at that point!! (With a new battery, the Splashlight is slightly brighter than the Ultra, at least by my eyes.)
I left the Splashlight on for 6 hours. At this point, it was noticeably dimmer than the Ultra (30-40%??) , but about the same brightness as the Eternalight is when only 1 led is on. The light was still useful and I could easily navigate the house and read writing from a page.
I left the Splashlight on for approximately 4-5 more hours, at which point it would no longer light. The amount of light coming from the Splashlight was dim but still useful all the way up until it would not longer light.
In summary, on a battery that would barely make the EDC blink, I got 10+ hours of useful light from the Splashlight. I normally don't like plastic flashlights, but this one feels good in the hand and seems well made. I got an incredible amount of light from a battery that would not effectively light any of my other CR123 lights. I can highly recommend this light to anyone looking for a small, fairly bright light that can truly drain a battery.