I'm re-posting this here from liquidretro's review thread:
I just tested the HD20 I got yesterday from Amazon (Prime 2 days) on a freshly charged 40T and on turbo got as high as 6.6 amp tail readings on just the spot LED. Amps crept up the more I compressed down on the spring, using a clamp meter with the tail off. The battery fits very tight, so good spring compression on both ends.
My maukka calibrated readings was about 1470 lumens at 30 secs on just the spot LED (XPL HD) both LED's, tailcap on. Initially, the reading actually goes up a little, then didn't drop much at all. This is all indicative of the springs combined with a direct FET driver. I've seen this type of variation a few times before. It's also clearly in the ballpark for 6.6 amps, and the light got quite hot to hold in 30 seconds. So the amps readings, heat, and lumens reading all correspond.
Dunno, maybe I got a new version, or a buggy one, if everyone else got much lower readings on a 40T cell.
My mistake - the bug got me! Dbl clicked ON with prior selecting only the hot spot LED, and the flood LED turned on too, and I didn't notice.