Got a silver T3 and decided to put a SST20 DR in it, along with Convoy’s dual-chemistry driver.
Modes and Currents
Convoy claims that the drive currents on AA are 50mA, 350mA, and 1700mA (presumably current at the battery, not emitter), without specifying relative brightness. The relative brightness I observed are 2%, 23%, and 100%. The 2% is usefully dim, more so than “0.1%” modes from Convoy’s buck drivers for white light.
The UI is not the usual 12-group but just the single group above, with mode memory. I would really prefer the mode memory to be removed, since red lights are for night vision preservation and should therefore always default to the lowest mode. The 12 group UI is excellent, and I don’t know why it is not implemented here.
Runtime Graph
Here’s a runtime graph with a new white eneloop AA 2000mAh. The blip near the beginning was me messing with it and not produced by the light.
A few things can be immediately observed:
- The driver is unregulated, despite being a boost driver! The proportional spacing between modes remains the same as battery depletes, which suggests that even the lower modes are unregulated. Fortunately, the NiMH chemistry has a stable enough voltage vs capacity curve that this is not a huge issue.
- Although there is an initial sag, I’m inclined to believe that it is voltage sag at the battery and not thermal in nature. The light barely gets warm 5 minutes in, and remained at most lukewarm throughout the entire test. On the other hand, the red emission is easily registered on skin as heat, so the drive power must have been decently high. This is not surprising, given the extreme efficiency of the SST20 DR emitter compared to white LEDs.
Redness
The light itself is quite charming, noticeably redder than most red LEDs. Not quite as a red as a 650nm laser, however, due to the heavy left tail of the spectrum that bleeds into orange-red, which is perceived more strongly by the eye than the true dominant wavelength.
While it’s hard to test/quantify how much it helps dark-adapted vision, I do notice that red light brings out the outlines of most objects much, much more clearly compared to white light of equal or greater intensity. I suspect this has something to do with the long wavelength being less affected by refraction in the eye. Ever tried to focus on a pinpoint blue light in the distance and noticed that you can’t see it as a pinpoint no matter how hard you try to focus? Red light does the opposite.
Overall I’m quite happy with this emitter+driver combo, especially for the price. I still wish the driver had 12-group though!