Protected 18650 in a D4k is an interesting idea, might work, thanks. I will ask Toykeeper if Anduril could notice current limiting in a protected cell. If it a sudden dropout with no voltage sag leading up to it, then it might be difficult. Still, the same question recurs: why not support protected cells in the D4K? The current limit excuse is gone, with the 30 amp protected cells.

I see the space heater mode as similar to the disco lights, basically a party trick. I can do without both. The BC21R works fine on a protected cell and has a heater mode advertised at 1000 lumens. Bathroom comparison with the D4v2 says the D4v2 is brighter by maybe a half stop, but i have to compare carefully to notice the difference. Both are too bright (they wash out my vision) for close range use anyway, and they heat up too fast for steady outdoor use. A momentary turbo mode can be handy for outdoor distance spotting, but a D4v2 with 219a’s and flood optics is the wrong light for that anyway. If I want a thrower I’ll buy one for the purpose.

I do realize there is not much differentiation between BLF lights, so buyers look at the lumen spec and pick the biggest number, but some of us are more discerning ;). Anyway, Hank offers all those hardware options, so it seems like a simple matter for him that if you order a D4v2 with a 70mm tube, it can be set to lock out current draw above whatever. That should just be a software setting. I think it was Bill Gates who said 640 lumens should be enough for anyone (oh wait). Didn’t you tell me that you yourself don’t use the max level of the d4v2 for lighting? My D4v2 does (eyeball guess from BC21R comparison) around 1400, so if it becomes 1000 or a bit lower with a battery swap, I can live with that. I’m pretty sure it dims a little as the battery depletes anyway. I did the bathroom test with a just-charged cell.

I’m having trouble believing the linear driver pulls anything like 18 amps from the battery. That is 60+ watts, 15+ watts per led, and they are not rated for that. I may try some tailcap measurements. It is certainly a waste of battery power, since the leds are way less efficient at such levels. It solves an imaginary problem.

My brightest light really is a 3D incandescent maglight (the notorious Ultimate Stealth Light from CPF). It uses a handmade high current nicad pack and a 100 watt slide projector bulb for around 3000 lumens. You can feel the air around it get warmer when you turn it on. I never use it though.

I don’t see what the DT8K has to do with this. I don’t particularly want a DT8K.