For a P2 binned LED at 1250 lumens, without counting optical losses, you get 200 lumens/W from Texas Ace’s test. 175lm/W is a pretty conservative number if not counting driver losses if we have a 90% efficient reflector, then a 98% efficient lens.
I don’t know where you got your 111lm/W at 1250 lumens, especially knowing that in his own test, at 4,8A,/6V, the XHP70.2 does 130lm/W.
The LED can’t be less efficient at lower power levels, no?
I was not using Texas_Ace’s 70.2 chart as that test was made before he calibrated his Lumen Tube. So his output numbers are a bit too high.
I was also using 8v to factor the wattage. I was thinking 8.4v batteries would have minimal voltage sag at these lower currents. I believe his led tests are done from a power supply so it would be set to constant current mode meaning the psu voltage varies based on the amperage. (I wonder if FET based drivers vary the voltage, as well as control the amperage, through PWM? Anyway…)
If we use TA’s bare led lumen 85°C and voltage numbers:
1.4A x 5.7v = 8 watts. 1250 lm ÷ 8 = 156lm/watt.
Efficiency does get worse as the amps increase. We always see the lumens climb with amperage until it reaches the top of the “hill”. That’s when the heat starts overiding the lumens and the output starts dropping.
To bad the original Q8 extension tube is not happening. Now that the 3V XHP50 is out Led4Power will sell much more of his Q8 ledboards. Would have been nice to get the runtime upgrade with the tube extension!
No heavy modding needed. Change of leds (wires + springs) and add the tube.
10000+ lumen for short times with usable runtime (on lower levels).
Ok this one i forgot. But it is not rocket sience. Yeah you could ruin the reflector if you are having two left hands but i think most people that are capable of soldering are also capable of opening the reflector from 4 to 5mm.
The end result would be a light with ~ 3x the output of a unmodified Q8.
It will get hot very fast thats a fact. But imagin a Q8 with extension tube capable of 10000-15000 lumen on turbo.And many many hours of runtime on low and mid mode.
This led combination could revive the Q8 modding a lot.
I think the light was not modded “so often” because it was to good from the start.
Sure you could get a better CRI value going with different leds. And you could gain a few %. But there was nothing out there that would give you 2-3x the output without doing some heavy modding.
Now it is easier than ever before.
A nice option would be a upgrade set out of presolderd ledboard (with 3V XHP50), Blue Springs, maybe a new optimized reflector (orange peel) with centering rings and the extension tube.
But i am dreaming again
Can we get an update from Sofirn about whether the tubes will be made or not? There are already the Q8 and the LT1 (hopefully) that can use extensions. The Lantern already makes sense to use extensions to get more runtime. The Q8 is okay in stock form, but mods like changing to a 3V XHP emitter will make it more of a candidate for extensions. Some of us have already wanted extensions for some time.
Thanks for the update, Barry. Looking forward to some impressive runtimes with 8 batteries when they’re ready. I was in for just a set for the BLF Q8 but I’ve now got a Sofirn Q8 in the mail so will end up getting 1 set for each Q8 (2 sets total).
Nice to hear that the extension tubes are still going to come out! Lantern tubes would be necessary if you go on a camping trip where you can’t recharge the batteries and therefore need 8 or 12 or 16 18650 . I don’t mind waiting as long as they come out at least this year. You mean the machines are busy with the SP70 or other unknown lights? Alright, then go on producing!
In that use of taking extra batteries, it could be nice if the extension tubes come with a screw-on cap on the top side. Preferably plastic btw because it must keep the batteries insulated from the tube.