Because it’s severely underdriving the LEDs. At 7 LEDs you would like to see 14 amps or more, 2A per LED, hell, even 10.5 for 1.5A per LED would be better, but at 7.5 for 7 LEDs you’re giving each just a little over an amp, almost pointless.
Oh yeah, I missed that, thanks. I thought the 7.5 A was battery current but I see now that it's "regulated" 7.5 A so it must be the LED current. Gee, if that 7.5 A figure is true, it's only pushing about 25 W into the LEDs. Some of the 3x XM-L lights are doing 30 W or more already, so what would be the point in manufacturing this huge light driven at only 25 W?
I hope the 7.5 is a typo. Or, if the 7.5 A turns out to be the battery current, now we're talking...
7.5 A x 4 x 3.5 V (approx. battery voltage under load) = 105 W
driver efficiency = 80% approx. ==> 84 W reaching LEDs.
12 W per LED ==> about 3.5 A per LED. That would be awesome but the light would get stinkin' hot, fast.
We need 9 XM-L heads now. Then we can stuff 3 x DRY drivers inside and use 3 x 26650 IMRs or King kongs. Hehe.... In High it should do approx 5000 lumens OTF? (IIRC it is about 1700L OTF in High with fresh cells). Turbo, if the batteries can take it then 7500L OTF is doable.
4A x 12.6V = 50.4 W pulled from cells
50.4W x .80efficiency(typ) = 40.32W into LED array
40.32W / 7LED = 5.76W/LED
5.76W / 3.4Vf = 1.69A per XML (assuming 3.4Vf)
So on paper it should be more lumens than the TR-J18/J12, and the bigger reflectors will project a tighter beam. It draws almost double the power of the TR-J12.
After the accident, realised that life is short. need to get more lights.
2.3-2.4A seems to be near the original triple XM-L SR3800….but that’s like 2.55A 2 cells but for 3 XM-L. This is with 1 extra XM-L for slightly better efficiency. I think this one could be like ~ 3200 lumens OTF. Cool!