3 ms·
That's marketing hype. From the CREE datasheet at https://cree-led.com/media/documents/ds-XHP702.pdf https://cree-led.com/media/documents/ds-XHP702.pdf, each LE
by Blammar 5y ago
That's marketing hype. From the CREE datasheet at https://cree-led.com/media/documents/ds-XHP702.pdf https://cree-led.com/media/documents/ds-XHP702.pdf, each LED runs between 1500 to 2000 lumens.
That flashlight has 18 LEDs, so 36k lumens at the most.
Also, for the rated brightness, each LED has to be run at 12VDC 2.4 amps or ~30 watts. The thing has 8 21700 cells at ~3.7v each 4Ah. So the cells are probably wired in a 2x4 configuration giving 7.5v and a total of 32Ah. Current draw for the LEDs is higher at lower voltage, so it's 12/7.5*2.4A = ~3.8A per LED or ~70 amps total draw. So yeah the numbers show it's feasible to run the 18 cells at full current for about 25 minutes and get the 36k lumens.
The heat dissipation will be about half a kilowatt, so quite likely the flashlight will get too hot to hold fairly quickly, even with its heat-pipe cooling.
I'm not an EE, I'm just channeling my long ago physics class on circuitry, so I could be egregiously wrong in places.
- jaggederest 5y agoThey usually run them through power regulation circuitry (a boost converter or the digital equivalent) and overdrive the LEDs, maybe into the 24v+ range. The "turbo" mode usually only runs for a few seconds at most, and is where they derive the high lumen numbers from. With this kind of flashlight you have to use unprotected lithium ion cells because they far exceed what the protection circuitry will let you do. Also related to their tendency to go kaboom if set up wrong.