On lights that use a boost or buck converter the voltage drop under load decrease the total power availiable, so high drain cells gain some Wh over low drain cells
Lets say the LED and driver need 30W on turbo
A 18650GA cell gets like 0.15V less drop over a protected low drain cell like 18650B
So 0.15Vx(14Ah)+3.6Vx0.4Ah=3.54Wh more energy
So 7 minutes more runtime
I just got my BK-FA09s this morning. I tested it for lumens against the K70 and got 2565 lumens for K70 and 2520 for FA09s. The reflector dimensions appear the same between the two. The K70 head is wider though to accommodate the extensive thermal fins. The FA09s is a wee bit less cumbersome. The FA09s has much more neutral tint, maybe 5,000k, and much nicer in that specific regard imo. In initial testing, I wouldn’t shy away from BK-FA09s if I was considering a K70, especially if I like neutral tint.
Yes, introductory was less. When I saw it, I think $134.99 and used a 1x 15% ebay code for 114.7 from HKE. A week or two later it was $159.9 any and everyplace. I got lucky. So far though, it looks like a nice NW alternative to the K70 which is $179. typical.
+1. The holder is a battery vice. I saw on another forum a pic where someone’s carrier simply busted apart when they were trying to get the cell into it. It’s not what’s mean by tight tolerances.
It has a temperature controlled step down, I would say it steps down to approximately half output, when the temperature has dropped it steps back up to max again.
I got mine in the post today and a quick temp/lux test was the first thing I did.
The light was sat in my bathroom with no airflow. Around 7mins30 it decided to drop down to the next lowest power. I didn’t interupt it as I wondered if it’d come back on its own - it didnt. I turned it down a mode and back up, nothing. I turned it off at the bottom switch and back on and it was back to full pelt.