If that’s the case I can’t ever see that light reaching 10,000 lm with a short battery.
10,000 lm / 12 leds = 833 lumens per led
According to Texas_Ace’s tests you need more than 1.5amps to reach 800 lumens.
12 leds * 1.5amps = 18 amps
So something capable of 20 amps (the 18650’s forsh mentioned) might see the specified output but not happening with short cells