Niwalker Nova MM15MB is only $151 with discount code. 
discount code: 9b4e24
Is that 6800 Chinee lumens?
I think Niwalker is legit. I found the same Niwalker at Going Gear.
That is proper hardcore lumens and depending on how hard it is driven it could be understated!
It is well within Cree’s specs,
It only goes up to 4A so I had to use the specs for the 12v, just double the amps and halve the volts to be correct for the 6v 
However that body is going to get hot fast trying to keep 63 watts of led power cool, and pulling 9.6A out of 2s2p (6v led) or 4.8A from 4s (12v led) for 2.6hrs high runtime is going to take 4800mah 11960mah cells :person_facepalming:
Cheers David
Niwalker is not another cheap chinese brand, they make top notch lights. Reputable US based retailers want $229 for the Niwalker Nova MM15MB.
I stand corrected…looks interesting.
A good light for winter, it would keep my hands warm on the coldest evening walks.
Ask around you can probably get a coupon to get it cheaper?
Don’t shoot the messenger I only pointed out their runtime claims are just a little bit over stated.
Cheers David
Yea but ANSI ratings allows for the light to step down on any setting for it to pass so a 1000 lumen light only has to stay a at 1000 lumen for 60 seconds i think then it can slowly step down till battery is dead and that is how the run time is calculated.