Incorrect in the rated mah and amps? Or incorrect in saying that they would work?
Because, They would technically work, but depending on the quality of the cells, you just won’t be using the full potential of the flashlight. And the voltage would sag more and maybe trip the LVC and step down sooner.
Also, I am able to use super old 18650s from old laptop batteries just fine in a FW21 Pro, I just can’t use Turbo mode at all, because it instantly trips LVC.
It’s my understanding that the drivers in these flashlights don’t “force” X amount of amps regardless of battery, they “ask” and then the battery gives what it can provide (depending on internal resistance, the lower the better).
In any case IMR/INR cells are better with the 30T for “max amps/output regardless of runtime”, P42a and 40T for “all around Amperage/Output and Runtime” (with the Molicell slightly better in my testing).
ICR cells will work (samsung 50E), but voltage will sag a lot and won’t provide maximum ouput like IMR/INR batteries can, but they will last much longer in all modes besides turbo.
Considering my personal experience I would first go for Molicel P42a, if those aren’t available, then Samsung 40T. I don’t really see the point of the 30T as it has much lower capacity with only marginally better output only when fully charged.
Go check Mooch’s and HKJ’s battery reviews, They are well respected by flashlight/vape enthusiasts and agrees that 30T is for “max output” and the Molicell P42a is slightly better than the 40T.