Why people like CR123A flashlight?

[coman]

I know many famous brand's 1xCR123A flashlight can not use 1x16340 battery, any one know the reason?

 

[Brasso]

The 16340's are 3.7 to 4.2 volts. 123's are 3v. Some lights just don't have a driver that can support the extra voltage.

Also, the tighter you can keep the voltage range, the more efficient you can make the flashlight.

 

[Imon]

Most of them can the manufacturers just doesn't recommend it because the higher voltage of the 16340 can driver smaller flashlighters harder to the point of them damaging themselves.

 

[Erzengel]

It is not easy to develop a driver that works efficient on the whole voltage range from two nearly depleted Cr123sup two freshly charged 16340.
and You need a battery protection circuit which doesn't keep You from pulling all the available power out of the primary cells.