What battery option yields more output from your flashlight?

[nickdizonc]

I've been getting confusing feedback from manufacturers about whether output is affected when using 1 X 18650 or 2 X CR123A batteries. So I'll just ask here for another data point for me to ponder. Will a regulated light produce more output with 2 cr123As or a single 18650 batter? Logic says yes because 2 X CR123As has a higher combined operating voltage. I'm just curious because for example my PD35 absolutely puts out more light when fueled by 2 CR123As vs a single 18650. I always thought that with regulated lights there wouldn't a difference as the current is controlled. Again, this is strictly an output question. I understand 18650s will yield longer runtimes but I'm only referring to output.

 

[Chodes]

It will depend on the driver,the light's resistance, the LED's Vf and what 18650 you are talking about.

 

[BringerOfLight]

Most of those 1x 18650 / 2x CR123A 'regulated' lights have a buck driver and are only semi-regulated at high outputs. As the 18650 voltage drops while it's discharged, the light will not be able to run at full brightness anymore (the buck driver can only lower the voltage).

There are some lights that have a buck-boost driver (e.g. Zebralight, Armytek, Spark) that can run at full brightness regardless of the 18650 charge state.

 

[oldvultureface]

I'm just curious because for example my PD35 absolute puts out more light when fueled by 2 CR123As vs a single 18650.

Same with my SRT6. Measured with a photography light meter, two CR123As put out two-tenths of a stop more light than a single 18650. (A one stop increase is double the amount of light.)