Re: 123 Cell Extender adapter for SureFire E serie
IIRC, KL1 works in full regulation at V around 4V. that means, once you go with 6V (2 123 input), you will not see noticeable increase in brightness if you change to 3 123 (9V). but of course, you get longer runtime
ALso, KL4 is not supposed to be run from 3 123. It is meant for 2 123, most are lucky it runs from 1 123. if you run your KL4 from 3 123, you risk your lux and/or the circuit to be burned down to death.