hi,
I did a similar tailcap mod not long ago to tame the KL6, using a 47 ohm resistor. after 20 hrs, when switching to "high" mode, there was just a little brightness drop compared to "high" on fresh batteries. I stopped the runtime test (two RCR123 batteries, 650mA) after 30hrs because I got tired of it, the light was still putting out about as much light as a fenix L1P. so, yes, you should get a significant increase in runtime (although you are loosing some energy by converting it to heat in the resistor). your runtime should be even better than mine, considering the fact that you are using a 100 ohm resistor. the only other resistor I have here right now is 140 ohms, and the KL6 is still pretty useful with that one.
the following is just theory, but nonetheless: I suspect that if the resistor value is too low, the converter will try to stay in regulation and draw more current from the batteries, making up for the drop in voltage and thereby just consuming energy for heating up the resistor while doing northing to increase runtime. can someone with more knowledge on converter electronics maybe comment on this? :huh2:
by the way, my modded Z58 switch is not a "twist for on\off, click for high\low", as I hate to loose the clickie and even the "momentary on" switch. so I figured out a (non-trivial) mod that uses resistor in a way that preserves the clickie function for on\off and lets me choose high\low\lockout by twisting the tailcap. this still has to be proven for reliability on the actual flashlight though (don't have my leef C-M-body yet).
