I have checked around trying find an answer, but some findings are conflicting. How many amps do lights like the L2 versions of the TK75, TN30 and the like draw? I have found answers from 5-6 amps, but that is the older XM-L types.
I know multiple batteries helps with sag, but I’m trying to use the battery comparator for different batteries and don’t know how high to set the amps.
A XM-L (or XM-L2) led is 3.3V and 3A, i.e. about 10 watt at full power. With 3 leds it is 30 watt or 7.5 watt for each battery (4 batteries).
7.5 watt is between 1.9A (Full battery) and 2.5A (Empty battery), if the driver has 100% efficiency.
Without exact measurement of the light, assuming 3A draw will be most correct.
The above estimate works for both serial and parallel batteries.
Excuse my newb question, but would that be times 3 for 3 emitters? Or light would be drawing 5.7 to 7.5 amps total?
I have no idea how these things work, but I’m trying to learn.
Watts is watts. The volts & amps may be different but 3 x 5 is still the same as 5 x 3. That's the whole reason for converting to watts, it makes the input & output directly comparable.
No, I did factor in the 3 emitter in the calculations.
The current draw was calculated per battery, if the four batteries are in parallel the total draw would be 4 times the per battery value.
It took a while reading and re-reading to figure out what you were saying, and after I did, the graphs you have made actually made sense as far as what battery might be best for certain lights, run times and cutoff…
Thanks lots… 
Ok, I just measured the tailcap current on my TN30 XM-L2 version and it was just over 3A like 3.051A. Now can someone explain to me what that reading means? Does that mean that each emitter only gets 1A?
It has 3 batteries in series, i.e. you are only measuring the current for one battery.