Wattage and efficiency discusson... and ?'s

LED Flashlights – General Info
1

I have been comparing my TR-J12 and Apex 5T6 over the past week or two, and the one major difference I can’t explain is the difference in Lumens / watt efficiency.

Both are 5-XML lights T6 flux BIN, and pale tints.
Both use reflectors similarly shaped, and you can see from the beamshots the dispersion patterns and overall outputs are very similar. The Apex is a little more floody though. Ceiling bounce comparing the two is pretty much identical.

The Apex draws 5.3A from 4 parallel 18650. So assuming nominal cell voltage that equals 18 Watts (5.3A x 3.6V)
The TR-J12 draws 3.6A from 2 series 26650. So assuming nominal cell voltage that equals 26 Watts (3.6A x 7.2V)

Thats a difference of 8 Watts power consumption for nearly an identical amount of light OTF between the two. Both lights are around 2000 Lumens OTF I think.
The TR-J12 does get a little warmer to the touch, but not alarmingly so. Both lights will get hot after ~10 minutes in stagnent ~85F air, but neither light really suffers from “thermal runaway”.

So my question is where are the extra 8Watts of power going on the J12? Is it that 8W looks like a lot on paper, but in real life really doesn’t translate to that much energy?

TR-J12

Apex

2

Most likely it’s just that your measurement on APEX is way off the scale, with currents so high you need to use a current clamp instead of DMM to measure it accurately.

3

Also with four cells in parallel, I would expect them to experience far less voltage sag. At 5.3 Amps, only 1.325Amps is being drawn from each cell - with fully charged cells, I would expect the voltage drop from full (4.2) to be more in the 3.9-4.0V range…

This in and of itself bring it closer inline with the trustfire (5.3 * 4) = 21.2 Watts.

Also, like Shadowww says, it likely draws more than 5.3 Amps when a meter isn’t inline.

PPtk