P60 xm-l drop-in tailcap readings, HUH?

Flashlight Modding and DIY Parts
1

all right, this doesn't make sense to me, maybe someone can explain it. following are tailcap readings from six P60 drop-ins, and two other well known xm-l lights. i know the DMM is not anywhere near great, but it has been consistent and fairly accurate, at least with regard to cell voltage charge testing. these readings are averages based on multiple tests with different batteries and have been consistent, so if not totally accurate the readings are at least relative to each other.

first two are custom mods, one-mode, solder filled, and without a doubt the two brightest i have or have seen, 900 lumens +/-

1) 1.9 2) 2.0

next two are well known, one custom from erik and one mf uf, both three-mode. these are both very bright, great drop-ins, very close in brightness

1) 4.1 2) 4.0

next is KD warm white five-mode, 3.7, and either KD or DD five-mode (not sure which one i tested, one is mounted on my bike and i didn't take it off, but they are virtually identical in tint and brightness to the naked eye) 3.8

for comparison purposes, xeno v2 ww, 4.1, and drop-in (actually screw-in) pill from KD c-8 that i put in a smaller MTE host from dx which previously had a ssc P-7, then a MC-E, has been run over by a car, and now has an xm-l. it is five-mode, 3.4.

i'm assuming the one-mode set-up has something to do with the readings, but otherwise i am at a loss. shouldn't the higher readings equal brighter lights? maybe this makes sense to someone, or at least maybe the info will be of some use.

2

Firstly the single modes may use a buck driver as opposed to a AMC7135 regulator linear driver which wastes excess voltage. Do you know if they do? If so that could explain lower readings at 4.2v input as the excess voltage is converted to higher current to the LED.

Also, the additional heat-sinking of the 'solder-filled' drop-in coupled with the lower more efficient currents may go some way to explaining the higher than expected output of the lower current drop-ins.

Further to this, with the tailcaps back on and the lights running in real life the higher current drop-ins may actually pull much less as the tailcap resistance will be much higher to a higher current wanting to pass through it.

They're just 3 ideas I had, I still wouldn't expect a 2A drop-in to outdo a 4A current one anyway though, at least not at 'turn-on' before to much heat build up.

3

i am very confused after this read, i absolutely almost do not understand what you are trying to say, haha. i read it twice. may need to edit the post a bit for foreigners, might just be me, i barely graduated highschool.

4

Sorry, do you mean my post? It was a bit confusing. I was basically saying:

1. The single mode driver pulling 2.0 may be a more efficient type, (buck type, instead of linear) so the LED gets more current. It isn't quite as simple as tailcap current is what the LED gets.

2. The lower current drop-ins have better heatsinking, and at 4.0A (heavily overdriven) with not much heatsinking, the higher current drop-ins will overheat quickly, causing more output loss.

3. In real life tailcap resistance will close the gap slightly between the two current readings, as tailcaps tend to provide more resistance to higher currents than lower ones.

5

Don't forget the logarithmic perception of light is at play here.

You're comparing ~700 lumen to ~900 lumen, which should barely appear brighter to the naked eye.