confused on tailcap draw xpg2

Hi all. I just put together my ultrafire 14500 light with an olight 3.04 amp driver and an xpg2 on a copper noctigon 16mm star. What I don’t understand is why my tail cap reading is only at 1.655 amps.I am using the same meter that I tested my other light with and it was dead on, as advertised. I’m running a battery that’s supposed to be safe with that kind of draw. Just not sure why its not pulling closer to the 3 amps. I would greatly appreciate any input. I am not planning on using the high mode often but would like it (if only for showing off my little pocket rocket) to be working for short insane bursts. Thanks. Matt

Depends on your 14500 you are using, 3A is not exactly easy for a 14500.

Have you soldered wire or braid on the tail (and battery +, if applicable) springs?

Edit: Also, what size (AWG) wires are you using from the driver to the emitter?

Edit 2: I was just testing a light, and switching from 22AWG leads to 18 AWG leads on my DMM (in series with the emitter lead) caused the emitter current to go from ~2.5 amps to ~2.85 amps.

Don't waste time with wiring upgrades, braided springs, etc. The small cells can't do that kind of current, nothing you do to the light will change what's inside the cell which is the limiting factor here.

If you are curious, wire some bigger battery like 18650 to the light to see if the battery is the limiting factor.

I am running the Efest IMR 700ma. I will have to check some of these things. Thank you for the input. I will recheck everything at work today with a better quality meter. And try running the setup with an 18650

I re-soldered pill to driver, looks ok. measured no resistance through them. rechecked with a better quality meter and got same readings. I will try it later tonight with a good 18650. thanks for all the input. I had read E1320 was pulling big amps from these little guys. We will see if I can get this thing rockin’. The light is very bright, its just not all it can be yet. :wink:

I have two little cr123/16340 lights I've built with 8x7135 105C drivers & XPG2s, I have a few 16340s, some good, some average, and they all run at around 1.7-1.8A at the tail despite the drivers that should be doing 2.8A. Shorting the LED- to GND makes it go direct drive and bypasses the driver, and current doesn't increase and the light doesn't get brighter. With the pills removed and temporarily connected to a good 18650 they run at 2.72-2.78A. One of the lights uses the same pill threads as a P60 and with a XML2 & the same driver it runs at the same tailcap current, so it's not the LED or anything else, it's just the little cells being weaker than what you've come to think of as 'normal' with 18650s.

I have both trustfire flame and efest 16340 cells, neither will allow a mini 02 tlf to run on high at full charge - protection cuts power because the draw is too much for the cells. As comfychair says, run a half decent 18650 to test the circuit bit odds are on that your asking too much of both the cells and the host. That’s why I plan on building a few sub 2a 16340 hosts to use my cells and bite the bullet and buy some aw 16340 imr cells for the mini 02.

Well I figured it out. I had been doing capacity tests on my new efest 14500s and thought I had charged them back up. As it turns out I had been testing amp draw with a dead battery. :frowning: very embarrassing. I normally would have checked that first (bonehead) thank you for all the replies. I am now getting 2.75 which is about what I was expecting.

That would do it :)… Glad you were able to figure out the problem!

Glad you figured it out, amazing how a bit of testing and playing can drain a small cell isn’t it?

I have a few direct drive tiny lights that are custom made, running on 10250 cells. With a fresh charge the light starts at over 3A. That doesn’t last long at all as the XM-L or XM-L2 rapidly takes the 80mAh cell down.

The .50 BMG light that is pictured in my Avatar runs on a Q-Lite 3.04A driver and it’s XP-G2 R5 pulls 2.82A from an AW IMR14500 cell.

I’ve pulled 2.4A from an Efest 10440 direct drive to an xre when a TF cell could only deliver 1.6A. That was enough for me to stick with imr type cells, at least for single cell lights.

Maybe I should revise the description of my 16340s from 'some good, some average' to 'some barely mediocre, some awful'.

all you get in high when fully charged is a flicker then medium. on a jury rigged 18650, I can get all three modes, it does it with two different pairs of protected 16340 cells so I figure it most be the protection, particularly since rey specifically said that it will trip the protection on high, he asked for higher current protection circuits to be fitted but they were not. I’m not grumbling because over 2a is well over 2c for these cells, sometimes restraint is wise.

Through a similar malady I learned to test voltage of the battery before testing current draw . . if you’re keeping notes that can help when comparing different batteries or testing at different times.

Yes. Notes would help. At the time I’m just positive I will remember……they say it just gets worse the older you get. :slight_smile: