Ok, so I got my first two single mode Sipik SK-68 clones (from Ebay seller "campingsurvivals") and measure the tailcap current -2.62A on a cheap Harbor Freight NiMh cell, about 2.6A on a cheap Rayovac LSD NiMh (+/-1400mAh), and 2.52A on a fresh new alkaline! I am also getting nearly the same readings on the second light I received! No ill effects to the LED (yet). I haven't left it on for more than about 1 to 2 minutes though.
I didn't think these currents would be possible with a single AA and esp. an alkaline! The meter seems to be ok, and I am using homemade test leads made from 12AWG wire. The same meter setup is showing 3.0A on my KD C8 and 1.66A on my XP-G R5 that I put a 1.4A driver into.
Any thoughts? Are these currents real? Can a AA (NiMh and/or alkaline) handle 2.6A?
don't forget the driver is boosting voltage, so the current to emitter is lower than what you're measuring. Figure in some loss for the circuit efficiency and it is actually under driven.
That's about 2x capacity of your nimh, so they'd get longer cycle life at a lower rate, but I don't think it will just trash them quickly.
As for alkalines, I find they don't have nearly the capacity as when used at .5A, but aside from how quickly output decreases, I don't care, they're cheap.
wait until you try a 14500 in that puppy. Mine gets HOT if you're not holding it
Usually to find out how hard is driven a led using some guesstimate logic and throwing some nuber for efficency loss in conversion. Not an exact science but you get the idea on what runtime yo ucan expect roughly and the output.
Sure a NiMH cells can handle it. At least a good one can. That NimH cell you have probably drops to 1v or so under that load, so we're only talking about 2 watts of power compared to something with a single li-on and an XM-L @ 3A which is 10+ watts. The alkaline would have VERY little capacity at that draw and could not sustain it.
EDIT: Just to be clear, if the driver was 100% efficient (which its not), with 2.6A from the cell The LED would be seeing maybe 750mA. You can't forget the voltage. You have to think about the power (voltage x current).
why dont we measure runtimes and simply clock the light until it dims? -- that's a realer measurement and no more guessing, right? My reviews (Xeno, Quark, Romisen, Tank, Worm, ..) all contain real life measurements of runtimes. no guesstimates.
output? -- the manufacturer's ANSI FL-1 Standard rating should suffice :)
I was just curious really. Wanted to see if mine was driven as hard as the ones other's reported. At this point I am wondering if the "driver" is bad, although it must be working since it's boosting the voltage to the proper level to drive the LED. I'll also check tailcap currents to see if the light is being driven as advertised, get an idea of runtime, and make sure the driver is installed properly (I posted a case where my LED's neg. lead had shorted to the ground ring of the driver and therefore was "direct driving" the LED at too high of a level.
actually, that's enough of a good and valid point. thanks for being honest
Out of curiosity i will punch in my DMM's leads into anything i get served on my plate. gouda, goulash, bigos, bratwurst, cozido, cidre, torta, tripas, hamburguesa.
Will feel like Bart Simpson with his new electronic toy
I always measure pull at the tailcap, just to get an idea how hard the driver is pushing the emitter. There is a huge difference in light output on an XM-L when it measures 1A at the switch compared to 2.2A, and it is the easiest way to tell.
Driver efficiency plays a big role, tailcap resistance, quality of the reflector coating, glass lens transmittance. All these can cut from the light quite good, in the end a 800 lumen approximation based on current draw can end up being with 25-30% less. I've noticed that some low cost flashlight companies coat the reflectors poorly compared to reputable manufacturers or even mid-cost manufactures, always looking considerably less shiny than other.
I posted my reply and now there are 6 new ones between Kreisler's and my reply. Now I go to post again and there are 5 more! I can't keep up! (Too many distractions.)
Anyway, so my measurements of 2.5 to 2.6 amps at the tailcap with a AA NiMh or Alkaline are feasible? I'm also comparing to measurements other's have taken (like Cheap Thrills mentions above). I'm assuming these other's measurements are straight tailcap measurements and not adjustments after the actual readings.
If my measurements are real than I don't like this at all! Runtime would be horrible! Moto - if your read this, I want to know what your lights from "campingsurvivals" measure.
I understand the tailcap reading is not the same as the current to the emitter, but I still never expected to see currents this high from single AA's!
yesterday i did 4 runtime measurements of the Tank E09 and the results are published yet in the review of the review thread. the torch, with fresh Eneloops, got burningly hot (amazing!! no exaggeration) so i wrapped it in a wet dishcloth. guys you dont need to be afraid to measure 14500 High-mode's (Sipik, Xeno, Romisen, P1A, ..): simply wrap the torch in a wet dishcloth.
Yeah, trying to compare other's tailcap currents is tough because it seems tough to know what a "true reading" is due to DMM accuracy, resistance in leads, etc. . . Many times you don't know what other's have measured with. (I don't mean to launch into that whole discussion of meters, leads, etc. . .!) Seems you're best to compare with what you know about your own tests and your own equipment and lights.
Seems to me you're more prone to measure too low than too high, so this is why I can't write off my measurements as equipment inaccuracy.
Yeah, remember to divide that by around 3 and a bit to get current to the LED. I often get currents of over 2A from single AA budget lights/circuits.
It doesn't mean the LED is getting that much, we only assume that as li-ion voltage is roughly the same as LED vf so if we see 3A draw from a li-ion we just estimate 3A to the LED.
