Maybe it’s been already commented, but how come a 3.7V cell when charged measures 4.2V?
Why not calling them 4.2V directly?
It’s confusing, because at 3.5V my flashlight already drops the turbo mode, ramping down in steps and blinking, yet you would think that 0.2V from the nominal value is nothing.
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I think I’ve asked this before somewhere, but I can’t find it, so I apologise if it was on here:
With Anduril 2 in its default 7 steps, approximately what output percentage does each step equate to assuming no changes have been made to the initial configuration?
Reason for asking, with Convoy’s 1%, 10% etc. output modes if I know it’s a 5A driver I can work out ballpark figures for runtime. I would like to be able to do this with my Anduril lights too.
About 6/10ths down the page, should give you decent scaling.
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Yes it’s called Haitz’s law.
The 3.7V is a nominal “average value” that is useful for calculations, especially when comparing battery performance across different chemistries.
If you want to determine the energy stored in a battery, you need to integrate the below curve (voltage versus mAh discharged) to find its area, which is a difficult task. However, if you were to smush that area into a rectangle of equal base (thus preserving the mAh rating), then its height would be around 3.7V. This is the average voltage during the discharge, and you can express the area (and thus energy) as a much simpler expression: (mAh rating)*3.7V, no integrals involved.
In other words, the 3.7V nominal rating enables you to apply the naive formula (energy equals V times mAh) despite the fact that voltage is not a fixed number.
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Thanks a lot, q/p!
Super explanation!
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Another question.
I was looking at flat EDC lights the other day, and I couldn’t help but notice two things: enthusiasts’ ones are überexpensive, over 100 £/€/$ for a non replaceable batter flashlight is way too much. Inevitably, I then had a look at the cheap ones, and couldn’t find anything with an emitter that is less than 6000 or 6500k.
Why is that? Why cheap short range lights always use unpleasantly cold emitters? Would it really cost so much to use another emitter in a more pleasant (to many) cct?
Edit: I corrected all the typos, which were courtesy of my phone keyboard from F-droid.
SImple, cool white looks brighter and as cool white emitters are generally more efficient than warm white they can usually hit higher outputs. Most average people don’t know what the heck a lumen is anyway, but they know that more of them = better, hence brands aiming for the mass market know that they’ll sell more lights based on the lumen numbers.
I’ve made my peace with it, I bought an Arkpro because it does flood and throw and it’s flat so it’s very easy to carry. It also has a really good battery level indicator, a great UI and USB-C charging. My Nichia and 3000K SFTnn lights have much nicer light, but sometimes I just need to see stuff in the dark.
wait, also the expensive ones are in 6000k flavor?
The Arkpro is what I was looking at and I would love to have the disposable income for buying something I don’t really need… I am sure its UI is fantastic (I can see part of that from the photos already).
Thanks for the explanation, it sounds a bit like megapixels in cameras (for the part the common user doesn’t know jack s, and more megapixels for everyone means a better image, it then doesn’t matter if it is a rubbish one thanks to the plastic cover of the lens) 
Yep. There is now a “neutral white” Arkpro but it’s still on the cooler end and low CRI, plus the “neutral white” is only on the flood emitter. Actually the cool white one has pretty good tint, it’s cold white but it’s not green.
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Big fan of the Vapcell F15. 1500mAh capacity makes a trinket into a useful light. Runtime is preferable to turbo in my uses.
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Hmm, 3A while the driver pulls a max of about 5,5-6A. Makes it a bit over half the max output, so possibly ~800lm+ in a KR1AA.
Wish there were more tests of the ntg50 available, but from what Hank showed in his thread, at ~1,5A/6V the led should still put out ~1000lm, minus losses possibly 7-800lm so dead on with calculations above.
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I can eyeball the outputs on a vapcell h10 and an f15, though I’d hate to ruin a perfectly good f15
I don’t think a couple seconds would do any lasting damage though I’m no expert
Visually, very little difference. Generally inconclusive, since i did not test with any reading equipment…in a white wall comparison against an Olight marauder mini, the h10 was barely brighter than the f15.
In short, the f15 is going back into my d3aa, the h10 is going back to chilling on my desk, and the NiMH is going back into the kr1aa.
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Due to the thread title, I can ask why is the F15 at risk here?
The F15 not rated for 5+ Amps continuous, although bursts hypothetically should be OK. The H10/K10, on the other hand, are rated for 5+A continuous discharge.
I can speculate or point out any number of reasons not to exceed a power rating, but I can still count at least 5 on one hand alone…
Safety questions are never stupid, from my limited time and experience on this rather hostile environment of a planet…
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I have an F15 in my KR1AA. I don’t foresee any real problems. For one I hardly ever use 150/150. In fact, I disabled Turbo and set top of ramp at 120/150.
Even at max, I tend to think short … like 10 second, use of turbo wouldn’t do more than maybe losing a few cycles on the cell.
Of course I wouldn’t use the F15 for long (30 seconds) output tests on turbo. Not necessarily because I think I would have a catastrophic failure, but rather, because I have lots of H10s around for that.
Of course if one wants to be as careful as possible, sure use a cell with higher continuous discharge rating than the highest current expected in the circuit.
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Hmm, I run all my TS and HD10s, and all my D3AA on them.
I also run my d3aa on the f15, turbo disabled, ceiling set to (-76). The only times it hits max are during some blinkies, and lightning storm. I havent tested the bike flasher nor candle yet.
My kr1aa each get a NiMH.
**my ts10 doesn’t physically fit my button tops, so i use the included cell
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