That’s a single AA cell light which literally must be using a boost driver, just like the SC5. A 1.5V or lower battery cannot drive a 3V LED without it. That ability to step-up voltage allows for max output that is potentially constant until LVP kicks in.
The previous runtime graph (on a light which could very possibly include a buck circuit) showed multiple stepdowns. Since we don’t know if those are temp, time or voltage based there is little useful info to be gained.
His use of “dropped out of regulation” is correct though… cell voltage fell to a point where the driver could no longer supply full power to the LED. It is simply sucking what it can from the cell and not managing to properly regulate it anymore.
You are again employing a straw man argument. The details of the driver are irrelevant to the meaning of regulation and current regulation when describing how constant brightness is achieved. Each step down on the 1lumen runtime graph showed another, lower level of current regulation, and did not show a steady decline in brightness, but one that is stepped, which is what is expected if the current is regulated such that constant brightness is achieved.
“Not managing to regulate it anymore…” is just the same as “dropping out of regulation.” Obviously, the cell capacity limits how long regulation can be implemented.
No, it’s not irrelevant because the methods used to achieve that can be completely different and in some situations it would be impossible based on LED/driver/battery combination.
Thus far, there are only two methods to achieve constant brightness that I am aware of, which is either by regulating the current, aka current regulation, or what is whimsically called battery regulation, referring to how steady the output is from Eneloop cells that consistently ride 1.2V under load. Hypothetically, if some new method arises using magnetic fields to keep the brightness constant, then maybe we’ll call that magnetic regulation, but it is regulation nevertheless, regulation of the brightness to be constant. How we get there is beyond our scope if the result is precisely the same.
BurningPlayd0h, it is more than obvious that you are intimately familiar with flashlight driver technology, and electronic design in general, and maybe we could barely squeeze what I don’t know about it into the Grand Canyon. The problem is simply that you are being too rigid with how certain language can be used, but language never sits still and is in constant flux and evolution. No one is going to get confused about this if the subject is driver features realized in perception of the output.
A big part of what I’m trying to get across is that you can try to pull “X” amps from a light all day, but if the voltage doesn’t meet the Vf of the LED for the desired brightness then it doesn’t matter. Only designs that are able to supply enough voltage (especially when the battery is under load) can run higher outputs when the cell is drained… in the best cases even when very drained. That’s one of the things that really special about Zebralights for example: They can step down the voltage (buck) to be efficient on low modes and when the cell is fairly full, or step it up (boost) for high modes and when the battery is drained.
Fair point about me getting hung up on the terms, but I think it just adds to the confusion when a light is reviewed and based on the runtime charts the claim is that it’s “not regulated”. Not “lacking output regulation” or something that really goes any way to describing the result vs the cause but just “not regulated/unregulated”. I’ve seen this said about lights using 7135 drivers which is just kinda ridiculous because those are literally linear regulators.
Just an example of what that gradual dropoff looks like:
Agreed. The way current regulation must work then is within the bounds of this. Obviously, current regulated lights are not going to take all the current available. They’re going to grab some level below whatever maximum level is available in order to give an output that holds its brightness. Some current regulated lights will only hold their top brightness for a few minutes before dropping to a lower level, but the more impressive ones will sacrifice a larger amount of the current overhead in order to give about an hour of constant brightness. So current regulation will sacrifice absolute extreme top brightness in order to provide a steady output for some recognizably decent amount of time.
I think Zebralight is a great example of current regulation for constant brightness. Though the top mode will usually step down after a few minutes, the level it steps down to generally remains constant right up until the cell is very nearly drained, and then it begins stepping down rapidly to off. But the Skilhunt does a good job too, at least by that graph, which is the last revision of the light, so I’m going to assume the current Skilhunt driver version is a little better than that, at least.
If the manufacturer doesn’t say, I expect the constant brightness not to be there, and the reviewer will simply confirm that. If the output graph is a diagonal line, that means “unregulated” whether there is actually regulation there or not. Absolute engineering and scientific accuracy isn’t really necessary to describe what’s happening, the reader should understand the light will steadily dim as cell capacity is depleted.
I am familiar with it, have spent 3 years exclusively using direct drive incan. Good cells matched wtih certain lamps do sort of have built-in regulation, but seeing that gradual dimming is difficult in lower amp lamps, until they drop off a cliff around 3.5V. It is easy to take notice of with the higher amp lamps. In regard to this contentious vocabulary, whether that light charted is regulated or not, by the output graph, it is understood to not have current regulation for constant brightness.
Here’s the crux of what bothers me about that vocab though, what allows Zebra and most of Skilhunt’s models to maintain such a consistent output is control over voltage, not current. (Also just realized that since the M150 can use AA it will have a boost circuit as well. IDK if that operates at all within the voltage range of li-ion when 14500 is used though).
Yes, the S2+ doesn’t show a regulated/stable output but it quite literally does regulate the current. That’s why a light listing “regulated current” as a feature could lead a buyer to assume it will maintain constant output through a cycle only to find out that it isn’t the case at all - and it wouldn’t be false advertising either. Much harder to look for lights that have that quality without waiting for a reviewer to take the time and effort to post runtime charts. I’d just way rather people say “stable/stabilized/consistent/constant/flat/regulated/etc. output” and then none of us have to guess what is being discussed.
Since the zebras are not great throwers anyway, my preference is for the "F" (frosted lens) models. The frosting blends the light, so tint is uniform across the beam. As a bonus, you get a wider, less defined hot spot. I suppose (on rare occasions) you might still get a tint you don't like, but blending guarantees there are never any weird color rings in the corona or elsewhere.
I also have a preference for high CRI and neutral tint, so my favorite ZebraLights are the "Fd" (frosted, daylight) models.
If controlling the current won’t achieve constant brightness, then what effect is there to controlling the current? Also, because as the cell is depleted, voltage and current will drop, isn’t controlling the voltage also effectively controlling the current?
I am a little disappointed, did not actually notice that was an S2+ until you pointed that out… I thought the S2+ current regulation resulted in constant output. So what is the point of current regulation in the S2+, what does it do, since it isn’t providing constant output?
Perhaps the best light for you is simply a battery attached to a sw45, no switch, no reflector, no lens, no driver, no host, just a cell and an emitter, since that is apparently all that matters to your highly refined and well-researched preferences. And in this regard, if all you care about is tint, why are you bothering with LED at all? If you knew anything at all about tint, you’d be carrying a decent incan.
That Noctigon really a great light, if you like that like that sort of thing, but that won’t run on an Eneloop, and 2000K isn’t tint, and until you compare with a decent incan, you don’t know what you’re missing. My point wasn’t really that, but simply that what makes a good flashlight goes well beyond tint, and tint is only one single factor, and nothing is just right for everyone. If we can look beyond tint, and we really can, Zebralight makes a decent flashlight for having a number of other excellent qualities. AA. Runtime. Constant brightness. Interface. Host. etc. You might see how foolish I am for saying something like, “Noctigon sucks because the clip is horrible!” Its absurd.
Been using a SC63W second hand purchase for about 2 years now. While I’d love to upgrade to higher CRI I really won the tint lottery on this one and would hate to go back. Nice creamy beam with a hint of yellow. Feels like higher than its rated CRI, too… but thats what good tint does for you!
