Anything that will replace NiMH soon?

What you say is 100% true, but also 100% irrelevant. What does it matter if a short wire is 100% efficient? The whole purpose is to measure the efficiency of a total solution.

If you have a real-world example of an efficient light that uses a FET driver, let’s see it.

…bad news for Duracell and Energizer users. :expressionless:

Light output and efficiency is not subjective, but is easily measured and is a very important metric with lights. With a driver one of the important parameters is how well it drives the LED and the “well” covers brightness and efficiency.
Efficiency of direct drive can be anywhere from below 1% to near 100%, this depends on what you include in it and how you define it, but it do not say how much battery power get converter into light.

You’re right, and that’s sad. (Umm, that 14500s are dead-ended, not that you’re right.)

14500s are not AA drop-ins, ’cause a lot of things won’t take well to being hit with 4V when they’re expecting 1.5V. Certainly not with series-connected cells. Motors (shavers, etc.) will run obscenely fast, hotwire bulbs will have a short fraction of the lifetime, Si-based goodies can let out the Magic Smoke™, all sorts of bad things can happen if the doodad in question isn’t designed to tolerate Li cells.

Joe Idiot who buys 14500s and pops everything he puts them in, will badmouth 14500s like crazy. WallyWorld isn’t stoopit enough to sell 14500s because of all the Joe Idiots running around loose. At least 18650s won’t fit into anything that’s not designed for them. 14500s? The Silent Killer of AA-based electronics…

Now, maybe flat-top 14500s would sell, doodads can be designed to have built-in protection that only cells with a nipple on top would make contact. That might work. But button-top 14500s are a specialty item, and no mfr is going to put too much effort into them except for niche markets like flashlights and… ummm… whatever else might use 14500s without damage.

Being extra pedantic, make a distinction between direct-drive and FET-drive.

DD is just crowbarring the LED right across the cell.

Sucks for Li-ion, but works beautifully for LiFePO4 cells. :smiley: 3.2V from shortly out of the charger to right before giving it up completely.

Here are a couple of pointers:

Edit: and one more: Drivers, how leds are adapted for different battery voltages

Yeah, DD is literally turning the driver into just a wire that lets all power through.
Seems like the people above are having trouble understanding that.

Now they’re trying to bring LEDs into the equation and say “oh it’s not efficient because LEDs are less efficient at higher current” Well yeah but that obviously completely depends on what LED and power source you use and has nothing to do with the driver anymore.

The driver itself, just like a wire, has minor resistance losses and that’s it.
Anyway, the thread is derailed enough so I’ll stop trying to argue with those people :stuck_out_tongue:

Well, not really. They acknowledge that just crowbarring an LED across a cell can result in too-high current, pushing the LED into a low-luminous-efficiency point. There’s little dissipation in the “driver” (wire), but it’s Hell on the LED, and hardly efficient as a system.

Even PWMing it with a bang-bang FET ain’t a picnic, either, ’cause each current spike will still be Hell on the LED.

And trying to “direct-drive” a red LED, or worse, an IRLED, with a right-off-the-charger Li-ion cell will glow red all right, at least for a short time, but probably from incandescence. :smiley:

Whereas a UVLED with relatively high Vf would be perfectly workable.

So youse are both right, but arguing that the other’s wrong. :smiley:

Which can be pretty efficient (most efficient, even) if it’s matched to the load. If not, then the overall system efficiency would stink.

Ie, you can’t take a 100W 120V/220V bulb, crowbar it across a Li cell, and get it to even glow. It might be the most efficient driver to dump its current into the load, but without even glowing a dim red, it’ll stink as a lighting system.

Whereas an LFP cell matched to an LED which’d put out decent light at exactly 3.2V would be an excellent DD solution. In fact, that’s what newer “solar lights” use, vs NiCd/NiMH cells and boost-drivers.

Unless you’re running the LED at about 50 or 100mA, it’s just continuously downhill in terms of efficiency.
You add more current, you get less efficiency.
There is no “pushing the LED into a low-luminous-efficiency point”, unless of course you set a subjective, arbitrary “bar” where you decide you won’t let it go below.
Also the “sweet spot” (usually around 100mA) completely depends on what LED you’re using.

Who makes the cheapest 18650 / AA lights that use boost drivers instead of direct drive?

Zebras are nice but at 4x the price of other lights I feel like there has to be something in the middle.

Hmm to answer the OP. No, Not at this time.

Now please continue the argument.

By DEFINITION, driver efficiency is output power divided by input power.
When you go to and look at LED drivers, that is what the “efficiency” specification is.
Efficiency is this line right here, which you can see in blue.

This is literally what the word “efficiency” means, there is no arguing the facts.

Just because “in your mind” a wire is 0% efficient does not mean that that’s how the rest of the world is calculating efficiency.
PS- if you want to take total “system efficiency” into account, aka both driver and LED, then what you said in this post here means absolutely nothing unless you state what LED you’re talking about, since every LED will have a different luminous efficacy depending on their current-lumen curve, colour, cooling and temperature, etc. etc.etc.
I assumed you were talking about driver efficiency, just like the guy who mentioned 90, because there is no way that an LED and driver combined will get 90 luminous efficacy, more like 5% to 20%
Please inform yourself before trying to twist your argument in order to avoid admitting you were wrong.
Luminous efficacy - Wikipedia

Any single AA torch (Edit, or 2 AA, even a Maglite LED, efficient but horrible choice of LED) will be using a boost driver. Lots of them out there, but nobody tests overall efficiency in reviews, the nearest you might get is comparing run-times, factoring in output lumens, with who knows which cell, then treating it all with a good pinch of salt.

I still like my Olight S15 which has a boost-buck driver that can run on one AA NimH (1.2V), or 2 AAs with an extension tube, sadly no longer made, or a 14500 (4.2V or more). But no point in using 14500, as I have previously explained. It lasts very well with an Eneloop.

Generally Olight make very good drivers, but they are not usually budget priced, except when on offer.

I also like my Nitecore MT22A, it’s a 2AA side-by-side design, using a boost driver, works very well. It is now my backpacking torch, together with a Mammut headlamp running off 1 AA. Not glamorous, but these work. And are powered by AA, rather important to me.

Edit: and they are very light, being made of good quality engineering plastics rather than dumb cylindrical bits of aluminium alloy, like almost everything churned off a CNC machine, where tooling costs are zero, and work can be shopped out to the lowest bidder, and copied.

18650 torches would usually need a buck driver (except for the ones with high voltage LEDs). The only two I have at the moment are a Thorfire C8S, which can run on one 18650, two CR123 or 18350s or 16340s. It seems pretty efficient too, far ahead of e.g. my BLF A6. And a Nitecore EC4S (Cree XHP50), which runs off two or four cells of similar variety, likewise far more efficient than the A6.

Edit: the Nitecore EC4s is also an example of an un-copyable lightweight design, being moulded from magnesium alloy. The tooling for these ultra-light torches must cost a fortune, surprising they are so affordable.

Many P60 drop-ins use buck drivers to cope with many combinations of cells, Kaidomain is probably the best place to look for these, and their hosts. Probably sneered at by BLF as being old fashioned, but they still work well, and make for a very flexible modular system.

Of course; no one’s arguing that. But the curve is parabolic, its slope constantly decreasing from 0 (where m=1).

I’d say that once you hit the peak and lumens go down with increasing current, that’s pretty much going into a low-luminous-efficiency point, no?

For me, once I see that X% current increase gets less than, say, ½X% light increase, that’s already a significant drop in efficiency that’ll only get worse with more current.

So if going from 1.0A to 1.5A (50% more current) only gets me 25% more light, I’ll have to decide whether/not it’s worth it. Or you can just pick a point on the curve where m=0.5 or so, to be “more accurate”.

Absolutely, it’s arbitrary. But it’s part of designing the system.

Otherwise, every idiot with a soldering iron would be pushing LEDs ’til they’re screaming, glowing blue, and well into the decreasing half of the parabola.

If you know that for an XP-L2 at about 9A would be the peak of the parabola, and ±1A wouldn’t make much difference in light output (m being relatively flat), and you’re just interested in peak output (and to Hell with efficiency), then you can do that… with fully-charged VTC5s and when it’s cold outside in a breeze.

Me? I’ll settle for ½ the lumens at a probably ¼ the current.

You kidding? I’m still EDCing a ’502.

’501s, ’502s, L2Ms… throw ’em together in whatever combo, and have an army of drop-ins from CW/NW/WW to UV, IR, red, green, whatever you want.

Whups, SMO reflector a little ringy? Slap on an OP one instead. Aaaah, much better…

You can lego together whatever you want, as long as you got the parts.

I notice you mention ir, ever try a ir led with a filter so no visible light is emitted put it on strobe and shine it at red lights as your coming up to them? Pretty much the same as the opticom system cops use. It’s usually programmed around 14hz. You’ll breeze through traffic. Very occasionally. The ir rate will be programmed something different. But usually 10 to 14hz. Usually in a few seconds it’ll turn green. It has to give all the other sides the yellow and red. Or it’ll stay green while you drive through. Drivers look confused when a red-light only last 5 seconds and then get to go again. But if you get caught it’s a major fine and some states a felony. This is why a flashlight is better then a dash mounted or bumper mounted mirt system. Not to mention if you can find anyone to sell you a mirt system it’s around 300. Compared to 30 dollars for a flashlight. I use a c8 to get good throw. Not much can be said about a flashlight in your car during a regular traffic stop.

Yeah, MIRT systems…

Nah, don’t think that’s used here all that much, amazingly. Maybe on main drags, but not local streets.

IR shows up very well on camera, though, and they have taken to installing those cameras on various intersections (in case of hit’n’runs, etc.).

A light being triggered like that you can almost be sure it’s tagged somewhere, and if a camera’s nearby, you might be recorded doing so.

I think that Manker has pretty decent drivers?

I recently did a moonlight runtime test with a 1xAA E03H. The moonlight, I'm not sure of the brightness, but its around 0.5 lumens, relatively bright.

It lasted 256 hours on a standard eneloop before I turned it off.

I think that means it's efficient?

I mostly want to know what < $40 light will run 20-40 lumens for the longest amount of time

I wouldn’t be surprised if I am being recorded. But I do have a local police sticker and USMC stickers on my truck. But the license plate would give my info. But I’m not to concerned the cops here really only care about drugs. To the point they have been caught planting evidence in people’s cars from hidden go pros. And that made other people’s cases get thrown out and people released from prison because every arrest those officers made can now be contested. And after what they did to me and got away with. They can all go to hell. I won’t say it out here. Only in pm. But let’s say I requested a polygraph test for me and the cop and I would pay all fees and the judge wanted nothing to do with it. They know what there doing to get arrest. I don’t put anything past any cop I’m white and the cop was white. So it’s not a race thing. He is just a pos. I know a few good cops that hell did steroids with me and handed me beers underage at the racetrack. But some of them man deserve to be castrated.