Why?
Yes that’s true what Enderman said.
Now take the case of the DCQ Tiny mentioned in the link above.
It runs 7(!) XPG2 emitters on 1 x 26650.
How does it do that?
By having a very efficient boost driver. The Zebra SC5w also has a very efficient boost driver to enable it to pump out 500 lumens on just 1 x AA Eneloop.
The point being that not all boost drivers are blanket equally inefficient and subsequently they’re not the same. Just like a 2 x (or more) 18650 in-series light that needs a buck driver while also partly inefficient because of energy lost through heat doesn’t mean one should never bother using a buck driver either, right?
There’s no perfect/exact 1 to 1 outcome when you mess around with an original state of electric charge. At least not that I’m aware of on this planet. :student: :laughing:
The fact that it pumps out X number of lumens alone says nothing about its efficiency.
“More efficient” would mean delivering more light output for a longer period of time from the same amount of stored energy. But in fact, as was stated earlier, a boost driver causes more current to be pulled from a cell, and the higher the current draw, the lower the energy (Wh) is. So in fact, it’s less efficient, not more efficient.
Take a look at this table from HKJ’s review of a regular Eneloop AA cell:
You’ll see that the more current you draw, the less capacity (and energy) you get out of it.
So are you also gonna tell me that buck drivers in total are more efficient regardless of their quality?
Because I can tell you right now there ARE boost drivers that are a lot better than other boost drivers because of their design application to the specific light it supports and the quality of its materials.
The DCQ Tiny and the Zebra SC5w are proof of that.
And all I’m saying is that I wish more flashlight makers could give us more likewise NiMh AA options. I’m not disagreeing with you btw that boost drivers don’t have efficiency issues.
But I do disagree that they’re ALL just too inefficient to even bother.
You’re missing the point. Any time you ask for more current from a cell, your efficiency is going to go down. No driver can bring that efficiency back.
Nobody said that. We are just saying that there is a tradeoff. You get higher light output in exchange for lower efficiency. If you must have that higher light output, then you might be willing to accept that lower efficiency.
Instead of bothering with boost drivers, just get a flashlight that uses larger number of cells. This way you can get high overall current (or voltage) and still have good efficiency. Granted, you are going to end up with a larger/heavier flashlight. Again, there is always a tradeoff somewhere.
To be honest I’m not getting your point because I’m fully on board that boost drivers have their efficiency issues. I really do understand the trade offs.
I’m also fully aware that when I can stick a single AA Eneloop in an SC5w it gives me amazing performance out of that paltry 1.2v’s. It may not be as ‘efficient’ as that 4.2v lithium that enjoys a 3 Vf emitter and a more efficient driver to start with but hey it does pretty dam well considering it weighs inherently about 0.6 oz less than the 18650 much less size is more for an EDC - usually. I’m not comparing an 18650 to a AA Eneloop mind you because there is no real valid comparisons to be made.
Back to my original point I’d rather have an ‘inefficient’ well-designed/constructed boosted driver and a single AA Eneloop over a 14500 any day. Remember I’m only talking about AA size here. Well ya might as well throw in AAA Eneloops over 10440’s too while we’re at it.
But regardless of these gosh darn awful inefficiency trade offs I somehow can still live with a boosted driver or two. :laughing:
IMO, boost drivers are great in two ways:
1. (and the most important) They allow for constant output regulation.
2. They allow you to use LEDs with a higher forward voltage than your battery. This might include brighter and more efficient LEDs than are available in the 3 volt range, such as the XHP50.2 or XHP70.2. Or, simply to be able to use any LED with 1 AA cell.
By itself, a boost driver doesn’t add any efficiency. Go direct drive if you want efficiency, especially if your battery voltage is matched well to the optimal forward voltage of the LED. The problem is that direct drive isn’t constant output. The other problem is that the only way to get lower modes with direct drive (such as FET) is to use PWM, and that means a very inefficient lower mode (because you’re overdriving the LED for no benefit).
Zebralight does make pretty efficient boost drivers, though, and it’s tough to beat their flashlight’s overall efficiency numbers.
But why? Overall energy (Wh) of an AA Eneloop Pro is about the same as Li-Ion 14500, so there shouldn’t be much difference in performance, assuming you’ve got the appropriate driver for each. You are going to have to draw about 3A from an Eneloop cell to get similar power that you would get from a 14500 cell at 1A.
Overall, a 14500 format is not very impressive when compared to other Li-Ion cell sizes, but again, I don’t see how it’s worse than Eneloop from an overall energy standpoint.
I didn’t have a say in them designing emitters with a Vf at 3v’s. So now I’m stuck with all these AA Eneloops that in single use are useless unless boosted. Man if only emitters were 1.2 Vf we wouldn’t be having this interesting back and forth. :laughing:
So now what am I supposed to do? Well I can buy for example an SC5w and be pretty happy. Again, I do wish that we had more choices but that’s the way it goes.
In general the 14500 doesn’t like high currents. The AA Eneloop does. Especially the AA Eneloop Pro.
So yeah, I still contend in general an AA Eneloop is superior to most 14500’s. :sunglasses:
It is not amperage that matters though.
It is overall power.
If you were to push 5A out of an NiMH cell, you would get 6W.
If you were to push 5A out of a 14500 cell, you would be getting 18W.
Eneloops are about equivalent to 14500 in terms of energy density, can sustain more cycles, but need a powerful boost converter to work with most electronics when not in series, can deliver less power, and are safer.
I give up.
Ok, is it more ‘efficient’ if it drops below 2.75v assuming it’s unprotected like the Eneloop and then suffers damage? That’s another beauty of the Eneloop NiMh. I don’t have to worry about it going below a certain voltage. Then when I recharge it I don ’t have to worry also about the consequences of that damage either.
Somehow the discussion veered off that I would be better off with multiple cells so that an inefficient boost driver wouldn’t be needed. Ok I get it.
Again, the WHOLE POINT was I wasn’t talking about that. I was talking about a SINGLE Eneloop AA NiMH vs a single 14500 and I wish we could see more boost driven SC5w’s in the flashlight universe. Cheaper ones at that.
Besides I hardly run lights all the time full blast and so when I do go into lower modes an Eneloop NiMH doesn’t waste energy by extra heat that a single 14500 does.
I think that makes a single cell BOOSTED (Egads!) (regardless of it’s inherent inefficiencies) 1.2v Eneloop NiMH EDC (with some serious output IF I need it albeit for a shorter time) STILL a desirable thing and in a different way uniquely efficient. I contend it’s still superior to a single 14500 all other things considered. Hey but that’s what I think. Everybody thinks different as to support their whys.
Anyway, somehow all this became a big head scratch to one poster in particular on WHY. Well, see all the above OTHER comments too in support of the WHYS of this format.
Bottom line IMO Eneloops still are the most underrated batteries around and more boost driven options should be available. Cheaper if possible. :sunglasses: 
Hey was all this worthwhile to anyone? :laughing:
I don’t blame you. I would too. :person_facepalming: :laughing:
Technical note:
Vf determines the wavelength of light output. Bluer photons have higher energy than redder photons, so you need a higher Vf to get bluer photons.
Red LEDs have a Vf of around 2V. Blue LEDs have a Vf of around 3V. The reason a white LED also has a Vf of around 3V is that it’s actually a blue LED coated in phosphors that downshift some of the photons into the rest of the spectrum.
An LED with a Vf of 1.2V would actually be infra-red, like the ones they use for TV remote controls.
Yes. Good info but to clarify I was inferring only to white emitters for this topic.
Fact A: Small format lithium batteries like 14500 and 10440 are not as good as 18650, even after accounting for the smaller size, because they have not had much R&D investment, and thus remain relatively undeveloped compared to 18650 or even 26650. 21700 appears to be the next 18650 because of the big money from Telsa and the like going into its R&D.
That said....
IMHO A: I think that if Zebralight designed a pure 14500 powered equivalent of the SC5, with a zebralight-quality driver to take advantage of the 14500 battery, it would probably have a longer runtime than the SC5, if you used a good 14500 battery. I think thats because its possible for lithium battery drivers to achieve higher efficiencies than NiHM drivers, if you spent the same amount of money, in addition to to slight advantage that 14500 in its current form has in energy density.. The advantage disappears above 2 or 5 Amps, there is no denying that eneloops work better at high currents.
But if you need above 300-500 lumens for a useful period of time, then a 1xAA or 1x14500 light is not the right one for you! 
Fact B: The size of the internal contacts and such of a cell take up more space, relatively speaking, in a small cell of any kind compared to an equivalent chemistry larger cell. Thats why Tesla is moving to 21700, because it has more potential for future improvements than 18650, despite being only 3mm longer and 1mm wider.
Why not larger? I'm not sure, apparently the risk of the chemical inside getting "stuck" at a hotspot or something increases with larger batteries.
I have heard this so many times, even in this thread, but I have yet to see any response as to why it needs R&D. Is the construction of this item that can be sold at a profit for $4-$5 really so complicated that scaling it down results in major inefficiencies? What is difficult about it? Which components do not scale efficiently?
The volume of an 18x65 cylinder is 16540 millimeters3
The volume of a 14x50 cylinder is 7696 millimeters3
14500 is 47%
So the capacity should approach 47% yet common ratings are more like 25% of an 18650.
I can understand some loss because the end caps and side walls are likely the same thickness as the 18650, so the internal volume may be more like 40% compared to the internal volume of an 18650.
Still, from 40% to 25% is a big loss, explained by which components not scaling, and why? What part needs development?
At 40% there should be 1400mAh 14500’s out there, best I have is 800-850.
I have a couple of Zebralight SC52’s. They take either a AA or a 14500. (Zebralight later dropped the dual-chemistry design.)
Whether I use a regular 1900mAh Eneloop, or a Keeppower 800mAh 14500, I get about the same run-time on all modes.
The 14500 cell in the SC52/SC52w wins for regulation on maxium and output on max. A 14500 gives 500 lumens for a minute, then a very well-regulated 280 lumens after that. On an Eneloop, the max is 280 lumens, but it strains to maintain that as the voltage drops and is not very well regulated. It’s well regulated on other modes, though.
Zebralight obviously improved their driver in the SC5, since it gives a well-regulated output of 500 lumens on an Eneloop. Perhaps that’s why they dropped the dual chemistry support, it made for a less-optimal NiMH driver?
Anyway, if the SC52 is any indication, I think 14500 wins, simply because of the better regulation and output. But, if you compare it to the SC5 performance, Eneloop and 14500 are about equal.
Another light I have, the Manker T01, is a good performer on an Eneloop. About 400 lumens, though it’s not well regulated. Definitely inferior to the Zebralight SC5, but it’s the only other high-output 1xAA light I have. The Manker also can use a 14500. It does give a slight boost in output, but I’m rather unimpressed by it. I expected better.
It may just be that designing a light that takes both NiMH and lithium-ion chemistry is too difficult. I think Zebralight made the right choice in doing just one or the other, and do it well.
Overall, though, I have to give the edge to 14500. Not by a huge amount, but it does provide more power if you need it. The Eneloop is more impressive, though, since it’s surprising what it can do with a lowly 1.2 volts.
I keep asking WHY in hopes you would actually do some homework and provide some data/examples to substantiate your claims so that we could learn something. Otherwise, it just sounds like a bunch of personal opinions, not supported by any facts or data.
For example, this one:
What is the basis of this claim? How did you come to this conclusion? Why do you believe a 14500 wastes energy in lower modes (lower current), unless maybe if you have a bad driver, not well suited for a 14500 cell? As you can see from the table below for a 14500 cell, the lower the current draw, the more energy you have. Completely opposite of what you’re claiming.