battery real estate and mAh
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mattheww50
Flashlight Enthusiast
The most heavily used Li-Ion is the 18650, so not surprisingly, it is the most highly developed, with capacities up to 3600mAh, or about 13 watt hours per cell. That makes possible flashlights with 1000 lumens and a 1 hour run time at full brightness.
thedoc007
Flashlight Enthusiast
18650 all the way. Equivalent to FOUR high quality AA batteries, and only four millimeters larger in diameter, and fifteen millimeters longer than a single AA. 26650s aren't bad, either. Again, a step up in diameter (eight millimeters larger in diameter than 18650, same length) but also in capacity. 5200 mAh 26650s are now available.
If only dealing with the common AA cell, at least the AA packs more power per weight than the AAA. In the 1.5v arena, my favorite is the AA rechargeable Eneloop. I've ditched all my C and D cell lights now. I do have an LED lantern that I like and it runs on 3 'D' cells, but I just use D to AA adapters so that I can use AA Eneloops in it.
It took me a while to get into the 18650 rechargeable flashlights but now I have a hard time even looking at 2xAA lights. I was raised with the 2xAA mini MagLite and that size seemed to be a standard for quite some time. Now 18650 lights are my favorite.
18650: 3400mAh x 3.6v = 12,240 mili-watt-hours
2xAA Eneloop: 2000mAh x 2.6v = 5,200 mili-watt-hours
A light like the Fenix PD32 (XP-G2) running on a 18650 is the cat's meow in size and performance in my opinion. There are others. We all have our favorites.
It took me a while to get into the 18650 rechargeable flashlights but now I have a hard time even looking at 2xAA lights. I was raised with the 2xAA mini MagLite and that size seemed to be a standard for quite some time. Now 18650 lights are my favorite.
18650: 3400mAh x 3.6v = 12,240 mili-watt-hours
2xAA Eneloop: 2000mAh x 2.6v = 5,200 mili-watt-hours
A light like the Fenix PD32 (XP-G2) running on a 18650 is the cat's meow in size and performance in my opinion. There are others. We all have our favorites.
I would maybe simplify OP's question thusly:
If you divide the mAh rating of a cell by it's weight in grams, which cell (of any size/chemistry) has the highest mAh/g?
For fairness, this should probably be answered both for cell sizes that can actually be used in a hand-held light, as well as those of any size, if it makes a difference.
You could do this based on volume but IMO, weight is more relevant. It's going to be one lithium chemistry or another so the densities are about the same. Conversely, an NiMH AA has the same volume as a lithium AA, but is a lot heavier. Or to put it another way, it should make no difference to the result, but calculating by weight is easier than by volume.
I suspect the answer would be any good 3400mAh unprotected 18650, but I don't have hard data to back up that guess.
If you divide the mAh rating of a cell by it's weight in grams, which cell (of any size/chemistry) has the highest mAh/g?
For fairness, this should probably be answered both for cell sizes that can actually be used in a hand-held light, as well as those of any size, if it makes a difference.
You could do this based on volume but IMO, weight is more relevant. It's going to be one lithium chemistry or another so the densities are about the same. Conversely, an NiMH AA has the same volume as a lithium AA, but is a lot heavier. Or to put it another way, it should make no difference to the result, but calculating by weight is easier than by volume.
I suspect the answer would be any good 3400mAh unprotected 18650, but I don't have hard data to back up that guess.
thedoc007
Flashlight Enthusiast
It might be a little easier, but for practical purposes, I care much more about size than weight (guessing I'm not alone in this). Honestly, 20 grams is not something I would ever notice one way or the other...but an extra quarter inch of width or an extra half inch of length would be VERY noticeable.
Pretty much the 16340 form factor dominates the smaller lights and 18650 the larger lights with the exception of novelty light like the smallest LED lights like the Dqg Spy taking a 10180 and a mid sized, long running, high amp performance lights like the Olight R40 Seeker taking a 26650.
AA and AAA rechargable batteries are almost as old school as traditional. incandescent flash light bulbs.
I can definitely see the smallest form factors getting smaller and the largest getting larger but 16340 and 18650 is over 90% of the single hand held LED flashlight market and will be for probably at least the rest of the decade.
AA and AAA rechargable batteries are almost as old school as traditional. incandescent flash light bulbs.
I can definitely see the smallest form factors getting smaller and the largest getting larger but 16340 and 18650 is over 90% of the single hand held LED flashlight market and will be for probably at least the rest of the decade.
thedoc007
Flashlight Enthusiast
If you believe that, you are spending way too much time on this forum. By FAR the most common battery is AA. CPF is a tiny niche market, and not representative of the total market in any way. 18650 might be the most popular here, but it is patently ridiculous to say that it dominates the overall market for handheld LED lights. Most people have never even heard of 18650 or 16340. And virtually everyone has a flashlight of some kind, so clearly they do not represent even a majority of the market, much less the overwhelming dominance you claim.
AAA is also quite popular, even here on CPF. CR123 sized lights are too big for keychain carry, for most people. But AAA lights can be quite compact, and plenty bright enough for most EDC tasks.
I was going by what is currently being sold not what people already own.
The king (meaning preferred brand not most commonly sold) of unenlightened folks brand of flashlights, Maglite, has already transitioned.
Even Walmart and Home Depot are more or less replacing their AA/AAA powered lights with inventory of16340 and 18650 powered lights. REI appears to have already done that.
The Olight S10 and S10r fit quite nicely on my husband's and my keychain and will fit quite nicely on my mother in law's keychain before Thanksgiving as a birthday present she asked for.
thedoc007
Flashlight Enthusiast
Either way, there is no way 18650 and 16430 own 90% of the market.
Transitioned to LED, yes, but not to lithium-ion. All Maglites that I am familiar with still use AA, AAA, C, or D batteries. NONE of them use 18650 or CR123/16340, as far as I know.
REI definitely has some lithium-ion lights, but they still sell AA/AAA/C/D lights too. Walmart (at least in my area) has a few CR123 lights in the sporting goods section, but in the lighting aisle, most of the lights are still the AA/AAA/C/D. I'm not trying to say that the chemistries/sizes you name aren't growing in popularity, but your claim that they own 90% of the market is definitely a gross exaggeration.
Plenty of cheaper, less than desirable lights still remain on Walmart's and even Home Depot's shelves but most often are excess inventory that hasn't sold. Perhaps the percentage of new lights being produced for the mainstream market hasn't reached 90% but it isn't a gross exaggeration either.
Race to the bottom economics has impeded the clearance of non-lithium-ion battery powered lights inventory but they are what people end up wanting when they go to the stores and see what's out there. It's kind of difficult buying lithium-ion powered lights working for near minimum wage.
Maglite's Mag Tac Series uses 16340 batteries and are the better Maglite lights.
thedoc007
Flashlight Enthusiast
Cool, thanks. Hadn't seen those before.
I just realized we are derailing the thread. I'll refrain from further comments on the market issue.
Please create another thread and I'll continue the conversation with you there. Please link me to it.
You miss the point that weight is a proxy for size. if it's got more energy by weight, it has more energy by size as well (this makes some assumptions about chemistry, but as far as I know these assumptions are correct). The absolute size or weight might not fit your needs, but that has nothing to do with OP's question, which I note there are still exactly zero posts in this thread attempting to answer.
The further problem with size volume is do you measure absolute volume or, as per your stated preferences, do you measure length and ignore diameter? Or vice-versa? Hence my point that weight is a single, simple measurement that gets you in the right ballpark and you can nitpick about form-factors from there if you want (like whether 14500 or 16340 is better, given they have the same energy density but are different shapes).
thedoc007
Flashlight Enthusiast
No, I didn't miss the point. I simply don't care about weight (within reason), and as you alluded to, different chemistries have different weights, for the same volume. So I don't think it does make a good proxy. A matter of opinion.
I also never said I would ignore diameter, and measure length only. No idea where you got that...the very quote you used discusses both diameter (width) and length.
Nor do I understand why you don't think anyone has answered the OP's questions. He asked two things...summarizing...if there was a battery type that was more energy dense than others, and what type of light we would prefer if given the choice of any size cell. Both questions have been answered, you may disagree, but I don't see how you can call all the posts up to this point irrelevant.
To me, it is pretty simple. No complicated math need be involved, although if the OP requests it, we could certainly go that route also. But without getting into detailed volumetric calculations...
One 18650 has about the same capacity as four AA batteries. Obviously four AA take up more room than one 18650, but they don't give you more energy.
One 18650 has about the same capacity as five 16340s, or two CR123. Two CR123 are as close as you can get (slightly smaller than a single 18650, but also contain slightly less energy. Also MUCH more expensive, if used regularly, and more wasteful, and greater likelihood of problems (reverse charging isn't an issue with one 18650, but it is with two CR123 in series.)
Pick any size you want, for standard cylindrical cells, and you'll find 18650/26650 offer the best performance for their volume. That's why my choice would be one of those two types. 18650 for an EDC light, and 26650 if I want a single cell to give me very high performance, or long runtime.
Of course, even this is an oversimplification, because you can also get plenty of lights that use multiple cells. Two 26650s, or three 18650s? Similar capacity, different form factor. But either one could be smaller than an AA light with similar capacity. Or given two lights of the same size, the one using 18650/26650 would have more capacity than the one using AAs.
(AA used merely as an example...you can fill in whatever cell size you like, and the answer will change only in degree.)
Yes, I am (as I already said) making an assumption about density, namely that there isn't a compound that has both a high energy density and a high mass density. Lithium chemistries are all lightweight and have the highest energy densities. Of course it's possible there will be some small difference between certain lithium chemistries where you can choose between the smallest volume or the lowest weight for the same energy density, but AFAIK there isn't enough in it to be worth caring about.
Of course, whether we choose weight or volume is largely irrelevant as long as we pick one or do both. That's manageable. What's unmanageable and full of personal opinions that will never agree is "size", meaning length or diameter or some combination of these that isn't the volume. Given 16340 and 14500 both have max capacities of 750mAh, it's down to personal opinion whether you prefer shorter and fatter or longer and thinner. They both have the same energy capacity and approximately the same weight and volume too. What is perhaps interesting is that the 14500 looks a lot bigger, which is because volume is directly proportional to the length of a cylinder, but proportional to the square of the diameter. Looks can be deceiving though.
I did just weigh a 14500 and 16340 and found the 16340 to be marginally lighter (and therefore of slightly lesser volume), although they were different makes so that's maybe not a 100% fair test. Plus it has a sample size of 1. I would argue that these cells are essentially indistinguishable in either volume, weight or capacity, but are considerably different in terms of length and diameter.
Since nobody else seems interested in doing it, I weighed a few cells. Here are the results:
16340: 750 mAh @ 19.0g = 39.5 mAh/g
18650: 3400 mAh @ 47.4g = 71.7 mAh/g
CR123A: 1300 mAh @ 16.4g = 79.8 mAh/g
Therefore, perhaps surprisingly, the winner is the CR123A primary with the 18650 as runner up. I'm a bit surprised as I thought the 18650 would dominate. There are also 1500mAh CR123As but I don't know if those would be heavier - it's possible those have an even higher energy density, although it's also possible the capacity is overstated. Of course, primaries have a lot of disadvantages, as already noted. What is striking about these numbers is that, despite being the same chemistry, an 18650 has almost double the energy density of a 16340 or 14500.
For completeness, I would be interested in the figures for a 26650 for comparison, but I don't have one to weigh. I did try googling for specs, but I don't think manufacturers generally bother publishing the weight of their cells.
Of course there is one further practical consideration which is that once you have your chosen cell, you need a light to put it in. One thing I have noticed is that while there are quite a few small AA/14500 and CR123/16340 sized lights, most 18650 lights are a lot bigger than they need to be. This means you may find much bigger differences in overall system efficiency when you start looking at not just the cell, but the entire light (the cell, the body, the circuitry, the LED). Also, while smaller lights may be more size-efficient in terms of design and construction, they may be less efficient overall because of the relatively fixed overheads (size of reflector, switch, circuitry, etc.)
For comparison, I weighed a couple of lights as well (batteries installed). Here are those results:
Nitecore P12 + 3400 mAh 18650 @ 137.4g = 24.8 mAh/g
EagleTac D25C Clicky Ti + 750 mAh 16340 @ 57.1g = 13.14 mAh/g
EagleTac D25A Clicky Ti + 750 mAh 14500 @ 48.6g = 15.4 mAh/g
Of course once we are talking about whole lights, weight isn't really a good proxy for volume anymore, but it's still a simple-yet-useful guide to overall size-efficiency. It would be even more useful if we replaced the mAh rating of the battery with the lumen-hours rating of the light, but that throws up even more issues about how to fairly measure lumen-hours across different output levels, different types of regulation, PWM vs direct drive, and so on.
Of course, whether we choose weight or volume is largely irrelevant as long as we pick one or do both. That's manageable. What's unmanageable and full of personal opinions that will never agree is "size", meaning length or diameter or some combination of these that isn't the volume. Given 16340 and 14500 both have max capacities of 750mAh, it's down to personal opinion whether you prefer shorter and fatter or longer and thinner. They both have the same energy capacity and approximately the same weight and volume too. What is perhaps interesting is that the 14500 looks a lot bigger, which is because volume is directly proportional to the length of a cylinder, but proportional to the square of the diameter. Looks can be deceiving though.
I did just weigh a 14500 and 16340 and found the 16340 to be marginally lighter (and therefore of slightly lesser volume), although they were different makes so that's maybe not a 100% fair test. Plus it has a sample size of 1. I would argue that these cells are essentially indistinguishable in either volume, weight or capacity, but are considerably different in terms of length and diameter.
Since nobody else seems interested in doing it, I weighed a few cells. Here are the results:
16340: 750 mAh @ 19.0g = 39.5 mAh/g
18650: 3400 mAh @ 47.4g = 71.7 mAh/g
CR123A: 1300 mAh @ 16.4g = 79.8 mAh/g
Therefore, perhaps surprisingly, the winner is the CR123A primary with the 18650 as runner up. I'm a bit surprised as I thought the 18650 would dominate. There are also 1500mAh CR123As but I don't know if those would be heavier - it's possible those have an even higher energy density, although it's also possible the capacity is overstated. Of course, primaries have a lot of disadvantages, as already noted. What is striking about these numbers is that, despite being the same chemistry, an 18650 has almost double the energy density of a 16340 or 14500.
For completeness, I would be interested in the figures for a 26650 for comparison, but I don't have one to weigh. I did try googling for specs, but I don't think manufacturers generally bother publishing the weight of their cells.
Of course there is one further practical consideration which is that once you have your chosen cell, you need a light to put it in. One thing I have noticed is that while there are quite a few small AA/14500 and CR123/16340 sized lights, most 18650 lights are a lot bigger than they need to be. This means you may find much bigger differences in overall system efficiency when you start looking at not just the cell, but the entire light (the cell, the body, the circuitry, the LED). Also, while smaller lights may be more size-efficient in terms of design and construction, they may be less efficient overall because of the relatively fixed overheads (size of reflector, switch, circuitry, etc.)
For comparison, I weighed a couple of lights as well (batteries installed). Here are those results:
Nitecore P12 + 3400 mAh 18650 @ 137.4g = 24.8 mAh/g
EagleTac D25C Clicky Ti + 750 mAh 16340 @ 57.1g = 13.14 mAh/g
EagleTac D25A Clicky Ti + 750 mAh 14500 @ 48.6g = 15.4 mAh/g
Of course once we are talking about whole lights, weight isn't really a good proxy for volume anymore, but it's still a simple-yet-useful guide to overall size-efficiency. It would be even more useful if we replaced the mAh rating of the battery with the lumen-hours rating of the light, but that throws up even more issues about how to fairly measure lumen-hours across different output levels, different types of regulation, PWM vs direct drive, and so on.
HKJ
Flashaholic
A few comments:
16340 and 14500 do not have the same capacity, 14500 usual has higher capacity (Do not trust the values printed on the batteries).
CR123A may have a good specific energy, but I believe some low current batteries are even better.
To get numbers for weight, size, energy etc. look at my website.
16340 and 14500 do not have the same capacity, 14500 usual has higher capacity (Do not trust the values printed on the batteries).
CR123A may have a good specific energy, but I believe some low current batteries are even better.
To get numbers for weight, size, energy etc. look at my website.
For this comparison to be valid, you need to compare Watt Hours, not mAh. With the same voltage, Amp hours works, but the CR123A is a lower voltage battery, throwing off your comparison.
I was wondering how long it would take for someone to notice that, I thought I'd gotten away with it
- I just picked amp-hours because those figures are always given and my original point was always to pick the thing that is easiest to calculate, as a proxy for other (hopefully equivalent) measures. Good point about the error though, I hadn't thought about the fact it could throw the figures off enough to make a difference, but clearly I was wrong about that.As it happens, it turns out both the lithium ion cells state their watt-hours rating on the side, so here are the corrected figures for those:
16340: 2.8 Wh @ 19.0g = 148 mWh/g
18650: 12.6 Wh @ 47.4g = 266 mWh/g
However, I don't know the rating for the CR123 that I weighed. It's a Surefire, if anyone happens to know. Or else weigh your own if you know it's rating and let's see if this pushes the 18650 back to the top. Here's an estimated calculation based on the watt-hours being exactly the mAh * (nominal voltage) / 1000, where nominal voltage is 3.0 in this case:
CR123A: 3.9 Wh @ 16.4g = 238 mWh/g
If that's the correct Wh for a Surefire CR123A then indeed it has a lower specific energy* than an 18650. At least according to my measurements: ymmv, no warranties express or implied, something something sample size, and so on.
* I suppose we should also use the correct term here since HKJ mentioned it; I always get these mixed up, or to be more accurate, I just prefer the term energy density even if it's the wrong one.
HKJ
Flashaholic
With primary cells there are a couple of problems when doing this type of calculations.
Look at this curve (16.5 gram):
The tell me at what current at what voltage that you want the specific energy at.
Then compare to a 18650 (48.1 gram):
At 1A:
CR123 down to 2.0 volt: 164mW/g
18650 down to 3 volt: 239mW/g
At 0.2A:
CR123 down to 2.0 volt: 230mW/g
18650 down to 3 volt: 251mW/g
Look at this curve (16.5 gram):
The tell me at what current at what voltage that you want the specific energy at.
Then compare to a 18650 (48.1 gram):
At 1A:
CR123 down to 2.0 volt: 164mW/g
18650 down to 3 volt: 239mW/g
At 0.2A:
CR123 down to 2.0 volt: 230mW/g
18650 down to 3 volt: 251mW/g
