Surprising battery results 26650 vs 18650

I just did some draw tests on a KD C8 XML and the F13 Xm-L2 clone OL recommended. I was quite surprised that the 26650 preformed this much better than 18650 cells.
The batteries were all charged to 4.18-4.2v and had been off the charger for a few hours.
I used my Opus charger to check battery resistance, all the 18650 tested between 105-140. The 26650 tested at 80 (Maybe this why they pulled more?)
The 26650’s and the Panasonic NCR18650b are brand new, and who know about the laptop pulls. I assumed since I choose 18650’s with close resistance they should perform similarly, and for the most part I’d say they did.
I really didn’t expect the 26650 to pull that much more amps ~ 20% I would think that is quite significant. I found this interesting, as I always thought the only advantage to 26650 was longer run times.
|Battery|XML direct drive|XM-L2 direct drive|
|MKE 26620|3.18A|3.38A|
|IMREN |3.17A|3.37A|
|Panasonic NCR18650B |2.49A |2.50A|
|Panasonic CGR18650 laptop pull|2.59A|2.51A|
|Sony US18650GR laptop pull|2.52A|2.58A|
|Unknown 18650 |2.58A | 2.60A |
|Samsung blue top laptop pull|2.29A | 2.35A|

Other than being “too physically big” for some applications, I believe that 26650’s are more useful and perform better and thus, will become more popular over the next few years. I look for lights that use those larger batteries and more and more manufacturers are selling flashlights that can use them.

The 26650's generally have less voltage sag which can also lead to higher amps.


Isnt the MNKE a high perf battery so an 18650 such Samsung 25R, LG HE2 or Sony VTC5 would be more appropriate for comparison?

I thought the conventional wisdom was that a 26650 in single cell, clearly had a cap advantage, but when it came down to it, pound for pound, no 26650 compares to a decent 18650. I thought that was the wish, that makers would start improving the 26650 so it had the benefits of the 18650 in the capacity of 26650?

Although, to an amateur like myself, what Gary says above makes sense. More capacity to supply the amps, means it takes longer for v sag to be an issue, provided the amps are within reason. But that was the thing, the C rate of 26650 does not compare to decent hi-perf 18650s?

A 26650 is slightly more than twice the volume of an 18650 but doesn’t match this in capacity. Since the casings are the same thickness this favors the larger cell even more(higher percentage of volume for storage medium). It would be nice to see cells that took advantage of this.

My hd2010 worked great with all 18650s; I put in a King Kong 26650, and fried it. So there is more than a mere capacity difference between the two.

I thought the Panasonic cell I used was also considered a high performance cell. Nor did I think the high draw cells made a difference until you started trying pull high amps say over 4+ amps. Again those were only my assumption, it appears that is not the case.

Given batteries that are made decently (not crap) a larger volume without significantly increasing the capacity should result in lower resistance and higher potential output. You can see that in the IR of the 26650 is notably less than the 18650, along with the ability to support the output.

If you parallel connect a bunch of similar batteries together the voltage stays the same, capacity is additive, and the ability to sustain voltage goes up significantly. That’s basically what you are seeing here.

If you increase the capacity of the 26650 significantly > you will decrease the performance. Right now you can’t have both.

That being said I agree that a larger cell could supply a higher current for only slightly longer but what about similar amp draw but much higher capacity. Since we have 3400mAhr 18650’s that are good for 4A shouldn’t we be able to have 7Ahr 26650’s good for 4A?

A123 - 26650 LiFe are good for ~70A (by spec, if you believe that).
Another sheet says 50A.
I know RC flyers that do use them and for sure are quite comfortable with 30A output.
I’ve used the 1100mA 18650 cells and compared to ‘average’ 18650 they kick butt, but the capacity is pretty low. They are way more robust, way more.

I don’t know diddly about the limitations associated with cell size, plate surface area, chemical and electrolyte density, and electron migration distance to even hazard a guess. Not everything simply scales ‘up’.
I would think that if the 26650 was overall a much better battery the Tesla would be loaded with them. OTOH maybe there is simply not enough development and manufacturing capacity for large scale output. Most of us have a LOT of AA cells and not nearly as many D’s.

Sometimes, even if a 26650 was better, it would be less efficient to use them due to the wasted space between larger cells say in a Tesla. ie: the total area of the battery compartment, is less full of charged material than if a thinner battery was used. In other words, the ratio of charged material to air, is lower with the fatter cells (more air, less material).

Or is there some law of gadgetry and electronics or maths that makes that impossible?

I wish someone here would review them and explain thier qualities and practical applications. The 18650s don’t last long enough for even short bike rides.

Are HKJs battery reviews not enough? He has reviewed, and charted a lot of batteries.

Where are you sourcing your batteries?
Define short bike ride?

Im not sure how a 26650 fried your HD2010, Im pretty sure plenty of people run them with 26650 in them, the KK being a particular favourite for 26650. I dont recall reading a thread warning not to use the 26650 in them. Although, its possible most HD2010s from this site were modified as that was the purpose of a GB and series of videos to mod them by OldLumens. The HD2010 did however come in many incarnations, some not so great. Its possible yours was one of those. Good opportunity to pull it down, watch the clips, and make it function again, brighter.

Anyone used these before? A friend of mine said there were good but idk much about batteries.

UltraFire? Do you play craps?

Tell folks what country youre from? and
What you want to use them in?

and you’ll likely get a some suggestions of the right cell for the job, rather than just peoples favourite battery. Although maybe not here in this thread, another thread might be more suitable… one of the many about similar enough questions to the one youve asked.

I too have noticed that my lights perform better (higher output) when using 26650 batteries compared with 18650’s.
I can’t imagine why, and I’m quite clueless about things electrical/electronic but I know this to be true. I’ve tested a few
of my (26650) lights, and they all respond likewise.

I’ve seen the arguments about stacking different size cells in a volume but they didn’t take into account the space and weight taken up by the battery case. A 26650 has more than twice the volume of an 18650 but the case is only 26/18 ~ 1 1/2 times as large or heavy. It may or may not still require more volume than an 18650 but a Tesla could shed a significant amount of weight if 26650’s had the capacity their volume suggests and for an EV weight is critical. I think a Tesla uses the best cells they can and right now on a power to weight ratio 18650’s are still tops. Maybe the plant they are building will crank out a better 26650’s, we can always hope.

The reason is that the battery is bigger. That is why it can deliver more current, all other things equal. But as has been said above, a 26650 has twice the volume of a 18650, but not twice the capacity. I assume that this is because many more 18650 are used, and the competition stiffer, leads to more product development. 26650 may benefit from developments as well, but not as fast.

However I also suspect that there is more shenanigans going on regarding junk 18650 with fake specs. That may also be a reason why you experience that 26650 is better. Maybe you compare a junk 18650 battery with a descent 26650?

Your friend doesn’t know squat about batteries then. Complete rubbish.
I had one that came with a light and it had 600mA and went down hill from there fast. All the **fire batteries are junk.

The million dollar question. Is the reason why 22650s are not nearly as popular as 18650s is because of their form factor they are too big?
22650s are electronically inferior
22650s are not politically and financially as feasible because 18650s dominated the laptop market and to change over doesn’t make financial sense.