How many people use 26650's?

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I understand they're a bit less in wh/kg, but some of these cells have a pretty good c-rate:

https://liionwholesale.com/collections/batteries/products/efest-imr-26650-4200mah-50a-li-mn-flat-top-batteries-wholesale-lot?variant=1074703040

"These are the new version of the Efest IMR 4200 mAh battery. They will really pump out the high current at 35A continuous, 50A pulse, and 4200mAh total capacity. These efest 26650 batteries have been awesome in our testing, being able to handle some serious current while going at it for a long time.

Size: 26650 (26.22mm diameter x 65.11mm long)
Note these seem to be ~67mm long despite the Efest spec, make sure your device has the space for them
Type: Li-Mn IMR (Rechargeable)
Rated Capacity: 4200mAh
Max Discharge Current (Continuous): 35A
Max Discharge Current (Pulse): 50A
Voltage: 3.7V
Protected: No
Style: Flat Top
Weight: 100g
Initial Impedance: 13Ω (plus or minus 2Ω)
Color: Purple
Rated storage temperature: 20-60 C
"
 
Never trust the C-rate from companies like efest. It's all just marketing and made up numbers based off no actual testing or standard.
 
It looks like the wholesaler is doing the testing. If it says 35 amp continuous, then I'd probably trust it at 17~20 amp, right?
 
redilast said:
Never trust the C-rate from companies like efest. It's all just marketing and made up numbers based off no actual testing or standard.

i used to be an Efest dealer until they sent me these (e)festering 16650's. had holes in them and leaked :evil: you can't trust those people

5upbk5E.jpg
 
@Overclocker: Looks kinda like they tore them off spotwelded packs. Probably recycled garbage like ultrafire and similar.


@OP: They're probably 67mm long because they hid the actual ends of the cell under fake caps held on by the new fake-label heatshrink over them. ;)
 
Whoa, look at that. So, there aren't any reliable 26650's that have a very safe 4~5C continuous? It just seems like a pack with fewer cells means fewer pieces to assemble and worry about. You can't stack them as densely as smaller cylinders, but if it can deliver decent amps like a multistar brick, then why isn't everyone using them?
 
The two reasons I usually find that "everyone isn't using" something are either

--high cost (for the stuff that's actually really good but not in widespread use),

or

--it isn't *worth* using, often because it's recycled garbage (literally) like Ultrafire or other *fire cells. The vendor above appears no different from the stuff I see when searching on their name on the web.

One search:
https://www.google.com/search?q=Efest&ie=utf-8&oe=utf-8#q=Efest+garbage&*
just looking up the vendor name finds a zillion things, many unrelated, or just ads or resellers, but the above has some more useful info.

hypertoric_amplituhedron said:
It looks like the wholesaler is doing the testing. If it says 35 amp continuous, then I'd probably trust it at 17~20 amp, right?
Unless you can find an independent tester that's already trusted that has verified that, you can't really trust any numbers from any seller. Their job is to sell things...and they'll usually do it by any means necessary, including lies, deception, misleading wording, pics of stuff they dont' even have, etc.

There's a few honest ones out there...but not enough to trust any seller until their info is verified by someone you know has done the testing right and verified other stuff too.

Or until you're willing to potentially waste the money and time doing the testing yourself.
 
hypertoric_amplituhedron said:
Whoa, look at that. So, there aren't any reliable 26650's that have a very safe 4~5C continuous? It just seems like a pack with fewer cells means fewer pieces to assemble and worry about. You can't stack them as densely as smaller cylinders, but if it can deliver decent amps like a multistar brick, then why isn't everyone using them?

It's simply not a popular form factor, so there aren't a lot of good options. I'm not aware of any 26650 that's not dramatically outclassed by the latest generations of 18650's. Samsung 30Q are a fantastic all rounder, power density is awesome, lifespan appears to be excellent and they're cheap.
 
There is no reason to use cells produced by no-name manufacturers with little or no safety compliance UL/UN testing etc. In the past I have used MNKE IMR 26650's, but after a year of use, even cells brand new in storage at 50% SOC doubled in IR. Stuff like this is common for no-name cells. The quality just isn't there. Cost wise you will almost always be better off with brand name cells when you factory in the life of the cell.

There is no big brand name manufacturer that I'm aware of that is currently even making 26650 3.7v cells. Sony and Panasonic and MOLI used to make them but have discontinued this format. Moving forward, 20700, and 21700 is probably going to be the format of the future for eBikes. But it will take a while for the cost to drop and production to ramp up to compete with 18650.
 
eTrike said:
A123 cells come in 26650. I've used/abused the same cells for 7+ years :) Fwiw, for heat dissipation and mechanical strength 18650s are better.
Yes eTrike , the A123 26650 is an excellent cell with high power potential , safe, and long life cycle reported from many professional users (drag racers , etc) but , like other quality cells in this size .(.Saft, K2 ?) , they have a major dissadvantage for ebikes and that is their Energy density is about 50% of the good 18650 NCR cells
Effectively that means for any particular Ah capacity a 26650 pack will be double the weight of a comparable Ah pack built from good 18650 cells...and physically much bigger.
 
I know Sony has good rep on their 26650 batteries. Sony SE US26650VT has high C rate but low capacity, like 2600 mAh or something. Iirc it will do 50A discharge no prob but if you keep it around 20 A you have almost no eccessive energy drop. When I looked for those they where hard to come by, and price varied a lot indicating at least a few knock offs, fakes and possible dangerous re wrapped cheap cells in Sony clothing. If you got room/real estate a bigger pack will compensate for the lower mah of each cell.

Maybe someone has tested and run these cells can fill you in on the details?
 
I'll second A123 LiFePO4 26650 cells, a bit pricey, but a quality battery with just about the highest discharge rate you can find.
 
I was just looking at a123batteries and they looked good.
https://www.a123batteries.com/product-p/anr26650m1-b.htm
Here's the data sheet too.
http://www.a123systems.com/Collateral/Documents/English-US/A123%20Systems%20ANR26650%20Data%20Sheet.pdf
The biggest disadvantage I see if I am not mistaken is the life cycles of the batteries. Over a 1,000 for 18650's and less than a 1,000 for 26650's.
 
animalss2 said:
I was just looking at a123batteries and they looked good.
https://www.a123batteries.com/product-p/anr26650m1-b.htm
Here's the data sheet too.
http://www.a123systems.com/Collateral/Documents/English-US/A123%20Systems%20ANR26650%20Data%20Sheet.pdf
The biggest disadvantage I see if I am not mistaken is the life cycles of the batteries. Over a 1,000 for 18650's and less than a 1,000 for 26650's.

They were good - about 8 years ago. Cycle life difference is largely irrelevant beyond a few hundred for our purposes. If you're building a decent sized ebike pack 1000+ cycles will equate to 60,000km or more. Quite simply by the time you've covered even half that you'll be able to build a pack with 50% more energy or take up a third less space/weight based on the constant iterative improvements of cells. 26650's are a dead form factor. Buy the latest developments, those are currently in 18650 but will soon be moving to 20700. Replace every three years or when you feel the need for more. You'll be a lot happier a lot more of the time than committing far too much money for already old technology that only becomes more dated.
 
animalss2 said:
I was just looking at a123batteries and they looked good.
https://www.a123batteries.com/product-p/anr26650m1-b.htm
Here's the data sheet too.
http://www.a123systems.com/Collateral/Documents/English-US/A123%20Systems%20ANR26650%20Data%20Sheet.pdf
The biggest disadvantage I see if I am not mistaken is the life cycles of the batteries. Over a 1,000 for 18650's and less than a 1,000 for 26650's.
:shock: ? How on earth is 1000+ cycles AT 10C... A disadvantage ??
You are not reading or understanding that data sheet correctly.
I challenge you (or anyone) to find a commercial cylindrical cell with better charge /discharge performance and a cycle life that exceeds 1000 .!
 
A123 is a step ahead heavy but great. Great. 999cycles till tomorrow and then 1,000 cycles at low amp demands. But 1,000cycles.
It's about quality.
 
999zip999 said:
A123 is a step ahead heavy but great. Great. 999cycles till tomorrow and then 1,000 cycles at low amp demands. But 1,000cycles.
It's about quality.
Its not just quality, but also its a impressive capability for any cell chemistry,...new or old.
I have no idea what you were trying to say in the rest of that post. :? .....
A123s spec is more than 1000 cycles at 10C (26 A)
 
Proven cycles in real world not just on paper. It's taken over 4yrs to reach over 1,000 cycles. Meaning quality is the ticket. Using a 10amp 18650 at 10amps and see how long it last.
 
The Battery Doctor said:
I have found genuine 5000 mah 26650 battery cells from china. They are about €50 each so it the price would be better you would only need 20 to build a standard 36V10ah pack and then they would be comparable. I accidentally bought a bunch of 26650 holder so if someone in europe are interested, let me know!

Why would I ever buy a €50 battery with 5000 mAh? For the same 50€ I could get 10 Sony VTC 6 with 3120 mAh and 30 A discharge. A total of 31200 mAh compared to the 26650 5000 mAh. For the same price I get 6 times the mAh. Or even get 7 of the new Sanyo 20700 A or B cells, 7 x 4250 mAh = 29 750 mAh. Or 6 of the A cells @3300 mAh for 19 800 mAh. But with 3 times the discharge over the B cells and 4 times the mAh of the 26650. Or what about the now "aging" 18650 hi C rate cells like from Lg H....someting etc. Those should have seen a fair price drop by now?

By the time I've added enough 18650 or 20700 cells to make a usable battery pack I got plenty of C rate for even high powered e-bike. And by using well known brand cells I know that rating is in fact spot on and not some marketing BS. Not saying that 26650 cells are feaks, but unless they are from known source and from a well known brand chances are you are burning your money on fakes, rewrapped's or quality control rejects.
 
Yah know... so far on ES "Search found 2071 matches: +26650"... BUT very few thread SUBJECTS re the 26650's? So just wished to add this article from June (already posted on ES, but again, "buried" in another thread...)

The New 21700 format Lithium Cells in 2017:
https://www.electricbike.com/new-21700-cells/

Includes:
Cells21700_7-1.png

The 26650 cell is on the left, a 20700 is in the center, and a common 18650 is on the right. 26mm diameter is very close to one inch, which is the diameter of a US quarter coin.
 
If you are seriously thinking about buying an uncommon cell, especially from a sketchy vendor...maybe buy three, then thoroughly test them to see the actual mAh capcity, and then see how hot they get when you draw the amount of max amps you plan to pull (for thirty seconds). If it is over 140F, then...no. If it is 110F-140F, then...maybe?

Anything below 110F during max amp-draw is a good design goal. Warm enough that you can feel that it is warm with just your hand (when drawing max amps), but cool enough you can hold your hand on it continuously. [104F / 40C is a very common recommended temperature for a "hot tub"]

Unless you are racing. If you are racing? Beat the crap out of them, and then split the cells apart from the pack and use them for flashlights, or a laptop booster pack..
 
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