Am wanting a 10A continuous 18650-21700 cell

Is there a cylindrical cell between 18650 and 21700 that would comfortably handle 10amps continuous with good cycle life (like 700+) (assuming between 3v min - 4.1v max ) that doesn't cost $10+ per cell ?

IMR battery Samsung 25r
https://www.imrbatteries.com/samsung-25r-18650-rechargeable-battery/

Another cell to possibly consider is the Sanyo ur18650nsx, nigh on identical performance and both a wee tad better then HE2.

Re are many that can supply 10 A continuous..
But, you omit to mention what capacity (Ah) you expect to need...and that cuts down your options considerably.

Why? just parallel your strings. . .

That Sanyo "NSX" does look good. Thanks for the tip.

john61ct said:

Why? just parallel your strings. . .

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I want as small a pack as possible so I will have a little room left over in my battery box. It's not a bike. It's an offroad scooter 36v and there just isn't a lot of space for controller and battery . I know if I use a cell rated for 10a max and I'm pulling 7amps per cell or more , it won't be lasting very long. That's why I want a cell that runs cool at 10 amps continuous. If I can build a pack that has close to 15AH and can handle that kind of load , I will be happy .

999zip999 said:

IMR battery Samsung 25r
https://www.imrbatteries.com/samsung-25r-18650-rechargeable-battery/

Click to expand...

That looks like a winner as well.

LG HG2
Samsung 30Q

Or if you can accept more sag, LG MJ1 works too.

That UR18650NSX looks pretty amazing in testing, unless there's something I'm missing. Doesn't break 35°c @ 20a

DjSpaceGhost said:

john61ct said:

Why? just parallel your strings. . .

Click to expand...

I want as small a pack as possible so I will have a little room left over in my battery box. It's not a bike. It's an offroad scooter 36v and there just isn't a lot of space for controller and battery . I know if I use a cell rated for 10a max and I'm pulling 7amps per cell or more , it won't be lasting very long. That's why I want a cell that runs cool at 10 amps continuous. If I can build a pack that has close to 15AH and can handle that kind of load , I will be happy .

Click to expand...

You are still not explaining what you want.
36v, 15 Ah pack...will have to have parallel cells...most likely 5 or 7p .
So why the 10a/cell requirement ?..do you expect to draw 50-70amps continuous ?

Hillhater said:

DjSpaceGhost said:

john61ct said:

Why? just parallel your strings. . .

Click to expand...

I want as small a pack as possible so I will have a little room left over in my battery box. It's not a bike. It's an offroad scooter 36v and there just isn't a lot of space for controller and battery . I know if I use a cell rated for 10a max and I'm pulling 7amps per cell or more , it won't be lasting very long. That's why I want a cell that runs cool at 10 amps continuous. If I can build a pack that has close to 15AH and can handle that kind of load , I will be happy .

Click to expand...

You are still not explaining what you want.
36v, 15 Ah pack...will have to have parallel cells...most likely 5 or 7p .
So why the 10a/cell requirement ?..do you expect to draw 50-70amps continuous ?

Click to expand...

For now it will be a 35amp controller - 36v 15AH( or close as possible to that) I expect to need around 6P to get the capacity and durability I want. I don't require 10a per cell, I just want a battery that will handle the 6-7a loads on a constant basis without getting hot and I want to have it last for 700+ cycles if possible. I realize I may be off on my approach, but from the research I've done, I have become convinced that a cell that can handle 10amps per cell for long stretches without getting much beyond 30°c will get me there. I asked the question so vaguely because I wanted educated opinions of what cells didn't break a sweat with 10amps constantly without getting into specifics of pack build and all. I see TONS of manufacturer claims , but I've seen a lot of real world experiences from posters here that tell a different story , such as X battery has 3500mah or 15a continuous discharge, BUT due to high IR after X cycles , it's voltage sag is like an 80year old man carrying a 50lb bag of rocks . I'm making stats up, but you get the point I'm sure.

Another criteria also depends on price/performance, are you after the best priced cell or want the best mah per cell.
Obviously 30Q/ HG2 will give more mah/range but at a higher price point.
Compared to 25R/NSX, cells with more mah can be as much as 30- 55% dearer ( based on EU Nkon pricing).

My understanding - gurus please confirm?

"Quality" does not have one dimension. Focusing excessively on c-rate as the only indicator of quality starts to take you away from longevity.

Lipo batteries that optimize for high current output (lower over-temp) sacrifice designed mAh capacity (and longevity) to get there.

Those models focused on mAh capacity will get hotter at high-C discharge rates.

The real way to get longevity is to lower the c-rate, either in usage patterns or by going to a bigger Ah pack size (more strings).

To me, that means if longevity is important, go for as big Ah a bank as possible, and select cells based on Quality reputation whose tested c-rate are " just enough " to meet your usage needs.

This is long winded and rambling so ignore it if you don't have time and patience .

Sorry, my communication skills aren't the best. I have a hard time expressing what I am really wanting to say.
I didn't want to ask ; is 30Q better than Sanyo NSX or GA because then I get answers biased toward those 3 cells . I should have asked ; what are the best cells at 7ish amps continuous for a balance of cell life and output? Because I was then more likely to get a broader range of suggestions and maybe something I was unaware of or hadn't considered. I realize the greater amount of parallels you have reduces the amp load for each added P cell , but each connection adds to the overall resistance of the pack . That and the quality of the connections, so that's why I focused on individual cell performance. Price matters , but longevity and performance are the top two criteria . I know lithium phosphate is a no brainer for long cycle life, but price becomes more of an issue there.

I can build a 36s5P of 30Q for $212.50 from IMRbatteries. That gives me around 15AH or 75amps overall . After looking at this test ( https://lygte-info.dk/review/batteries2012/Samsung%20INR18650-30Q%203000mAh%20%28Pink%29%20UK.html ) ,going by rated max continuous amp drain , this battery chugs along around 10 minutes per cell runtime at 100% DoD(4.2v->2.8v ) @15A . At that amp rate , it looks like a 5p string would have around 13.25 AH . It would also be nudging 50°c . I know the completed pack's resistance, temperature ,chemistry quirks and my vehicle's variables will affect the overall results , but I am just comparing the results per cell by this one test before considering those outside influences.
https://www.imrbatteries.com/samsung-30q-18650-3000mah-15a-flat-top-battery/

Now in the same scenario , the NSX ( https://lygte-info.dk/review/batteries2012/Sanyo%20UR18650NSX%202600mAh%20(Red)%20UK.html) runs for 8-9 minutes at the same 15a rate , but is at around 28°c when the test is stopped. I realize that the rated capacity is higher on the 30q , but that's a major difference in operating temp . A pretty smart guy that happened to be the key in inventing NMC chemistry has stated that temperature is probably the most important factor in cycle life . A comparable pack of those 36s6p would cost $210 plus have a few more AH . 2300x6 = 13.8AH (@15a) https://www.imrbatteries.com/sanyo-ur18650nsx-2600mah-20a-flat-top-battery/

The NCR18650GA results are : @15a the test was stopped short due to over temperature limit. I was almost sold on this battery in the beginning until I saw this . Considering I won't be draining 15amps per cell , I looked at the temp @7a and it was around 30-32°c , which is fine obviously, but that is at 7 amps. The NSX is operating in that temp range at 15-20a ! hrm.... So back to the original point of this post; clearly the GA is perfectly capable of handling 7a continuous , as are several other batteries, but wouldn't a battery that doesn't break a sweat at 20amps be more likely to last longer than one that can't stay in a safe temperature at 15 ? That was basically why I was insisting on the 10amp parameter . Is it cut and dry , that for my uses, the UR18650NSX the best option? Or are there factors relative to individual cells that I'm not seeing? I don't want a 20 or 21AH pack that falls on it's face in 300 cycles or sags hard on anything over 5amps when I could get 800 from a 13.8 AH pack that doesn't lose 20% of it's capacity in the first 200 cycles . Sorry for the long winded babble . Basically , for a 60lb/27kg machine without battery , what are the best options for a 35 amp controller , 36 volt/15AH or so ,150lb rider, mostly level pavement riding, 32cm x 17cm battery box , and under $275 USD total . I want to build it myself or come from a reputable source in the US so I won't have expensive shipping issues if it shows up DoA . I've had the suggestions of prismatic pouches (which sound like good options) , 25R , 30Q, UR18650NSX,HG2, MJ1 and HE2. Those all look like great options. Is there a best for my envelope , or just choose any one of those because they're all equally capable ? (yes I am mentally ill and borderline obsessive over hair splitting details)

Babble babble. After you make the pack and have it for 5 years and 800 cycles you will find out. It takes hard data. Do you have a spot welder ?

DjSpaceGhost said:

......but wouldn't a battery that doesn't break a sweat at 20amps be more likely to last longer than one that can't stay in a safe temperature at 15 ? .....

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In short ...NO !.. it may be one indicator, but there are many other factors at play dictating cycle life.
A cell that can stay cool at high discharge levels, would typically be a high power design with a chemistry formulated to prioritise power over many other factors ..such as energy density. Typically those chemistry formulations do not have great cycle life.
As you are discovering, cell choice is a tricky compromise of criteria, which you have to optimise to suit your specific application and priorities. :?

Hillhater said:

DjSpaceGhost said:

......but wouldn't a battery that doesn't break a sweat at 20amps be more likely to last longer than one that can't stay in a safe temperature at 15 ? .....

Click to expand...

In short ...NO !.. it may be one indicator, but there are many other factors at play dictating cycle life.
A cell that can stay cool at high discharge levels, would typically be a high power design with a chemistry formulated to prioritise power over many other factors ..such as energy density. Typically those chemistry formulations do not have great cycle life.
As you are discovering, cell choice is a tricky compromise of criteria, which you have to optimise to suit your specific application and priorities. :?

Click to expand...

THAT is helpful. Thank you . I'm slowly starting to catch a little here and there.

EDIT - I replied a day after I read the thread and forgot that this battery is very space constrained on a scooter so the below doesn't apply in this case but I'll leave it anyway.


Choosing a suitable cell is certainly important, but if you want good cycle life then the other very important factor is;

Build a big enough battery

Max SoC is a huge factor and some cells may achieve 3x the cycle life simply by charging to 4.05 instead of 4.2

Obviously if charging to 85% - 90% you need some extra cells to get the same range, that might mean 1 or 2P extra so more cost and weight/size. The cost part is a no-brainer as 1P extra is like getting a free battery or two in the future.

Note that this extra cycle life is based on testing of single cells. In a battery the extra P groups give you the additional benefit of lower current draw per group further reducing aging & sag effects, and opening up options for higher capacity / lower rate / cheaper cells.

To summarize; P good. Add more P.

Attempt #2.

Since a big battery isn't an option I'll suggest something I'm doing with some 2P short range batteries for my current bike project.

Have more batteries.

If it's possible have a way to dismount the battery easily & have 2 or more (I'll have 5, shared with my GF). Then it's feasible to charge to 90% yet still have more range by carrying a spare when needed and there is always a full one waiting on the charger.

Small batteries are cheap. Make more so you can be kind to them.

The real key to cell longevity, even more so than lowering the C rate (bigger pack) is not drawing down all the way to the BMS cutoff point voltage.

Lowest I'd go is 3V, but that is low single digit SoC.

80% DoD or even less is better.

Swapping out multiple packs, if practical, will enable such a strategy.

That's actually not a bad idea... fewer cells per pack to cause problems too.