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18650 or pouch
#1
I’m in the process of building a battery for an Ebike project and I came across a reasonably priced pouch on Aliexpress

There seems to be a ton of work building a 10p20s in 18650 batteries, although they do have other benefits
With pouches, I liked the option of a 1p20s config, using 3.7v 29ah batteries, 84amp continuous, 140amp max with BMS
Shenzhen Cozemate is the company selling them and I was wondering if anyone else had had dealings with them and/ or their batteries?

Apart from the obvious physical cell protection and heat dispersion aspects, are there any other considerations I’m not factoring in, or should be thinking about?
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#2
you mean you have 20 strings connected in parallel (with a bms for each string?)
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#3
Vibration? EBike use is obviously a physically rough environment - not saying pouch or 18650 is better, but loose pouchs might have issues?
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#4
20 strings? 10 cells in parallel, and 20 of those in series to give 72v
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#5
A "string" is a term used to describe multiple cells in series connection. For more information and terminology, please read the FAQ located on the main page.

(12-28-2019, 12:40 AM)BattMan Wrote: There seems to be a ton of work building a 10p20s in 18650 batteries, although they do have other benefits

Here you say 10p20s, which means 10 strings of 20 cells connected in parallel. ie, a single string would be 20 cells longer, but only 1 cell in each section. Then 10 of these connected at the ends in parallel.
Now, if you mean having 10p packs connected in parallel, then have 20 of these packs in series, then this is 20s10p. Order makes a difference. Again, please read the FAQ for more information

(12-28-2019, 12:40 AM)BattMan Wrote: With pouches, I liked the option of a 1p20s config, using 3.7v 29ah batteries, 84amp continuous, 140amp max with BMS

And with this here, 1p20s, is another reason why it sounds like you mean 10 strings of 20 cells. You said "1p". Can be very confusing if you swap terms and mean 10 packs connected in series.
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#6
I don't know if this applies in your case - but one difference between pouch and 18650 is that 18650 has metal containers to 'rigidly' hold the guts of the battery.  For pouch, I believe you need to build a container to keep pressure so they won't expand.  I could be wrong, but that's what I've read on several occasions..   someone may weigh in on this to refute or confirm Smile.
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#7
Yes, if they don't have pressure on them, they could swell up, even under normal/light duty condition.
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Certified 18650 Cell Reclamation Technician

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#8
Quote:And with this here, 1p20s, is another reason why it sounds like you mean 10 strings of 20 cells. You said "1p". Can be very confusing if you swap terms and mean 10 packs connected in series.
Ah, Rodger, thanks, so I guess that in this case it’s just a 20s pack.

Would splitting the cells up into groups of 5 with an aluminium divider be something to think about, just in case a cell let’s go , or would it just melt through regardless?
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#9
I just don’t like working with pouch cells… so I would pick 18650 for that reason.

Other than that, it’s pretty much the same, just a different form factor. If you build with them, make sure you package them appropriately for protection and expansion.

I guess sooner or later I better get used to it, more and more consumer electronics are using pouch.
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#10
Seems the more I look around, the more I keep seeing pouches that have gone bad. Not sure if it’s just my paying attention to this, but it’s a bit unnerving.
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