Hmm I’m inclined to bump up my settings now 
True, there is a lot of space wasted. But going by the rated capacity and dimensions of a 2.2ah 4s turnigy graphene, it has a volumetric energy density of just a hair over 200wh/l. A single flat layer of 18650-30Q cells (Including the air space!) has a volumetric energy density of 514 wh/l. Bare cells are 633 wh/l.
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I thought cylindrical lion cells are less space efficient than squared lipo cells. i.e., you can fit more chemistry into the corners of the square which would have been lost due to the circular shape of lion cells. Looking at your 18650 pack there’s always gap between cells, now imagine you make a battery pack with square corners it would utilize all the gap and give you some extra capacity/discharge.
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See above. It’s true that there is less room for battery chemicals. But, the battery chemistry is SO much better, that it still way outperforms RC pouch cells in terms of energy/l or energy/kg.
lipos still win in terms of watts/l and watts/kg though.
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If you dont switch, @least try lipos.
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Then why don’t we have squared lion cells instead of the stupid cylindrical cells then!!!
Lipo have a nice discharge curve too staying high before finally out of juice. That’s worth something. And probably can charge them much faster without damaging.
Because the construction of the layers inside is a jelly-roll. Try and make a square cinnamon roll, and you’ll see why.
Another reason is that the layers tend to try and puff up, expanding away from each other during high discharge, etc. The cylindrical shell applies even pressure from all sides and has no tendency to buckle in one direction or another. This is why large packs of prismatic li-ion cells always have some sort of structure to keep the cells compressed. Cylindrical cells have that built in already.
If you made square cans, the flat sides would bulge out due to the forces applied to them simply from the assembly process, much less from the layers trying to puff over time.
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You can compress lipo. Think it’s good for them.
I think lipo are safer given the track record here. So many cells and possible points of failure with ion vs plugs and fewer cells. Just scratching off the insulation on ion can be disaster
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Yep. But we don’t usually because it’s a pain and takes extra space/weight/engineering to do it.
Buy round li-ion, and they’re pre-compressed.
I think those are like the turds that Evolve use, but I’m not 100% sure. I bet @longhairedboy knows. These seem to be the exact ones they use in Carbon GT. Stay as far away from these things as you possibly can. But if you wanted a pile of used ones to play with, I bet some are available
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Maybe. What if the round shape allows a machine to roll that sucker up super-tight with thin layers, making it more efficient? I agree with you, but there are known-unknowns and probably unknown-unknowns here
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Exactly. All I’m saying is, there’s gotta be a reason so many EVs (And other industries) use cylindrical cells. If they were a shitty idea, everyone would be using pouch lipos for everything.
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Pouch lipos are in cell phones, tablets and etc. As far as large scale industrial manufacturing goes, companies like the one that makes iPhone batteries have the machines capable of consistent production. This guy, whom I believe is with revoelectric, has some interesting things to say about it: https://www.rcgroups.com/forums/showpost.php?p=29238904&postcount=1774
This is linked in the main article I linked a few posts up. Tldr, it seems that industry is tooled for liion and small capacity lipo manufacturing, but not really for large capacity lipo manufacturing. And as the graphene lipos are fairly new among lipos, commercial adoption may be limited to hobby batteries for a while.
My thoughts anyway, but what do I know. Pretty much thinking “out loud”
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But lipos have their cables which take up space as well Its not like you would put something where the empty space of li ions is
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The shape of that box, I don’t think you can get interesting lipos in there.
Plus, the diyelectric esc most likely has voltage cutoffs for lithium ion, not lipo.
Plus, if you do the same thing to the lipos that you did to the 10s2p pack, 
The cheapest decent lipos are usually the 30c or 40c hobbyking, zippy or turnigy. Usually 3s or 4s for the shape (makes 10s difficult).
You can hit 10s with 2s or 5s lipos (usually), both of which will be difficult to fit I think.
yeah… it costs to be careless, especually if youre going to dump the voltage every ride
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How did you over discharge? I think that esc has lvc, and I think I see a bms?
Yo, I have the exact same enclosure with 2 4S 4500Mah Zippy Lipo, looking for an upgrade actually because 4.5Ah with 8S is pretty poor, I have an actual 12Km range and a 30km/h top speed. Mounting a bms need some knowledges, I could do it again if I change for 10S or 12S but i’ll Need some time so it’ll be better to have one bms included battery !
However this is how it look like with my 2 4S +Bms
Mounting a Sanyo 10S 8.1Ah looks like to be an interesting idea, 27Km range estimated with a higher top speed (10S…) but the max amp is way lower than with my 45C pack from where I can suck 50A easily, there i’ll Need to go for only 30A and I don’t really know what will happen.
However it could be a noice choice because Bms is integrated and they are made to fit our ownboard/meepo enclosure !
Keep me updated tho !
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