I was thinking of modelling some space between the 8th and 9th cell to to accommodate the bent tabs and also serve as nerving to avoid bowing of the sides.
The whole reason is space constraint. I was trying to add as much as i could to the smallest package possible. From what I’ve determined with your packs, the higher the number of cells, the less space is lost.
Well I can’t say for sure what the exact percentage higher these cells are, but I read multiple times it was up to that amount. I’ve been looking at the Samsung 30T, 40T, Sanyo NCR20700C, and a few others, but those are the main ones I’d say…
An inbuilt cell capacity monitoring system would be great
@Ronny_CTS, yes, you are correct. Space is lost at bolt end where it is allocated for holes and cavities.
If you want you terminals to be on one side you cant go 8P+8P, you need 8P+7P. For terminals to be on one side you need uneven count of cells. If you OK with terminals on opposite ends, that means you add same allowance for screw holes and cavities. Then you add your spacing and some wire routing and you are at the point where space saving is negligible if any. Printing might be hard as well. Mine were designed strait away to be printed without supports if you look at the angles .
Try, and you might come up with something 
@uigiroux Take the last one, NCR20700C (3500mah), volumetric density is 21991.15mm^3 if translated to 18650 volume it would hold 2630mah
Sony US18650VTC6 is 3120mah, 19% more dense than you 20700 at the same power (30A).
Take 4 20700, cell are is 1242mm^2 bounding rectangle area of these is 1600mm^2
Take 5 18650, cell area is 1258mm^2 bounding rectangle area - 1620mm^2
4 parallel 20700(NCR C) will give you 14AH and 120A peak
5 parallel 18650(VTC6) will give you 15.6ah and 150A peak.
true, I’m not au fait with powerwalls but I saw a picture of one which had a led beside each cell.
I think leds are the way to go with so many cells, you can glance at the wall and see where a problem exists.
I like this product branch for nese, I’ll try it when I have my own wall and not a rented one where I live now, we get power cuts fairly frequently
Well I’m figuring more than just the voltage but the amps as well, there double on many of those cells.
@uigiroux what do you mean? Volts are the same no matter size. I pointed that soni us18650vtc6 is 19% mkre dense then NCR20700 at the same power or 19% more powerfull at the same volumetric density.
Lol my bad, I meant mAh, not volts 
What about with the Samsung 30T and 40T?
@uigiroux, 30T is worse than ncr, 40T is larger so i would assume same math applies. @banjaxxed How about investing in BT bms so you get audible notification when cells go out of normal? No need to glance anywhere? I just dont like the idea LED’s draining cells 24/7
How are they worse though? Like your completely ignoring amps, there double to even more than double. The mAh isn’t the only important value with these cells.
I am not ignoring amps. Here, 2 examples. INR21700-30T Size - 21700 Capacity - 3000mAh Power - 35A
US18650VTC6 Size - 18650 Capacity - 3120mah Power - 30A
Even this will be better: US18650VTC5A Capacity - 2600mah Power - 35A
I don’t know how can one not see the numbers? I wrote power levels of the two in P groups: 4 parallel 20700(NCR C) will give you 14AH and 120A peak 5 parallel 18650(VTC6) will give you 15.6ah and 150A peak. in the same size package (VTC6 being 20mm^2 larger area (not volume))
I can sum up: 20700, 21700 is crap
Ok but those aren’t the actual values? The VTC6’s are 3000mAh and 15A. VTC5A is 2500mAh and 25A, Samsung 30Q is 3000mAh and 15A. So the 40T has 4000mAh and 30A so for most cells its double amp and 33% more mAh. Samsung 30T is 3000mAh and 35A so more than double A then many buy still about the same mAh. Sanyo NCR20700C is 3500mAh and 30A. Still better than the 18650’s as well…? I’m not trying to argue or anything, I’m new to this stuff until about a year ago, but as far as I see these are much higher amps than most of the smaller cells and usually about 25-35% more mAh.
Those are actual manufacturers numbers and I were comparing them on both sides 18650 vs. 20700/21700 Real world values will vary but they will vary on both sides. I have fully discharged six vtc5a at over 200A.
Well yeah I mean they can discharge at higher levels, but so can the larger sized ones as well. The average levels they are putting out though I imagine has to be relative, so even if they can have burst levels that are much higher, I would imagine that the larger cells have burst levels that are even higher since under normal conditions they are rated higher… Lol I dunno bro, you may very well be right, I just think I’m going to go for the larger ones regardless 
I think you should go for something you like. I like 18650. Its old standard, manufacturing is well worked out.
Thats why my solution is based on 18650 which use 95% of people 
Right on, that probably is the best business decision. I thought the larger sized cells would be becoming much more popular by now but it seems the price is off putting for most…
They make sence in tesla, robots can save a lot of time having less welds to do = money, not so much on small builds like bikes or boards
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