I’m looking at building another board and have been eyeing the ubox v2 ESC. Now Im temped as hell to go for a 20S 6P build but I am limited to an 18650 cell size because of the fluxmotion deck/enclosure. I still want a solid amount of range so I am a bit worried that if I go 6p, I will have to get lower capacity cells in order to have the current output that I need. 10P makes it easier for me to find cells, but what is the advantage of 18/20S over 12S, I can gear the board to go just as fast in either case by switching to higher KV motors, and want to know if there are differences im not seeing.
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At 20S you will be using less battery amps. Power draw = voltage x current, so if you have higher voltage, you need less current. The cell count is the same, so each cell will still see the same power draw, so your cell choice is independent from what pack configuration you go with.
TL;DR:
If you can get both the top speed and startup torque you want with just gearing and kv choices alone on 12s (and your ESC isn’t overheating), then there’s no real reason to go with high voltage.
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Sorry to be the guy objecting to the premise of the question, but you can absolutely fit 21700 cells in a flux enclosure. I’ve seen up to a 12s9p 21700 in there. There’s lots of documented builds with that configuration if you search around on ther forum 
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Oh lol, that makes my life easier then, I was just going off of the spec sheet
12s8p, there was definitely room for 12s9p, just would have been more annoying to make
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Maybe his got the v2 injection molded enclosure. at which case it should still fit just a bit more creative maybe
The early v1s you need a gasket to fit 21700. I actually have both of them for my flux
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Injection molded ABS works great as a buck for fiberglass.
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Discharge curve plays a role towards what loads you can draw, but in general you can rely on Wh rather then Ah when it comes to capacity, aslong as you stay withing reasonable limitations of the cells.
Example:
20S6P => U * Ah = 20 * 3.7 * 3Ah * 6 = 1332Wh
12S10P => 12 * 3.7V * 3Ah * 10 = 1332Wh
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Why no one’s talking about working voltages in relation to boards’ speed as the battery drain?
20s has 28V difference between full charge and drained while 12s only has 16.8V. What happens is that a 20s the board will be very fast while the battery is in high SOC and is very slow when drained down. A 12s board will have lesser performance gap.
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I was thinking this, but I ultimately think this isn’t applicable. Both batteries would lose the same % voltage. If you gear both boards to 20mph, they should both be going like 14mph near dead since its the same % change in voltage.
if you run the same gear ratio/motor kv on both setups, the 20s build will lose more speed, but the % decrease in top speed should be the same as the 12s setup.
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Great news, you’re not! You can fit 20S6P 21700 in there if you get crafty…
(Not my picture) @Heathlewis ^
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Thanks a lot for the enlightenment!
My misconception came from personal experience with scooters which have fixed gear ratio.
Didn’t actually believe it until I did this math on variable drive train ratio.
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20s 140kv 5.2:1 ratio is a rocket
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20S 170KV 5.2 too 
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Whats your top speed?
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My relatively uninformed opinion is that 12s is tried and true with abundant options for motors, chargers, and ESCs.
Everything with 20s is more expensive and I don’t really understand how it would be better.
@jack.luis would love to hear your thoughts on high voltage (Rocinante) vs 12s?
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Everything 16s is not more expensive with the new makerx escs. Only thing that’s more expensive is the BMS.
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And waaaayyyy fuckin bigger
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