18650 16S11P vs. 21700 16S8P battery pack

[raggertje]

I’m planning a 60V battery pack build. The space in my frame can contain a maximum of:

• 176 18650 cells 16S11P or

• 128 21700 cells 16S8P.

The cells I was thinking of are Samsung INR18650-30Q or Samsung INR21700-40T.

Planning to draw a maximum of 120A and maybe max. 200A when the Nucular 12F arrives.

Price, range and weight is almost identical of the 2 packs. 16S11P 18650 has more Parallel which should be better concerning heat but the 40T has more capacity. Which configuration/cell would be a good choice?

 

[goatman]

30q has the self discharge problem, i think of a 40T as a 30Q in a bigger can
RG12 builds 40T packs and i think he had a 40T self discharging

if youre going to run in cooler temperatures you might want to consider the molicel P42a/21700
you can check out the second page of my p42a test to see how it performs against a 40T at -10 celsius and how its performing better with 15amps
theyre about the same cost as a 40T

p42a
https://endless-sphere.com/forums/viewtopic.php?f=14&t=107573&start=25#p1596515

 

[raggertje]

if youre going to run in cooler temperatures you might want to consider the molicel P42a/21700

Thanks for pointing that out goatman, due to limited space I'm going to hotglue the pack. The pack will be placed in an enxlosed alumium box in my frame. Do you think the molicel P42a/21700 are up to that? Warm days are rare here in the Netherlands :wink:

NKON are expecting BIG shipment of cheaper stock then €5.75 is to arrive around march 18 and maybe it's worth the wait...

 

[goatman]

p42a is kind of volt saggy at 15 amps/8p-120amp

hot glueing the pack together will drive the pack temperatures higher than when using cell holders

40T and 30Q can be charged immediately after using without losing any life cycle

i think charging a p42a right away will cut its life cycle by half, ill check that today

if your battery is going to live outside in cooler temperatures, like when youre at work all day, id probably go with p42a

if the battery lives inside id go 40T

ES member PWD built a 40T pack that does 15amps/cell, look at my 40T test, he just said theres a new 40T-3
https://endless-sphere.com/forums/viewtopic.php?f=14&t=106550&start=25#p1618296

 

[raggertje]

Thanks goatman, do you think a hotglued 40T 16S8P pack wil run cooler then a 30Q 16S11P pack?

 

[goatman]

if you glue a 30Q pack together and 1 cell starts self discharging it will be a nightmare to try to repair it unless desulfating works on the 30Q

its like you said above, the 30Q and 40T are the pretty much the same price

so why not do the 40T?

11p of 30Q at 120amps is 11amps max, you shouldnt overheat
11p of 30Q at 200amps 18amps max, youll probably over heat

8p of 40T at 120amps is 15amps you shouldnt overheat but ask PWD https://endless-sphere.com/forums/viewtopic.php?f=6&t=98286&p=1558753&hilit=pwd+40t#p1558753
8p of 40T at 200amps is 25amps youll overheat

i wouldnt glue batteries together, i think Vortecks just used a double sided tape in one of his recent battery builds
https://youtu.be/7YI_1e3uygA?t=694