Spacer/Holder for 21700 cells

Valman · May 24, 2019

I'm considering building a battery pack from samsunc nmc cells in the more modern 21700 size format - using samsung inr21700-40t cells. I can't find anyone supplying hexagonal spacers in the 21700 size - can anyone here advise if they've seen someone selling 21700 spacers in a hexagonal layout instead of square layout?

thanks!

ThierryGTLTS · May 24, 2019

Here for Europe.

https://enerprof.de/shop/accessories-components/battery-cells-carriers/18650-cell-holder-plasticy-for-2-x-21700-battery-cells/

Fits well Samsung 21700 50E.

Have a Nice Day.

Thierry

wiredsim · May 24, 2019

I was looking for the same, and haven’t found any 21700 hex end brackets. However I did find this:

https://m.aliexpress.com/item/32959655606.html?pid=808_0000_0101&spm=a2g0n.search-amp.list.32959655606&aff_trace_key=&aff_platform=msite&m_page_id=7453amp-oF6ibMXXl5v-TseYb1QCLQ1558708660239

Addy · May 24, 2019

If you have access to a 3D printer, you can use these cell holders:
https://www.thingiverse.com/thing:3029966

They're customizable, so you can make them fit 21700 cells easily.

Valman · May 28, 2019

Addy said:
If you have access to a 3D printer, you can use these cell holders:
https://www.thingiverse.com/thing:3029966

They're customizable, so you can make them fit 21700 cells easily.

Thanks so much - that's totally amazing! I'll post pics once it's done - I can't yet make my mind up on whether to go NMC or LPO

Matador · May 28, 2019

What are your power density requirements (in Watts per kg of battery and Watts per liter of battery) ?

What are you energy density requirements (in Wh per kg of battery and Wh per liter of battery)?

In general i would go for NMC. But if you ne crazy power from a relatively small battery, if you need crazy high cycle life from a small battery and if you don't mind lower capacity for given battery size, LFP could be advisable... Especially the A123 nanophospate LFP cells.

Matador

Valman · Jun 5, 2019

Matador said:
What are your power density requirements (in Watts per kg of battery and Watts per liter of battery) ?

What are you energy density requirements (in Wh per kg of battery and Wh per liter of battery)?

In general i would go for NMC. But if you ne crazy power from a relatively small battery, if you need crazy high cycle life from a small battery and if you don't mind lower capacity for given battery size, LFP could be advisable... Especially the A123 nanophospate LFP cells.

Matador

Thanks, I originally thought it pretty much 'had' to be lifepo4 for safety, but it seems like using nmc and other chemistries with careful management isn't uncommon for ebikes, scooters and similar applications - I'll go nmc to get the most out of the battery compartment space that I've got

Valman · Jun 5, 2019

Valman said:
Addy said:

If you have access to a 3D printer, you can use these cell holders:
https://www.thingiverse.com/thing:3029966

They're customizable, so you can make them fit 21700 cells easily.

Click to expand...

Thanks so much - that's totally amazing! I'll post pics once it's done - I can't yet make my mind up on whether to go NMC or LPO

Turns out 3d printing is more expensive than I expected, I was thinking like £50 or something - the 3dhubs quote was over £200

guess I'll need to look into other options

Addy · Jun 5, 2019

Valman said:
Turns out 3d printing is more expensive than I expected, I was thinking like £50 or something - the 3dhubs quote was over £200 guess I'll need to look into other options

That's a shame. At that point it's almost cheaper to buy your own 3D printer and print the holders yourself. Were you looking at exotic plastics or was the price really that high for standard plastics?

Valman · Jun 6, 2019

Addy said:
Valman said:

Turns out 3d printing is more expensive than I expected, I was thinking like £50 or something - the 3dhubs quote was over £200 guess I'll need to look into other options

Click to expand...

That's a shame. At that point it's almost cheaper to buy your own 3D printer and print the holders yourself. Were you looking at exotic plastics or was the price really that high for standard plastics?

Just standard ABS. PLA is a bit cheaper but I read that it's too brittle to use for functional parts and meant for display only. You don't even want to know how expensive for the special fire and chemical resistant plastics etc.. I guess one of the problems is that not many home 3d printers are big enough for a 235 x 154 x 100mm box. Maybe I can find a cheaper 3d print service, I thought 3dhubs was the biggest and most well known one but maybe they add a lot of middleman profit, I'll see if I can find some more direct way

atarijedi · Oct 15, 2019

I was wondering if you ever found any of the 21700 honeycomb style holders, I'm looking at building a battery myself, but might end up having to use the half-cell holders in order to get that staggered design.

mati · Oct 16, 2019

Some library is starting to have 3d printers that is free to use or pay a small fee.
Download a file from thingiverse or make your own 3d model,
upload a stl.file to 3d printer and wait patiently.

fastorquer · Aug 11, 2021

Just updating this thread with a link to Hexagonal 21700 cell holders that are these days available cheaply from China.

https://www.aliexpress.com/item/400...o.store_pc_groupList.8148356.4.4c663ba9GAjZCU

Spacer/Holder for 21700 cells

Valman

100 mW

ThierryGTLTS

1 W

wiredsim

10 W

Addy

100 W

Valman

100 mW

Matador

100 kW

Valman

100 mW

Valman

100 mW

Addy

100 W

Valman

100 mW

atarijedi

100 W

mati

10 mW

fastorquer

1 mW

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