Building a 18650 cell case without soldering

Batteries, Chargers, and Battery Management Systems.
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currentFlo   10 mW

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Building a 18650 cell case without soldering

Post by currentFlo » Jun 26 2013 4:29am

Hi all,
I see 18650 cells are gaining more popularity these days, but making a pack with these cells is not so easy and requires in much cases a spot welder...
Do you think it would be possible to build a case for holding and connecting 18650 cells and also to allow easy replacement maintenance operations on them ?

I have two starting point in mind:

Idea 1: building something based on this kind of connectors:
millmax.png
millmax connector
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012.4M.pdf
millmax datasheet
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Idea 2: Create a new type of holder block with build-in connection plate which would allow to create easily any type of serie/parallel configuration/ pack size:
p1110222.jpg
holder
p1110222.jpg (133.19 KiB) Viewed 467 times
Last edited by currentFlo on Jun 27 2013 7:13am, edited 4 times in total.
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Re: Building a 18650 cell case without soldering

Post by silviasol » Jun 27 2013 3:58am

It would be way to complex unless you have a really good idea for a setup. Any bump and the cells could move or all displace.
I just made half of my soldered pack in the thread I posted a few days ago. It has been tough and I will not do it again however so far it looks good. I did find a welder on ebay I am going to buy for my next build.
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Re: Building a 18650 cell case without soldering

Post by TheBeastie » Jun 27 2013 4:12am

I like it, most things that need replacement over time have connector setups that don't require solder, even car batteries. Something like this has to come into existence sooner or later.
Main reason I have never built a 18650 battery is because of stuffing around with soldering.
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migueralliart   10 kW

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Re: Building a 18650 cell case without soldering

Post by migueralliart » Jun 27 2013 9:41am

The only problem I see is the contact between a spring loaded tab and the cell is not always the best. I agree it would be pretty cool to have something like those blocks that you can drop in cells and remove them when they are in bad shape.

I know a member here in the past was working on something similar for A123 cells (26650) but it never finalized.

The ideal thing will be to have a main holder at the center of the cells and then two caps for top and bottom and studs at the end that you could tie to a certain pressure so that you get correct contact. Maybe we'll see such a thing soon :D

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Re: Building a 18650 cell case without soldering

Post by Doctorbass » Jun 27 2013 10:36am

2009-2010-2011 ZERO MOTORCYCLES BATTERY ASSEMBLY METHOD:

One great and ingenious method that already was in use by zero motorcycle is to use copper braided strap with rubber ring to hold them on the top of neg and po of the cells! Then you can add a heatshrink to add pressure and avoid rubber to move.

Easy, cheap and easy to repair your pack.

for the rubber they used some bicycle tire rubber tube sliced to form some ring ! the advantage is that these rubber do not dry very fast and they are not too affected by moisture or temperature so they sustain pressure between the copper braided strap and cell tab very well!

Here is couples of pictures i took when i had to do some maintnance on a ZERO battery for a friend of mine. This battery was made to take 300A burst and i s a12P config meaning about 25A per cell tab and only holded by a rubber tensil pressure!
Please note that these are 26700 cells and each cylinder is in fact 2s1p ( 7.4V):

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Re: Building a 18650 cell case without soldering

Post by sabongi » Jun 27 2013 12:10pm

Really nice doc.... is that a sleeve between the cells?

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Re: Building a 18650 cell case without soldering

Post by circuit » Jun 28 2013 1:35am

You should not do it like that... You have covered pressure release valve. Some ugly things can happen to it.
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Re: Building a 18650 cell case without soldering

Post by mistercrash » Jun 28 2013 10:16am

From what I see in the pic, the valves are not near completely covered, there's plenty of space for the valves to release their gases. I'm a noob and I don't know anything and I would do it like that in a heartbeat. Thanks for sharing Doc. With 18650 cells, I would make sure that the O rings to protect from shorts on the positive leads are installed. I just wish I knew where to get them.
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Re: Building a 18650 cell case without soldering

Post by currentFlo » Jun 28 2013 5:03pm

Hi Doc,
thanks for sharing this method which i very ingenious and cheap, however it seems to require heatshrink to ensure nothing is moving in the battery pack, this makes changing one of the cells not so easy... also i'm not sure there is sufficient space around the cells to allow air cooling. I keep thinking a solution based on modular plastic holders with integrated connectors has an interest !

I will try to take time to design a basic 18650 holder block in 3D to show what I have in mind :) Do you know something better than Google sketchup to do that kind of work ?
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Re: Building a 18650 cell case without soldering

Post by flathill » Jun 28 2013 5:25pm

ALREADY DONE :D

fiberglass PCB with temp/volt monitoring of every cell
thermally conductive PCB to Al shell
NO MORE Spaghetti

currentFlo   10 mW

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Re: Building a 18650 cell case without soldering

Post by currentFlo » Jun 28 2013 6:08pm

good ! but not modular and seems expensive ! :D
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Re: Building a 18650 cell case without soldering

Post by imorton » Jun 28 2013 6:40pm

currentFlo wrote:good ! but not modular and seems expensive ! :D
And only available to OEM's…. :(
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Re: Building a 18650 cell case without soldering

Post by TheBeastie » Jun 28 2013 8:28pm

Yeah I demand standards to be 3D friendly now!... Is this the world we live in now?
I can half imagine it my self now, a 3d printed holder thing with fat connector springy things.
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Re: Building a 18650 cell case without soldering

Post by cwah » Sep 12 2013 9:49pm

I love your work doc, I'll do the same :lol:
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Re: Building a 18650 cell case without soldering

Post by Honk » Sep 13 2013 5:49am

Here 's how you build a solder and weld free battery box. Works with any regular cell type.
Well, almost free, the wiring and output connector must be soldered.
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