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Watts-on's "SpringSlot" 18650 Battery Holder
#1
Lightbulb 
I have had this idea bouncing around my head for a while now, but since I've decided to build one ( or some  Smile  ) of Brett's Charge/Discharge Testers, I just didn't fancy using any of those single 18650 holders.
So I thought it was time to turn my idea into reality:



It has a spring loaded lever that allows you to effortlessly insert or remove a cell just by pressing it.

Some exploded Views:



I have attached the STL files if anyone wants to 3D print their own.

edit:
Re-uploaded the attached zip file as a forgot to add all the files to it.

Also, I did a YouTube video too.  Hope you like it.  Go easy on me though, it's my first one ever  Big Grin



Edit: Hardware list for non-printed parts (vitamins):
Code:
Main Assembly
1 x Peg Spring.  See note 1
2 x M3 x 6mm Brass Screw ( pan or cheese head).
2 x M3 Brass Washer.
2 x Brass Nut.
2 x M3 Tag (Solder Or Crimp)
1 x M3 x 25mm Screw (any material) see note 2.
1 x M3 Nut (any material). see note 2
2 x Wires. See note 3.

Auxiliary parts:
2 * 3mm fixings. See note 4.


Note 1.
The most critical component is the spring and can be found in mass produced clothes pegs. I purchased mine in my local super-market in the UK, so I assume these are easily available in other countries.
The coil must be no longer than 11mm, no larger that 7mm diameter, have a core hole large enough to accept the 3mm shaft/thread used for the pivot.
The ones I used had a hole that was slightly too small, however, as you see in the video, you have to re-form them to get the correct angle for the spring to work. This has the added benefit that it opens up the core hole just enough to make it the perfect clearance.

Note 2.
The M3 x 25mm screw and nut are for the lever pivot. If side stacking multiple slots at 1 inch pitch it is advisable to use a countersunk M3 x 25mm since these are slightly shorter than 25mm pan head screws.
This will ensure the screws do not clash with the ones in adjacent slots.
In the case of the 4 gang slot, a 102mm length of M3 studding should be used instead of 25mm screw.
Alternatively, any 3mm diameter material can be used as the pivot provided it is durable enough.

Note 3.
The wire requirement will vary depending on application and required current. As an example, for my PCB mounted ones I used 15mm x 1.2mm diameter solid copper for the positive, and 50mm of 16/0.2mm insulated wire for the negative. Add a loop or two to the wire to help eliminate metal fatigue during operation.


Note 4.
Two countersunk holes are provided in the base to allow for fixing the slot to a surface.  As an example. for PCB mounting use M3 x 8mm. alternatively, wood screws or self-tapping screws with a suitable sized countersunk head could be used.
The-J-Man, nikita, Redpacket And 18 others like this post


Attached Files
.txt   SpringSlotPartsList.txt (Size: 1.99 KB / Downloads: 37)
.zip   SpringSlot_Ver1b_STL.zip (Size: 575.18 KB / Downloads: 103)
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#2
Clever ... 
Gotta get me a 3-printer thingy real quick  Smile

Oh, and liked the video ... great job, we need more of them.
___________________________________
18x 300Wp solar off grid and 10x 180Wp solar tracker grid-tie
10KW 3phase hybrid inverter. 40Kwh 18650 storage (for now)
My setup: https://secondlifestorage.com/t-Instant-powerwall
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#3
Very cool, i'm always impressed by these home brew DIY creations.

I could buy a 3D printer right now, what I can't buy is some 3D CAD skills...
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#4
Have you done any resistance measurements of this holder? Like what the voltage drop is from the PCB to the cell +/- under 1A load? Would be interested on how it compares to the normal spring holders. Though it looks like this will be reserved for special applications, seems it takes a long time/lot of effort to assemble each one.
BlueSwordM and Crimp Daddy like this post
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#5
Awesome! Cool
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Certified 18650 Cell Reclamation Technician

Please come join in general chit-chat and randomness at Discord Chat (channels: general, 3d-printing, linux&coding, 18650, humor, ...)
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#6
(08-31-2018, 08:27 PM)rev0 Wrote: Have you done any resistance measurements of this holder? Like what the voltage drop is from the PCB to the cell +/- under 1A load? Would be interested on how it compares to the normal spring holders.

I haven't done any current testing yet, as I am waiting on delivery of some brass nuts.  The ones I'm using at the moment are stainless steel which is about the worst possible material since this design relies on the current traveling through the thread and then the nut to reach the ring tag.  The brass nuts should be much lower resistance.  Either way though I'm pretty sure it will be good for 1000mA standard testing current.

(08-31-2018, 08:27 PM)rev0 Wrote: Though it looks like this will be reserved for special applications, seems it takes a long time/lot of effort to assemble each one.

Yeah, it's only really for charge/discharge tester applications.  It's easier to assemble than I made it look in the video.  I'm not used to doing and filming at the same time.  Smile

(08-31-2018, 05:17 PM)wim Wrote: Gotta get me a 3-printer thingy real quick  Smile

(08-31-2018, 07:11 PM)Crimp Daddy Wrote: I could buy a 3D printer right now...

Noooo, don't do it!.  All 3D printers have a time dilation field in their immediate vicinity.  Hours of time seem to disappear without a trace.  Big Grin
Geek and Korishan like this post
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#7
(08-31-2018, 10:08 PM)watts-on Wrote:
(08-31-2018, 05:17 PM)wim Wrote: Gotta get me a 3-printer thingy real quick  Smile

(08-31-2018, 07:11 PM)Crimp Daddy Wrote: I could buy a 3D printer right now...

Noooo, don't do it!.  All 3D printers have a time dilation field in their immediate vicinity.  Hours of time seem to disappear without a trace.  Big Grin

LOL As Phizicks and Travis have experienced hours of endless dabbling with their beasts
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Certified 18650 Cell Reclamation Technician

Please come join in general chit-chat and randomness at Discord Chat (channels: general, 3d-printing, linux&coding, 18650, humor, ...)
(this chat is not directly affiliated with SecondLifeStorage; VALID email req'd)
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#8
Thanks for the stl Watts-on.

I like the 4 holder and it will fit nicely on my printer.
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#9
Very impressive!
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#10
this is great & awesome work on the video!!!
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