Watts-on's "SpringSlot" 18650 Battery Holder

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watts-on

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Joined
May 27, 2017
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188
I have had this idea bouncing around my head for a while now, but since I've decided to build one ( or some :) ) of Brett's Charge/Discharge Testers, I just didn't fancyusing any ofthose single 18650 holders.
So I thought it was time to turn my idea into reality:


image_ypxxql.jpg


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

Some exploded Views:


image_qolxtw.jpg

image_vmrert.jpg


I have attached the STL files if anyone wants to 3D printtheir 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 :D


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.
 

Attachments

  • SpringSlot_Ver1b_STL.zip
    575.2 KB · Views: 514
  • SpringSlotPartsList.txt
    2 KB · Views: 384

wim

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Apr 6, 2017
Messages
556
Clever ...
Gotta get me a 3-printer thingy real quick :)

Oh, and liked the video ... great job, we need more of them.
 

Crimp Daddy

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Feb 21, 2018
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962
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...
 

rev0

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Oct 3, 2017
Messages
369
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.
 

Korishan

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Jan 7, 2017
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6,549
Awesome! :cool:
 

watts-on

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May 27, 2017
Messages
188
rev0 said:
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 currenttesting 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 thoughI'm pretty sure it will be good for 1000mA standard testing current.

rev0 said:
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 lookin the video. I'm not used to doing and filming at the same time. :)

wim said:
Gotta get me a 3-printer thingy real quick :)

CrimpDaddy said:
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 disappearwithout a trace. :D
 

Korishan

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Jan 7, 2017
Messages
6,549
watts-on said:
wim said:
Gotta get me a 3-printer thingy real quick :)

CrimpDaddy said:
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 disappearwithout a trace. :D

LOL As Phizicks and Travis have experienced hours of endless dabbling with their beasts
 

Bubba

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May 9, 2018
Messages
300
Thanks for the stl Watts-on.

I like the 4 holder and it will fit nicely on my printer.
 

hbpowerwall

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Oct 7, 2016
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1,984
this is great & awesome work on the video!!!
 

GaryMatthews

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Sep 6, 2018
Messages
1
watts-on said:
rev0 said:
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 currenttesting 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 thoughI'm pretty sure it will be good for 1000mA standard testing current.

rev0 said:
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 lookin the video. I'm not used to doing and filming at the same time. :)

wim said:
Gotta get me a 3-printer thingy real quick :)

CrimpDaddy said:
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 disappearwithout a trace. :D

Lol. start a project and afew minutes later police are kicking the door in...."been on missing person for last three months what have you been up to?"..."nothing sir.. just playing with my 3d printer.". I just printed it without supports and had a fairly successful result. cheers and keep up the good work. :)
 

watts-on

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May 27, 2017
Messages
188
Thanks guys. :cool:

watts-on said:
rev0 said:
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 currenttesting 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 thoughI'm pretty sure it will be good for 1000mA standard testing current.

Brass nuts have arrived so have done a quick load test. After 5 mins at 10A the terminals were barely above ambient:


image_mydtpb.jpg

image_pqhlfc.jpg


28.8C in ambient of ~21. That was way better than expected. :)

hbpowerwall said:
this is great & awesome work on the video!!!

Thanks Sir Pete! I feel honoured :D

GaryMatthews said:
Lol. start a project and afew minutes later police are kicking the door in...."been on missing person for last three months what have you been up to?"..."nothing sir.. just playing with my 3d printer.".

Haha, If Einstein had had a 3D printer he would have written a whole theory about it. :)

GaryMatthews said:
I just printed it without supports and had a fairly successful result. cheers and keep up the good work. :)

Yeah, I designed it to print without supports, hoping that would work for everyone.
Did you have any suitable spring? I designed it to take left or right wound versions in case that was required.
 

BlueSwordM

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Jul 5, 2017
Messages
423
@Wattson, what is the Vdrop on these brass nuts?

I would be interesting so I could calculate the power loss and the resistance of the contact itself.
 

watts-on

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Joined
May 27, 2017
Messages
188
rev0 said:
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 said:
@Wattson, what is the Vdrop on these brass nuts?

I would be interesting so I could calculate the power loss and the resistance of the contact itself.

I did some more measurements:

Using a copper conductor in place of the cell, and with the PSU outputting 10A @ 0.621V the voltage across the solder tags at each end of the holder was 25mV.

Let me know if you need any other measurements taking.
 

watts-on

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May 27, 2017
Messages
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brettwatty said:
Mate that is genius and awesome. I need some for my Charger / Discharger. Now to buy a 3D printer. Hmmm will my wife let me hmmm.........

Thanks mate. I'd send you a set, but postage from the UKis going to be eye watering.

Pete's a lot closer, and he's got a shiny new printer andneeds something topractice on... :D
 

unclebob

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Jul 11, 2018
Messages
58
watts-on said:
brettwatty said:
Mate that is genius and awesome. I need some for my Charger / Discharger. Now to buy a 3D printer. Hmmm will my wife let me hmmm.........

Thanks mate. I'd send you a set, but postage from the UKis going to be eye watering.

Pete's a lot closer, and he's got a shiny new printer andneeds something topractice on... :D

watts-on, how much you selling these for - im in london
 

watts-on

Member
Joined
May 27, 2017
Messages
188
unclebob said:
watts-on, how much you selling these for - im in london

I haven't really though about selling them. How many are you looking for and would you want just the printed parts or with the spring and contacts?
I've no idea how much. Maybe I should ask, how much would you expect them to be?


watts-on said:
brettwatty said:
Mate that is genius and awesome. I need some for my Charger / Discharger. Now to buy a 3D printer. Hmmm will my wife let me hmmm.........
Thanks mate. I'd send you a set, but postage from the UKis going to be eye watering.

Actually I just checked and postage is a lot less that I was expecting. If you PM me a delivery address I'll send you a set. It's the least I can do after all the hard work you've put into the Charger /Discharger project.
 

Travis Watson

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Aug 6, 2017
Messages
60
What size brass screws are you using? I think I might give this design a shot. I need to build another 24 slot board.
 

watts-on

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Joined
May 27, 2017
Messages
188
TravisWatson said:
What size brass screws are you using? I think I might give this design a shot. I need to build another 24 slot board.

They're M3 Cheese head. Thread length 10, head thickness 2mm. They're too long butI already had themin stock.6mm thread would be plenty.
 
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