New weldless battery system crowdfunfing project

Batteries, Chargers, and Battery Management Systems.
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Re: New weldless battery system crowdfunfing project

Post by Addy » Mar 21 2019 9:55am

On the other hand, if you clamp too hard you can dent the cell. I have dented some cells when pressing too hard with a spot welder, specifically on the positive side of the cell.

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Re: New weldless battery system crowdfunfing project

Post by john61ct » Mar 21 2019 10:25am

The clamping force needs to not be via a low-area "point", but spread over a flat contact area in order to lower the pressure psi.

Better electrically too, more surface area for lower resistance higher conductivity.

There are conductive epoxies as well, the physical cell-holding force does not need to be exerted by the electrical connection.

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Re: New weldless battery system crowdfunfing project

Post by Grantmac » Mar 21 2019 11:13am

Any plans to scale up to larger formats such as 26xxx cells? Fewer connections is very appealing.

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Re: New weldless battery system crowdfunfing project

Post by john61ct » Mar 21 2019 12:56pm

Same length, just wider.

Should be able to come up with one design works for both, long as per "slice"

Allowing N #of slices to be stacked next to each other would be great, some only want 4-5" thick, others can go lots wider.

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Re: New weldless battery system crowdfunfing project

Post by john61ct » Mar 21 2019 12:57pm

zzoing wrote: thanks to the genius discussions on this forum in about 2014
Anyone know what threads being referenced here?


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liveforphysics   100 GW

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Re: New weldless battery system crowdfunfing project

Post by liveforphysics » Mar 21 2019 3:41pm

john61ct wrote:
Mar 21 2019 10:25am
The clamping force needs to not be via a low-area "point", but spread over a flat contact area in order to lower the pressure psi.

Better electrically too, more surface area for lower resistance higher conductivity.

There are conductive epoxies as well, the physical cell-holding force does not need to be exerted by the electrical connection.
If you have a limited amount of contact pressure, you will find a point pretty fast where more surface area hurts the joint.
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Re: New weldless battery system crowdfunfing project

Post by john61ct » Mar 21 2019 9:03pm


liveforphysics wrote:
john61ct wrote:
Mar 21 2019 10:25am
The clamping force needs to not be via a low-area "point", but spread over a flat contact area in order to lower the pressure psi.

Better electrically too, more surface area for lower resistance higher conductivity.
If you have a limited amount of contact pressure, you will find a point pretty fast where more surface area hurts the joint.
Sorry, don't follow.

What "joint"?

My thinking is that the contact pressure can be higher given the greater surface area spreading the load.


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Re: New weldless battery system crowdfunfing project

Post by spinningmagnets » Mar 22 2019 7:03am

zzoing wrote: thanks to the genius discussions on this forum in about 2014

Anyone know what threads being referenced here?
No Solder / No Weld

"Another No Solder/Weld 18650 Build" (snath, 6 pages [plus more links to other no-solder/no-weld builds])
https://endless-sphere.com/forums/viewt ... 14&t=57810

"18650 battery Kit development and discussion" (agniusm, Another no-solder loose-cell box, 7 pages)
https://endless-sphere.com/forums/viewt ... 5#p1238901

"Conductivity improving grease project" (liveforphysics, 5 pages)
https://endless-sphere.com/forums/viewt ... 14&t=61542

"Modular Rebuildable Repairable 18650 battery." (shawname "Battery Blocks", using magnets to make connection at cell-tips, instead of spot-welding)
https://endless-sphere.com/forums/viewt ... 31&t=76205

"DIY assembly kit for 18650 without spot welding/Soldering" (Vruzend kit)
https://endless-sphere.com/forums/viewt ... 31&t=87434

"yet another solderless DIY battery pack via NIB's" [also using button magnets to hold busses onto cell ends]
https://endless-sphere.com/forums/viewt ... 17#p917007

"Electric Motorcycle (50cc Equivalant)" [19P modules for 14S]
https://endless-sphere.com/forums/viewt ... 10&t=85758

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Re: New weldless battery system crowdfunfing project

Post by spinningmagnets » Mar 22 2019 7:29am

It sounds like...if the positive tip will be dented and caved-in with too much pressure (leading to a contact surface that is no longer flat), the amount of pressure that you can use is limited.

The electrodes on the cell are nickel-plated steel, so they are reasonably stiff and hopefully very flat (no dings from shipment). If the contacts are also made from a very stiff material, microscopic irregularities means that there will be more pressure applied in one area, and less in another. The wider the contact area, the more likely there will be some localized bridging.

Cembre ring connectors are zinc-plated copper, and the copper is annealed to make it as soft and deformable as possible. The first time you tighten it down to a contact, the copper "flows" slightly and conforms to the shape of the contact point (as it is squeezed between the nut and the electrical contact) But after doing that several times, the copper "work-hardens" and becomes brittle.

I mention this because if your contacts are a stiff material they won't deform to mate with the electrode (think of a crumpled piece of paper that you try to flatten out). I know this all sounds like an exaggeration, but if 96% of contacts in a pack are good, that last 4% will have hot contacts from the same amps flowing through less contact area.

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Re: New weldless battery system crowdfunfing project

Post by john61ct » Mar 22 2019 11:42am


spinningmagnets wrote:
zzoing wrote: thanks to the genius discussions on this forum in about 2014

Anyone know what threads being referenced here?
No Solder / No Weld

"Another No Solder/Weld 18650 Build" (snath, 6 pages [plus more links to other no-solder/no-weld builds])]
Wow can't ask for better curation than that, sure beats sorting through hundreds of google results

thank you! owe you some of your favorite bevvy


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Re: New weldless battery system crowdfunfing project

Post by BlueSwordM » Mar 22 2019 12:18pm

zzoing wrote:
Mar 21 2019 5:14am
Silver would get very worn out for an electrical contact. In the industry they have fairly precise micron widths and alloys for the best plating there are probably ASTM grades that you can have if you invest in equipment for it. Nickel micron astm search gives this page https://advancedplatingtech.com/electro ... -services/
That's why I'm going with a triple nickel-copper-nickel plating this time.

In a flashlight, a silver plating welcome, but during soldering and during very high humidity usage, there can be some tarnish forming, and in a battery pack, it would erode away, surely, but slowly.

I'm going to take a picture of a battery holder using my spring+brass contact, so you can see what I've made with it.

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Re: New weldless battery system crowdfunfing project

Post by john61ct » Mar 22 2019 12:20pm

spinningmagnets wrote: If the contacts are also made from a very stiff material, microscopic irregularities means that there will be more pressure applied in one area, and less in another
Very well clarified, thanks again.

OK another tack. Forget physically holding the batts for now, just focus on the electrical contact functionality.

A layer of compressible rubber or relatively dense foam between the batt ends and opposing "clamping rails" maybe say aluminium U-channel.

A small die-cut patch of:
3M ECG7000H series electrically conductive compressible cushioned tape*

holds the fine tinned strands of a fanned-out marine-grade wire

Image
between the battery end and the cushioned surface at each end.

Those two opposing "clamping rails" are tightened toward each other in a controlled manner, like a precise torque wrench.

____
* This one
https://www.3m.com/3M/en_US/company-us/ ... 3294001372

is 28.3 mils / 0.720mm thick, comes in 4" x 10' rolls

excellent gap filling performance

conductivity through the thickness (Z-axis) & in the plane of the adhesive (X-Y planes)




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Re: New weldless battery system crowdfunfing project

Post by john61ct » Mar 22 2019 1:00pm

Sorry for the continued derail, forgot where I was.

Please if you have a reply for me, let's carry on here
https://endless-sphere.com/forums/viewtopic.php?t=99213

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liveforphysics   100 GW

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Re: New weldless battery system crowdfunfing project

Post by liveforphysics » Mar 22 2019 3:31pm

The magic of making this work is to only use materials in the stackup with acceptable compression set behavior. Almost anything squishy you find can work to make a solder less pack for a day. The trick is to make a pack that is still squishing against the cell contacts hard enough for a good electrical joint after years of sitting compressed.

This is why solderless packs aren't a mechanical design problem to solve as much as a materials tech challenge to select things that won't let force creep down to nothing after sitting a while.
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Re: New weldless battery system crowdfunfing project

Post by Chalo » Mar 24 2019 3:00am

liveforphysics wrote:
Mar 22 2019 3:31pm
This is why solderless packs aren't a mechanical design problem to solve as much as a materials tech challenge to select things that won't let force creep down to nothing after sitting a while.
This seems to me to be a point in favor of using a high tensile strength copper alloy as both bus and leaf spring.

But it's an even more compelling reason to solder, weld, crimp, or screw, and not worry about continuity problems.
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Re: New weldless battery system crowdfunfing project

Post by Matador » Mar 24 2019 7:55am

BlueSwordM wrote:
Mar 19 2019 11:39am
What do you mean current capability is too low?

That's why I've made my own BeCu spring design :)

Image

Nickel plated BeCu C17530 springs.

In a dual spring setup, they are absolute monsters, and have no problem handling 20A+ currents.

Image
Been there, done that. https://endless-sphere.com/forums/viewt ... 0#p1213147

Good luck with the springs. Unless you can tell me the resistivity of the nickel coated BeCu metal and if this spring will maintain its recoil and shape when heated to 1000 deg celcius... I think unfortunatly it is likely to fail. In my experience practice shows there are many more challenges is this project than one could imagine with theoretical hypothesis of a concepts. Elon Musk wanted to build Tesla he did. He also so sent the a rocket inspace with a module that docketto ISS and made it back to earth while the rocket relanded safely on eart to be reused. Yet, elon musk has not succeded in building a reliable solderless solution. Can you ? Show us the finished working product in action please...

Matador

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Re: New weldless battery system crowdfunfing project

Post by spinningmagnets » Mar 24 2019 1:48pm

I am not a fan of using a coil-spring as the electrical conductor. Although I admit it's possible that the coil-spring/conductor design might be improved, but...for the near term my biggest concern is the small contact point at the small end of the coil-spring, and where it touches the cell tip. I am uncomfortable with how small the contact point is.

I believe having a separate element for the spring and conductor is a better option, and is still very affordable. Once a pack builder chooses to have the spring and the electrical conductor as two separate elements, I believe a steel leaf spring is best, and a 0.30mm thick copper ribbon is affordable and very well-performing for high amps.

Copper spot-welds poorly (requires expensive equipment to do it right), but is over four times as conductive than the same volume of nickel.

Copper ribbon__=__cross section__=__equivalent round copper wire

7mm X 0.15mm = 1.0mm squared = 17 ga
7mm X 0.20mm = 1.4mm squared = 16 ga
7mm X 0.25mm = 1.7mm squared = 15 ga
7mm X 0.30mm = 2.1mm squared = 14 ga

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Re: New weldless battery system crowdfunfing project

Post by BlueSwordM » Mar 24 2019 2:04pm

Conductivity of BeCu C17530 is at 38% IACS.

The resistance value of both the springs are 9mOhms.
Technically, it's a bit less than that, but 9mOhms is a nice round number, and gives a bit of headroom.

I've also planned of making the 3rd gen spring with a nickel-copper(50um)-nickel plating for additional conductivity and being less expensive and more durable than the 2nd gen spring with a silver plating.

Well, I mean, I only have this battery holder on hand that I've made. Works well to 10A. Can go higher, but the 18AWG wiring gets a bit too hot for my taste above this. Made this using a scrap battery holder, 0,2mm copper strip, a tin plated brass button, 18AWG wires and a scrap XT60 connector I soldered on a whhhiiillle back when I was still a beginner at soldering.

It can very well hold on to a cell for its dear life. Quite hard to get out.

Image

I'm currently working with a manufacturer to provide a 2P3S/2P4S/2P5S battery holder

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Re: New weldless battery system crowdfunfing project

Post by BlueSwordM » Mar 24 2019 4:47pm

Also, this is quite the lengthy spring.

By making it shorter, I can easily lower the resistance of the spring.

@Matador, did you mean 100C or 1000C? Because nothing is going to resist that much heat at 1000C :)

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Re: New weldless battery system crowdfunfing project

Post by zzoing » Mar 25 2019 11:02pm

What do you think about polycarbonate? it's one of the highest Tg plastics, but some forms of PC have scratch proof coatings which crack from water and oil, and there are different makes of PC. I wonder if all polycarbonate is to be ruled out for structural pieces of a motorbike/battery box? There are other options than PC of course, HDPE and ABS are the only 2 other comparatively high temperature plastics that I know well.

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Re: New weldless battery system crowdfunfing project

Post by Rube » Mar 26 2019 4:22am

Polycarbonate is hygroscopic, I am not sure if this affects the suitability but worth considering.

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Re: New weldless battery system crowdfunfing project

Post by zzoing » Mar 28 2019 11:30pm

Some varieties of lexan have an stiff coating which reacts with water and oil. ABS and HDPE, i.e. lego and bottle plastic are the other plastics with see through grades that i know. ABS is cool because 3d printers can add pieces using abs slurry.

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Re: New weldless battery system crowdfunfing project

Post by john61ct » May 30 2019 11:12pm

amberwolf wrote:
Mar 06 2019 11:54pm
EIG's bolt-together system on their OEM batteries seems to work fine. I've been using them for years on CrazyBike2 and SB Cruiser, with DIY interconnect bars since I didn't have the OEM ones.
I don't see a thread talking about this, just their cells.

Have you got a link to the weldless construction of their packs?

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Re: New weldless battery system crowdfunfing project

Post by e-beach » May 30 2019 11:26pm

BlueSwordM wrote:
Mar 24 2019 4:47pm
Also, this is quite the lengthy spring.
By making it shorter, I can easily lower the resistance of the spring.
@Matador, did you mean 100C or 1000C? Because nothing is going to resist that much heat at 1000C :)
I have tried spring mounted battery experiments a few times. The springs could not take the amps and always melted. If you are going with springs they need to be really-really beefy!!! to take the amp draw.

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Re: New weldless battery system crowdfunfing project

Post by amberwolf » May 31 2019 12:39am

john61ct wrote:
May 30 2019 11:12pm
amberwolf wrote:
Mar 06 2019 11:54pm
EIG's bolt-together system on their OEM batteries seems to work fine. I've been using them for years on CrazyBike2 and SB Cruiser, with DIY interconnect bars since I didn't have the OEM ones.
I don't see a thread talking about this, just their cells.

Have you got a link to the weldless construction of their packs?
https://endless-sphere.com/forums/viewt ... G#p1322357

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