New weldless battery system crowdfunfing project

Batteries, Chargers, and Battery Management Systems.
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zzoing   10 kW

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New weldless battery system crowdfunfing project

Post by zzoing » Mar 05 2019 10:05pm

Hi there, i became interested in designing a weldless battery system thanks to the genius discussions on this forum in about 2014, and i built a fun prototype which i smashed around and tested at 7.5 C-rate on used lipos. It was robust but it wasn't cheap enough to justify building kits like Vruzend. It was less simple and than their battery grouping design, it was easier and faster, and it wasn't fool proof and sledgehammer resistant:)

One of my buddies said "Finish your weirdy battery project company thing!" last summertime. Benefitting from a fresh mind and more experience of the weldless battery RnD, i recently figured out lots of crafty science to make it cheaply, really safe, pretty, good for all projects, all materials with 20 30 years durability, industrial standard etc. You could bash it with a tennis racket but not a sledgehammer. I am aiming it a solar arrays so i cant divest it until late April :D

I am a digital audio processing algorythms researcher and a general software engineer, i will open source my work and make it printable and for local businesses. I have a scheme/dream to employ 5 DSP engineers for a DSP company i have planned, and some other projects like an itinerant museum truck expo for the third world kids that dont have books n museums in their villages, i aim to match vruzend and give them my tech the moment that i can predict funds to employ 5-8 dsp engineers for a computer company.

What help do i need today?
Please send me contacts, people with yt pages and also advanced engineers who are good at networking, please send their number/email and an intro to:
ZONE23@MAIL.COM i m afan of jehud garcia. :) i would like some endorsement clips and whatever help you can provide, news pages.

Thanks a lot, and to the doubters: who has a weldless battery on their motorbike/ebike, and if so why not? See you!
Last edited by zzoing on Mar 05 2019 10:15pm, edited 1 time in total.

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Re: New weldless battery system crowdfunfing project

Post by Chalo » Mar 05 2019 10:08pm

The battery I built for myself is weldless, because the large format cells I use have threaded posts. That's one of the things I like about it.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

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Re: New weldless battery system crowdfunfing project

Post by zzoing » Mar 05 2019 10:26pm

I hope those batteries you have become ubiquitous i dont know why 18650 and 21700 are in teslas and ebikes. Send me the specifics i want them. Its would be cool to go to india with an empty battery box, find the batteris there and travel on a hero emotorbike.

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Re: New weldless battery system crowdfunfing project

Post by 999zip999 » Mar 06 2019 1:51am

I hate all the connections of 18650 low ah and low voltage cells. How about a 20ah of 5volts or more. Oh 20C ok. Just saying.

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Re: New weldless battery system crowdfunfing project

Post by flippy » Mar 06 2019 2:05am

friction based connections (like fruzens) are highly dangerous in mobile applications with lots of viberations. a single dicky connection can cause major issues like death on a (motor)bike.

the only thing that is even close to "acceptable" is something with heavy duty spring contacts and bolts between both ends pressing down and that amounts to extremely high costs wich means its cheaper and much more reliable just to buy a spot welder.
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Re: New weldless battery system crowdfunfing project

Post by 999zip999 » Mar 06 2019 2:20am

If I had and empty battery box I would take it to Bolivia as they have a big supply of lithium can you smoke lithium AR does lithium just smoke AKA fire. Yes I don't think it's the lithium I kind of bet on Cobalt and magnesium is the best fire starters.

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Re: New weldless battery system crowdfunfing project

Post by zzoing » Mar 06 2019 11:49am

Lithium AR as in Argon? Can you brew tea with it?

You are cruel! "Vruzend, you scary! run run away!" admittedly that is what I thought about putting them on a bike. They are awesome for their initiative. I did clock them again 2 years after to see what their contacts are even like, except that the photos on their sales page have subtly turned every module away from the camera so that you can't see what's inside. LOL! Cmon though! Vruzend was designed in a country where you can legally ride with 4 people and a horse on a scooter :D they don't have the same CE ratings. The vruzend engineer probably has learnt a lot about business and well done for their initiative. Why wouldn't you mount your balls ona vruzend and throttle max power? you are cynical.

How can I get a phone call with Jehud Garcia or someone like that? Mikey or someone a bit presentable and not a weardy beardy programmer with birds nests, can you suggest me some peeps and some numbers please? If you hook me up with some vlog engineers and endorsement testers, a star-treck class battery box will be on sale this April.

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Re: New weldless battery system crowdfunfing project

Post by flippy » Mar 06 2019 3:13pm

vruzend is a flawed concept with no regard for safety. that is simply the end of the story.

anything less then spotwelding is a compromise in safety and reliabliity.
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Re: New weldless battery system crowdfunfing project

Post by john61ct » Mar 06 2019 3:57pm

Always room for innovation.

I have to believe a robust bolt-through design with the right materials could be safe and reliable.

I would certainly want the ability to easily check / monitor and easily swap out weak-link cells as they revealed themselves.

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Re: New weldless battery system crowdfunfing project

Post by liveforphysics » Mar 06 2019 8:03pm

flippy wrote:
Mar 06 2019 3:13pm
vruzend is a flawed concept with no regard for safety. that is simply the end of the story.

anything less then spotwelding is a compromise in safety and reliabliity.
That's almost right, except that I've not yet seen a spot welded pack that was a good example of safety or reliability.

>99% of the solderless battery pack designs suck. >99% of the spotwelded packs suck. 100% of soldered packs suck.

That doesn't mean he couldn't jump into the 1% of good solderless pack designs, but it's non-trivial to design. I would personally throw away spot welded or soldered cylinderical cell packs if I had them laying around, because I've cut open hundreds of 18650 cell bottoms to measure the melted/retracted seperator edge that touches the can floor. If you're spot welding or soldering, your cells are damaged by that process. This means you could get lucky and have a type of damage that doesn't show up as catastrophic failure long term, but it's no guarantee of such luck.

Heat process to bottom of cell = fail IMHO
Last edited by liveforphysics on Mar 07 2019 12:16am, edited 1 time in total.
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Re: New weldless battery system crowdfunfing project

Post by amberwolf » Mar 06 2019 11:54pm

flippy wrote:
Mar 06 2019 3:13pm

anything less then spotwelding is a compromise in safety and reliabliity.
I dunno about that. 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.

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Re: New weldless battery system crowdfunfing project

Post by flippy » Mar 07 2019 5:14am

amberwolf wrote:
Mar 06 2019 11:54pm
flippy wrote:
Mar 06 2019 3:13pm

anything less then spotwelding is a compromise in safety and reliabliity.
I dunno about that. 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.
physical bolts are a massive improvement over friction fit like vruzend, but it is still inherently flawed due to tolerances making poor connections or not enough (or too much) pressure on the cells.

best thing i have ever seen is this thing: https://www.youtube.com/watch?v=tqhJyy2hUdw
i ripped open a cell that i welded with this pulse welder thing and the penetration was bascially perfect. too bad i cant justify the insane cost right now, i found one that was a demo unit and they had a 2k "discount" so i dont really want to know the full retail price....

i still want to investigate the notion of using gas shielding as with TIG based welders with a modified head. but that requires me buying a lathe and for that i first need a bigger workshop.
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Re: New weldless battery system crowdfunfing project

Post by liveforphysics » Mar 07 2019 11:09am

flippy wrote:
Mar 07 2019 5:14am


best thing i have ever seen is this thing: https://www.youtube.com/watch?v=tqhJyy2hUdw
i ripped open a cell that i welded with this pulse welder thing and the penetration was bascially perfect.
If the penetration is making a perfect weld, then the inside surface of the steel of the can in wetted contact with the organic electrolyte reached >1200degC. This does mean you contaminated your electrolyte with byproducts of electrolyte thermal decomposition at best, and at worst thermal damage that mechanically impacts the separator end overlap, which will cause non-uniformity in active material use (premature aging and impedance climb, gassing etc).

Just my $0.02, but there is a reason you don't see spot welds on cylindrical cells outside of Alibaba/ebay and home garage tinkerers.

Some projects are fine if say, 1 in 250 spot welds to the bottom of cans causes some noticeable damage. Some projects have say, 2000 welds per assembly, and no tolerance for tearing it apart to replace the expected 8 damaged cells out of the 2000 weld assembly.

Weldless packs don't have to damage the cell to be assembled. Done right they can have lower contact resistance than bussing you would be capable of spot welding through at home, and they can reduce surface current density from a wider contact area for improved thermal performance. That said, almost everyone's weld-less packs is neither good or done well, but that's a design problem not an intrinsic to the process problem.
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Re: New weldless battery system crowdfunfing project

Post by flippy » Mar 07 2019 12:47pm

you know the bottom of the cell is not touched by anything? if you take one apart you will see the anode is actually welded to the bottom and that is the only thing the bottom touches.

i have had long talks with a few people that actually design 18650 cells from 2 major brands and they unanimously say that welding is the way to go, if you dont overcook the welds then there is zero damage to anything inside the cell. the heating that you constantly bring up is a non-issue. the electrolyte is much more agressive then whatever comes off the weld. also: there is no oxygen to oxidize the metal, so the weld spot on the inside is just fine. there were a bunch of other reasons they tested and bacially welding is the only thing that gave the most consistent results and is the safest in use.

every company that makes batteries with 18650's or other sizes welds the tabs on. i have never seen any high current 18650 inside a product with a friction fit or spring loaded contacts. if you can find a dewalt, matika or even a shitty milfucky with non welded cells i owe you a case of beer.
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Re: New weldless battery system crowdfunfing project

Post by liveforphysics » Mar 07 2019 3:49pm

I don't know how much empty space you think is inside the can, or why its not wetted by electrolyte against that surface, but we can agree to disagree.

I don't know why your friends would recommend boiling it and thermally breaking delicate organic solvents which doesn't require any oxygen to breakdown through thermal decomposition.

Image

The reason this CT scan imaging is nice, is because it shows you not only the separator overhang area, and how it's just a mm or so from where it begins it's job separating anode and cathode foils from contact. That plastic both has a delicate microscopic pore structure it needs to maintain to transport ions while insulating, and it melts around 130-190degC. How much of that little edge overhang do you feel comfortable melting back from the coated foil?

Because these images are of an event that evolved gases, you can see that gas bubble displacing the electrolyte that was wetted against the bottom of the can.
This electrolyte wetting that back wall is thermally sensitive, and undergos a small scall gassing at 70 degC and a macro scale decomposition at 150-250degC depending on carbonate chain lengths and stabilizers. Don't have to believe me, it's been throughly researched for over a decade.

http://m.jes.ecsdl.org/content/165/16/A4051.full

Now you've put reactive decomposition species into your pure cell environment to contaminate reactivate surfaces with materials that aren't storing energy for you, and are an ionic impediment (impacts cell impedance).

If you're making little packs where it doesn't meaningfully matter your decay rate is higher, or fallout rate in mfg is higher, or cell to cell performance is more inconsistent, then hey, it's the cheapest game in town to make something work. If it's an application where quality matters, you find ultrasonic bonds and controled depth laser welds, or hybrid processes.
Last edited by liveforphysics on Mar 07 2019 4:51pm, edited 1 time in total.
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Re: New weldless battery system crowdfunfing project

Post by flippy » Mar 07 2019 4:14pm

in applications where it matters you dont rely on a single cell bond.

and i said it before: in theory you are right. in practice it does not matter one bit.
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Re: New weldless battery system crowdfunfing project

Post by liveforphysics » Mar 07 2019 4:59pm

flippy wrote:
Mar 07 2019 4:14pm
in applications where it matters you dont rely on a single cell bond.

and i said it before: in theory you are right. in practice it does not matter one bit.

More welds on the bottom = more thermal damage

In practice for me, thermodynamics has been painfully reliable and merciless irregardless of my opinions. For this reason I'm happy to agree to disagree with you that it's good practice to raise places on the floor of the can to >1200degC.

Everyone's knee-jerk reaction is to hate on a weld-less design, and point out the shortcommings of the thousands of awful little battery holders in your TV remote controller or toy. This doesn't mean it has to suck, it would be a huge advantage to DIY EV builders to have something that can be assembled and reconfigured without needing specialty equipment. If we encourage and support efforts like that they will be more likely to happen and mature into something good for the community.
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Re: New weldless battery system crowdfunfing project

Post by flippy » Mar 07 2019 5:19pm

the spring loaded contacts in your remote dont have to carry currents in the double digits and have to do this while going 50mph over a cobbled road.
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Re: New weldless battery system crowdfunfing project

Post by liveforphysics » Mar 07 2019 5:23pm

flippy wrote:
Mar 07 2019 5:19pm
the spring loaded contacts in your remote dont have to carry currents in the double digits and have to do this while going 50mph over a cobbled road.
Yep, it's made for the loads a TV remote handles. If it were sized for handling 10's of amps at 10's of G's, it would be needless for a remote.

It still makes it a solvable engineering challenge to make something that works and is lightweight and DIY/kit friendly IMHO.
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Re: New weldless battery system crowdfunfing project

Post by flippy » Mar 07 2019 5:35pm

liveforphysics wrote:
Mar 07 2019 5:23pm
It still makes it a solvable engineering challenge to make something that works and is lightweight and DIY/kit friendly IMHO.
the numbers dont add up for something like that. just the cost in springs and hold down materials far exeeds a roll of nickel and a cheap spot welder for a decently sized battery. not to mention the added size and weight of the system would make it "prohibitive" at best.
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Re: New weldless battery system crowdfunfing project

Post by zzoing » Mar 07 2019 10:01pm

Hey that's very cool. If you re-use a battery box 2-5 times, the cost is 50% - 20% compared to a spot weld battery. The fixed cost of a battery box materials is 15-20 cents for every cell, plus 15 c labour, 10 c tax, 20 c shipping and 10 c for the bms, the rest is things like electricity and automation variable costs, which is about 10 c if it's produced in volume. Ni protected Copper vs Nickel ribbon price is 6.50 $/KG vs 13.00 $/KG.

If the box uses springs, the spring alloy is 2$/KG of fixed cost, that's 1-2 cents for every cell. If you buy a used industrial spring machine for $3000 and produce 1000,000 springs from it, the price is 0.3 c + 0.5 c for every spring.

If you buy a $100 spot welder and $45 of nickel to build 3x 98-cell bike batteries, that costs you $50 dollars for a pack, and if you buy a battery box and use it for 3 groups of cells it costs you $33, plus a saving of 15 hours of labour, plus a resale price for your cells if they don't have soldered caps, which is a rebate of about $50-$100.

So it's economically fine to have a battery box.

Cobblestones is a major stress test for a battery box, indeed. Going up a cobblestone mountain using 20 amps will use about 5A from every cell in a 4s arrangement, and the high quality contacts get warm at about 10-20A in idle conditions. I found that optimal friction contacts can handle cobblestone type stress very easily on a full suspension frame, and i've studied all the safety enhancements that I can add to the box, and there are very many, it's easier than cosmic entropy. i'll write a full safety FAQ a bit later.

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Re: New weldless battery system crowdfunfing project

Post by flippy » Mar 08 2019 4:52am

that is a lot of wishful thinking and a lot of rose-colored glasses calculations.

ps: i am talking about 20A+ per cel.
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Re: New weldless battery system crowdfunfing project

Post by john61ct » Mar 08 2019 2:44pm

Even if it comes out 3-4x the price, being able to just buy the cells and an appropriate box and away you go, will mean a decent market.

The ability to periodically break the pack, test your cells and replace weak ones would be fantastic.

The engineering challenges may be steep, but certainly not impossible, materials keep getting stronger and lighter.

I wish you best of luck, innovators should ignore the "realistic" naysayers, just don't let your dream put you in the poorhouse.

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Re: New weldless battery system crowdfunfing project

Post by spinningmagnets » Mar 08 2019 3:16pm

If the causal readers take anything away from this discussion, I hope it is the fact that the negative end of an 18650/21700 cell is the connection that is the most sensitive to any heat that is used in the connection process . Conquer the negative end, and the positive is easy.

I haven't found any way yet to DIY ultrasonic wire-bonding.

Designs that use a spring on one end seem to insist on using the spring (either coil or leaf) as the conductor. I think there is some potential in having the spring and conductor be two separate elements.

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Re: New weldless battery system crowdfunfing project

Post by flippy » Mar 08 2019 4:29pm

john61ct wrote:
Mar 08 2019 2:44pm
The ability to periodically break the pack, test your cells and replace weak ones would be fantastic.
or just buy proper cells so you never have to.
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