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Discussion Starter · #1 · (Edited)
Hi, I've been studying lithium tech since 2005 and I want to materialize an easy box technology for LiFePO4 and eventually Li-ion cells, to build for small vehicles. It's also a tool to easily re-cycle old car batteries, because the box is compatible with flexible ribbon copper contacts which can wrap over flecks on de-soldered battery terminals.
While this technology isn't applicable to all cells and all chemistries, I'd like to take it as far as possible in EE finesse and erudition of design, with micrographs, asperity surface optimization, tests, EU-US certifications, comprehensive physics data, working with LG/Samsung/Panasonic to find the most reliable cells for this type of system. Price wise it goes from 45 dollars to 125 dollars for a 98 cell box of 18650's, i.e. a complete flat pack DIY battery box will be about $75.

The company can be for profit or non-profit, the priority is not profit, it's technology research, perfect equipment development, low price and good customer service. If you want this technology to become a reality, I'd love your help, please send the project to others. It's going to be free-to-copy for everyone who isn't a multinational company.
 

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Interesting & elegant.

It's missing the thermal conditioning side that's required to justify car/truck EV economics.

Might be ok for personal mobility, village hut "powerwalls" so kids can do homework at night, well pumps, power tools, cellphone chargers, etc, but for automotive, needs a lot more work/thought.
 

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Who is even making 18650s anymore though? Not laptops (who's even buying laptops anymore anyway?).

Soon not even tool battery packs. The new Dewalts are LiPos.

Making your own battery pack can't be cost effective compared to buying something off the shelf.

Custom-sized batteries are alright for hobbyists, but, by the time you scale them, you've just created a less cost effective way of making a battery pack. A hobbyist wouldn't really care about the extra time it takes to spot weld a battery pack, it's just not that much time.

Looks good, and if cost was low enough I would use this, but, I don't know how much market potential there is for these.

Anyway, decent hobby idea. Not so sure about business idea.
 

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Discussion Starter · #5 · (Edited)
Custom-sized batteries are alright for hobbyists, but, by the time you scale them, you've just created a less cost effective way of making a battery pack. A hobbyist wouldn't really care about the extra time it takes to spot weld a battery pack, it's just not that much time.
Hey, thanks for your comments.

Car batteries can take side-impacts at 90kph with the user sitting just above the lithium ions, hence the design complexity... Actually I was thinking a lot about rickshaws when I developed this, because some places have 20 times higher air pollution than Los Angeles / Paris, so i'm quite motivated to help people from those regions.

18650's are still the cheapest and most produced, and most sold battery format. The box performs a bit higher if converted to 21700, i.e. 75 amps minimum.

Buying a 3rd party spot welded pack is very expensive, it's 2x times the cost of bare cells,so $250 extra for a 1kw battery. This tech would save cash first time round, and it's re-usable and re-sellable, so the second / third / fourth use is free, and the box can be re-sold.

A spot welder costs 50-150 dollars, the nickel is 9 times more expensive than copper for the same level of performance, and nickel is 4x less ampacity, it's just that copper is difficult to weld.

Yes it's only designed for a bit of air cooling at the moment, it would be advantageous for non-steel vehicles less than 500kg, motorbikes, golf buggies, boats, quads.
 

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There are other no-spot-welding-required battery building kits out there, but yours has the advantage that the enclosure and BMS mounting is already a part of the design. If I were you I would just start a small online shop with open-source BOM and STLs, and collect revenue selling the ready-to-build kits with injection molded parts.
 

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In the same chemical, prismatic lifepo4 batteries are more thermally stable than cylindrical lithium batteries,
Most Ev use NMC,NCA and the shape of the batteries doesn't make a bit of difference to the flammability of the batteries. It all comes down to the chemical makeup of the cell.
The article linked has a couple false statements. lets examine them.
"The Life Span
Overall, due to the different manufacturing processes, the cylindrical type will have slightly more cycles than the prismatic LiFePO4 cell."
"Therefore, the cylindrical shape is also the shape of lithium batteries with the longest history and the largest size."
headway 38120 2000cycles 1C 80%DOD
YHKAM 60290 2000 cycles capacity retention rate 80% http://yinhene.com/product/showproduct.php?id=30&lang=en
The YHKAM 60290 90Ah cell is the largest LiFePO4 cylindrical cell I know of.
On the Prismatic side TS-LYP1000AHC 1000Ah Thunder Sky Winston LiFePO4 Battery WB-LYP1000AHAC with life cycle @80% DOD ≥5000 cycles.
So two things stated in article are false according to my research. Most of the article is fairly accurate But no where does it mention "thermally stable"
later floyd
 

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Most Ev use NMC,NCA and the shape of the batteries doesn't make a bit of difference to the flammability of the batteries. It all comes down to the chemical makeup of the cell.
The article linked has a couple false statements. lets examine them.
"The Life Span
Overall, due to the different manufacturing processes, the cylindrical type will have slightly more cycles than the prismatic LiFePO4 cell."
"Therefore, the cylindrical shape is also the shape of lithium batteries with the longest history and the largest size."
headway 38120 2000cycles 1C 80%DOD
YHKAM 60290 2000 cycles capacity retention rate 80% Cylindrical high-energy lithium iron phosphate power battery-湘潭银河新能源有限公司
The YHKAM 60290 90Ah cell is the largest LiFePO4 cylindrical cell I know of.
On the Prismatic side TS-LYP1000AHC 1000Ah Thunder Sky Winston LiFePO4 Battery WB-LYP1000AHAC with life cycle @80% DOD ≥5000 cycles.
So two things stated in article are false according to my research. Most of the article is fairly accurate But no where does it mention "thermally stable"
later floyd
I don't think you can use a casual example to prove your point. Especially the Winston battery you're using, it's a very good battery. But the cylindrical battery example...I don't comment. For comparison, it is better to compare with batteries of the same level, which will be more convincing, otherwise, it is just a smoke bomb. Let me give a simple example. Tesla's batteries use NCA raw materials (now LiFePO4 is also added). Can you think that Tesla's LiFePO4 batteries only have 2000 cycles?
 

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I don't think you can use a casual example to prove your point. Especially the Winston battery you're using, it's a very good battery. But the cylindrical battery example...I don't comment. For comparison, it is better to compare with batteries of the same level, which will be more convincing, otherwise, it is just a smoke bomb. Let me give a simple example. Tesla's batteries use NCA raw materials (now LiFePO4 is also added). Can you think that Tesla's LiFePO4 batteries only have 2000 cycles?
Man these bots are annoying.
 

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note the Tesla batteries are stabilized in potting and use welded fuses for connection. having a spring in your contact system is great for tolerance, but not so great for a dynamic system. I would suggest a lot of vibration testing before advocating use in a mobile environment.
 

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Discussion Starter · #18 ·
note the Tesla batteries are stabilized in potting and use welded fuses for connection. having a spring in your contact system is great for tolerance, but not so great for a dynamic system. I would suggest a lot of vibration testing before advocating use in a mobile environment.
Yes I love to know very precisely what the physics and statistics of these designs are, so the company will be strongly based on a diversity of precise test rigs and science research.

Generally, li-ion safety has been on the rise, although great caution is still necessary. These days all cylindrical batteries from the major companies include a thin layer of foam in the electrolyte which lets the ions travel through freely unless the temperature rises above ~85 degrees Celsius, then the foam melts into a solid barrier which isolates the jelly roll by causing a physical barrier where the electrolyte is. Tesla uses these, and they cause lithium to combust more like paraffin than like pure magnesium, which is what it used to. It makes lithium a lot safer than it was in the early 2010's, although it's possible to have lithium fires, i.e. the boat with 100 million of luxury cars which completely burnt in February 2022 and the Tesla power station in Australia which also caught fire dramatically. I'm ensuring that the battery box has optimum insulation and best gentle treatment of the batteries.

Sometimes we focus too much on fire safety and forget that the WHO estimates that 4 million people every year perish due to air quality issues, that's about 2000 in a city like L.A. and 20,000 yearly in a city like New Delhi, mostly from cancer and cardiac issues, so to help rapid adoption of lithium can only be a good way forward.
 

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Yes I love to know very precisely what the physics and statistics of these designs are, so the company will be strongly based on a diversity of precise test rigs and science research.

Generally, li-ion safety has been on the rise, although great caution is still necessary. These days all cylindrical batteries from the major companies include a thin layer of foam in the electrolyte which lets the ions travel through freely unless the temperature rises above ~85 degrees Celsius, then the foam melts into a solid barrier which isolates the jelly roll by causing a physical barrier where the electrolyte is. Tesla uses these, and they cause lithium to combust more like paraffin than like pure magnesium, which is what it used to. It makes lithium a lot safer than it was in the early 2010's, although it's possible to have lithium fires, i.e. the boat with 100 million of luxury cars which completely burnt in February 2022 and the Tesla power station in Australia which also caught fire dramatically. I'm ensuring that the battery box has optimum insulation and best gentle treatment of the batteries.

Sometimes we focus too much on fire safety and forget that the WHO estimates that 4 million people every year perish due to air quality issues, that's about 2000 in a city like L.A. and 20,000 yearly in a city like New Delhi, mostly from cancer and cardiac issues, so to help rapid adoption of lithium can only be a good way forward.
Maybe I am missing something, but I believe there is no Lithium to combust in any of those cells. There is simply no metallic Lithium in the cells. What combusts is the electrolyte, and the complexity is around the fact that even after the fire is extinguished, electrical / thermal causes aren't eliminated thus the whole thing reignites until all of the electrolyte is burned out.
 

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Having lit off a cell by inadvertently puncturing it during harvesting, I can tell you that it lights off nothing like paraffin and goes off by emitting a pressurized jet of combustion like a bottle rocket.

In fact, I know for a fact that they do go all over the cabin like little rockets once the fire compromises the vehicle floor.

Paraffin? Don't think so.
 
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