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### 18650 spot welding -how to- ULTIMATE REPOSITORY

Posted: Mar 24 2015 12:13am
Warning: Just a single 18650 cell has the potential to start a fire in your home / workplace. Building a battery is a very dangerous task that should only be done by an expert in electricity and electronics.

I made this thread in order to leave things crystal clear for the future.
I will update the head post with all the info required, asked, debated, requested in any other ES place.

I start with a small piece of info data I calculated as exactly as I could as deep research, I added to the data my own heat test about the max Amps that pure nickel and nickel plated steel strips stand in the right conductivity range.

Copper, nickel and steel amperage table (insulated)

The table take into account each material own resistivity, heat dissipation properties, average length for 18650 uses, ambience of work (insulated, in groups, in contact with heat generators) and measurements.

As the amount of heat released from a conductor is proportional to the square of the current (resistive heating--> Heat = amperes^2 * electrical resistance) the heat starts to increase exponentially. Beyond poor / bad values you could have melted insulators in high exterior temperatures / poor battery cooling, given the risk it suppose.

Below the optimal values the nickel stays mild and close to ambience temperature, so the efficiency is optimal under those current levels and you can measure with precision the heat generated exclusively by the cells.
Cu, Ni, Steel efficiency chart.png (43.32 KiB) Viewed 57691 times
As nickel and nickel plated steel are extremely difficult to difference at sight, there are an easy homemade test that could be done in order to check if you have one or another.
Take a strip sample and polish / scratch with a dremel tool or simply with a knife on a small area, and put into salty water for 12h to 24h. This is how it looks.
The upper samples are pure nickel ones, and the bottom ones are nickel plated steel. The corrosion is clearly shown. This doesn't discard the steel for welding purposes, if the strips are in good condition would be enough for batteries that will be used in dry environments.

Pure nickel and nickel plated steel corrosion test
You can watch a video of the test -------> http://www.youtube.com/watch?v=w40t0RxQd3Q

Where should I get authentic cells from Europe?

http://endless-sphere.com/forums/viewto ... 31&t=61608
http://eu.nkon.nl/
https://www.akkuteile.de/

Where should I get authentic cells from USA?

http://endless-sphere.com/forums/viewto ... 31&t=61608

Where should I get authentic cells from any other place?

e.g. Samsung 26F http://aliexpress.com/item/10pcs-lot-Or ... dVersion=1

http://endless-sphere.com/forums/viewto ... 31&t=61608

Where should I get a Spot Welding machine from Europe?

Low cost classic:(tested) http://aliexpress.com/item/Hand-held-Sp ... dVersion=1

Low cost 788+:(tested by other users) http://www.aliexpress.com/item/DHL-FEDE ... dVersion=1
- Review - : http://syonyk.blogspot.com.es/2015/05/o ... elder.html
- Failure and repair of triacs - : http://syonyk.blogspot.com.es/2015/05/s ... epair.html

Recommended: JP spot welder http://endless-sphere.com/forums/viewto ... 31&t=68865

Recommended: Sunko 709A upgraded (tested) http://www.aliexpress.com/store/product ... 32700.html

Make your own!: Arduino spot welder controller / solid state relay http://www.avdweb.nl/arduino/hardware-i ... lay-dimmer

Make your own! (2): 6pence Resistance Spot Welder (brain board) https://endless-sphere.com/forums/viewt ... 0#p1196210

Where should I get a Spot Welding machine from USA?

Low cost:

Recommended: http://www.ebay.com/itm/110V-Hobby-Mini ... 1610987714

Recommended: JP spot welder http://endless-sphere.com/forums/viewto ... 31&t=68865

Recommended: Sunko 709A upgraded (tested) http://www.aliexpress.com/store/product ... 32700.html

Make your own!: Arduino spot welder controller / solid state relay http://www.avdweb.nl/arduino/hardware-i ... lay-dimmer

Make your own! (2): 6pence Resistance Spot Welder (brain board) https://endless-sphere.com/forums/viewt ... 0#p1196210

Where should I get a Spot Welding machine from any other place?

Low cost: http://aliexpress.com/item/Hand-held-Sp ... dVersion=1

Low cost 788+:(tested by other users) http://www.aliexpress.com/item/DHL-FEDE ... dVersion=1

Recommended: JP spot welder http://endless-sphere.com/forums/viewto ... 31&t=68865

Recommended: Sunko 709A upgraded (tested) http://www.aliexpress.com/store/product ... 32700.html

Where should I get nickel strips?

Nickel strips: (10 meters)(tested) http://aliexpress.com/item/Free-shippin ... dVersion=1

Nickel strips: (~100 meters (1Kg)) http://aliexpress.com/store/product/Fre ... 69234.html

Nickel strips: (~100 meters (1Kg)(tested)) http://aliexpress.com/item/FREE-SHIPPIN ... 48107.html

Nickel plated STEEL strips (tested): http://aliexpress.com/item/100pcs-Nicke ... Title=true

Where should I get a BMS?

http://liionbms.com/php/bms_options.php

Where should I get enormous battery shrink wrap?

http://stores.ebay.com/Atop-Authentic-A ... 34.c0.m322

http://aliexpress.com/store/group/PVC-h ... 60614.html

Paralleling, serialing, balancing, BMS

http://liionbms.com/php/white_papers.php

Battery Deterioration

http://endless-sphere.com/w/index.php?t ... erioration

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Self adhesive "fish paper" insulation sheets from ebay seller supowerbattery111
"8x Fish Adhesive Paper Electrical battery Pack Insulating"

"Spot Welding Copper Strips to 18650 Battery Cells"
https://endless-sphere.com/forums/viewt ... 14&t=84680

"Brass for spot-welding 18650 parallel cell groups?"
https://endless-sphere.com/forums/viewt ... 14&t=85059

Supplier of honeycomb configuration plastic cell holders, plus 30-degree angled nickel bus-strips
https://www.aliexpress.com/item/18650-b ... 20653.html

### Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Posted: Mar 24 2015 12:17am
Thx

### Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Posted: Apr 24 2015 12:03pm
Thank you Nobuo.

This deserves to be considered for sticky status.

### Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Posted: Apr 24 2015 2:29pm
Thx

### Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Posted: Apr 24 2015 6:56pm
silentflight wrote:Thank you Nobuo.

This deserves to be considered for sticky status.
You are welcome, any info do you think it would be essential can be added.

Maybe too soon for that, but I will be improving this util get the worth

### Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Posted: Apr 24 2015 7:23pm
Thank you for this nice copilation

### Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Posted: Apr 25 2015 12:40am
Good but far from ULTIMATE
Like to your signature i want add ** Lithium + Chemical-Additives + Air = ZERO Fire **

The maxAmps table have absolute no meaning without knowing the lenght from the wire/strip.
Also the difference from pure nickel to plated steel is between 10-20% and not 50%

For buying new cells best can do is make account here http://www.alibaba.com/trade/search?fsb ... 50+samsung
Write every "Verified Supplier" a inquery with shipping cost from the cells u want than chose the cheapest.

With all new cells and a little care no BMS is required for li-ion 18650.

There are DIY spot welder on E-S easy to do in a few hours for <\$30 with car battery.

### Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Posted: Apr 25 2015 5:25am
If you are in Europe, getting cells form overseas makes no sense.
Just check out http://www.nkon.nl
Cells are original and at your door after 2-3 days.

You could add this to the top

### Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Posted: Apr 25 2015 2:01pm
DrKraut wrote:If you are in Europe, getting cells form overseas makes no sense.
Just check out http://www.nkon.nl
Cells are original and at your door after 2-3 days.

You could add this to the top
Yes true, now tumich ES user is indeed the best supplier in Europe, I will add that source.

Thanks!

### Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Posted: Apr 25 2015 2:32pm
zener wrote:Good but far from ULTIMATE
Like to your signature i want add ** Lithium + Chemical-Additives + Air = ZERO Fire **

The maxAmps table have absolute no meaning without knowing the lenght from the wire/strip.
Also the difference from pure nickel to plated steel is between 10-20% and not 50%

For buying new cells best can do is make account here http://www.alibaba.com/trade/search?fsb ... 50+samsung
Write every "Verified Supplier" a inquery with shipping cost from the cells u want than chose the cheapest.

With all new cells and a little care no BMS is required for li-ion 18650.

There are DIY spot welder on E-S easy to do in a few hours for <\$30 with car battery.
Thank you for the appreciations, I will add that to my signature

The table is as good as I could made with deep researching of the latest data. I'm completely agree that the length make a difference, the data counts that the length is very similar on the builds, between 8mm and 30mm are the very most of the nickel conductors lenght in 18650 packs.

All the Steel alloys known has between 10x (for carbon steel) to 20x more electrical resistivity than copper. The steel used in nickel tinned steel strips use to be carbon steel with a very thin tin (40 micrometers it is the common) so that is counted together with Amps / heat tests I made between pure nickel and steel for the same section size.

So the difference from pure nickel to plated steel is not 10-20% and neither 50%, in fact is a 100% you can take this table as a slightly reference, http://en.wikipedia.org/wiki/Electrical ... nductivity

Thanks for the alibaba searching tip, I will add

### Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Posted: Apr 25 2015 3:05pm
Nobuo wrote:
zener wrote:Good but far from ULTIMATE
Like to your signature i want add ** Lithium + Chemical-Additives + Air = ZERO Fire **

The maxAmps table have absolute no meaning without knowing the lenght from the wire/strip.
Also the difference from pure nickel to plated steel is between 10-20% and not 50%

For buying new cells best can do is make account here http://www.alibaba.com/trade/search?fsb ... 50+samsung
Write every "Verified Supplier" a inquery with shipping cost from the cells u want than chose the cheapest.

With all new cells and a little care no BMS is required for li-ion 18650.

There are DIY spot welder on E-S easy to do in a few hours for <\$30 with car battery.
Thank you for the appreciations, I will add that to my signature

The table is as good as I could made with deep researching of the latest data. I'm completely agree that the length make a difference, the data counts that the length is very similar on the builds, between 8mm and 30mm are the very most of the nickel conductors lenght in 18650 packs.

All the Steel alloys known has between 10x (for carbon steel) to 20x more electrical resistivity than copper. The steel used in nickel tinned steel strips use to be carbon steel with a very thin tin (40 micrometers it is the common) so that is counted together with Amps / heat tests I made between pure nickel and steel for the same section size.

So the difference from pure nickel to plated steel is not 10-20% and neither 50%, in fact is a 100% you can take this table as a slightly reference, http://en.wikipedia.org/wiki/Electrical ... nductivity

Thanks for the alibaba searching tip, I will add
Signature looks now much more EV friendly.

For a rough comparison its sufficent without lenght.

After a long review the steel strip resistivity makes sense.

### Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Posted: Apr 26 2015 1:29am
I add to the spot welders buying tips the homemade "JP spot welder" with the permission of riba2233

### Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Posted: Apr 26 2015 4:04am
Thank you!

### Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Posted: Apr 26 2015 5:07am
awesome thread.... should be more like it.

### Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Posted: Apr 27 2015 4:05pm
For those who want pure nickel, I could speak with the last vendor I bought the verified 1.022Kg, and he just make a special price for 48hours. A really really good deal, these are the specs avaliable: (it is also linked on the repository, but the price could change)
0.05 x 10 mm
0.07 x 3 mm
0.08 x 3 mm
0.08 x 4 mm
0.1 x 3 mm
0.1 x 4 mm
0.1 x 5 mm
0.1 x 6 mm
0.1 x 7 mm
0.1 x 8 mm
0.12 x 6 mm
0.15 x 8 mm
0.15 x 6 mm

http://www.aliexpress.com/item/FREE-SHI ... rue#extend

Tests are on the first post

### Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Posted: May 11 2015 6:59am
Hey nobuo, what parameters were you using to determine the current carrying capacity for the strips, I mean what is the limiting factor?
I tested a strip of NPS aprox 60x7x0.15mm at 4amps with no perceptible heat build up. This was in open air not insulated at all. I think it could have had a 1-2 more before getting even slightly warm.
This is a great thread you started
Cheers

### Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Posted: May 11 2015 7:51am
You calculate cross section, divide it by 4, and then you have equivalent copper cross section, and you can look up at tables for current capabilities.

### Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Posted: May 11 2015 10:33am
All the values on the table are the maximum amps before the nickel starts to saturate and getting warm.
The table take into account each material own resistivity, heat dissipation properties, average length for 18650 uses, and measurements.

As the amount of heat released from a conductor is proportional to the square of the current (resistive heating--> Heat = amperes^2 * electrical resistance) the heat starts to increase exponentially. So beyond those values is when the nickel increases the heat noticeably for any small current increase.

Below the values the nickel stays mild and close to ambience temperature, so the efficiency is optimal under those current values and you can measure with precision the heat generated exclusively by the cells.

remember that when the nickel is in real use, although is not really insulated, it works inside an insulating wrapping, this is also taken into account

Thank You, I hope we can make this greater, useful and precise for your future projects.

Cheers

### Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Posted: May 13 2015 6:54pm
Thank you Nobuo,

Just FYI, I've bought some enormous PVC battery shrink wrap in the US from these guys in Northern California. They have a nice formula for converting from battery pack circumference to the shrink wrap width, and they sell by the foot, which is nice. I've bought their 12.2" width shrink wrap.

The formula they give is: PVC Width > = ( the circumference of your pack ) / 2 + 5 mm

https://www.all-battery.com/pvcshrinkwrap.aspx

Best,
Kent

### Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Posted: May 14 2015 3:11am
Another great place for heatshrinks:

http://stores.ebay.com/Atop-Authentic-A ... 34.c0.m322

All sizes and colors you need.

### Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Posted: May 14 2015 12:52pm
riba2233 wrote:Another great place for heatshrinks:

http://stores.ebay.com/Atop-Authentic-A ... 34.c0.m322

All sizes and colors you need.
Really impressive, different colours and sizes. thanks! added!

### Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Posted: May 14 2015 10:26pm
I think you owe it to the thread to add a do it yourself 800 watt second capacitor dischage available from Fritz right here, http://frikkieg.blogspot.com I made one for about \$600 ready to start welding. This is a over 10,000 amp Dual pulse capacitor discharge welder that is voltage adjustable to 23.2 volts and has separate fully adjustable first and second pulses for the ultimate in versatility. To buy a Sunstone CD welder That is only 200 watt seconds will cost \$3875 from Power Stream http://www.powerstream.com/spot-welder.htm

Here is my build, http://endless-sphere.com/forums/viewto ... =1&t=68521

You might find a welder that will spot weld batteries but you will not find a better battery spot welder.

Tom

### Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Posted: May 15 2015 3:38am
I think it's an overkill and waste of money if you are only going to weld 18650 cells. It's 600\$ (with electrodes?) and you still have to invest your time by assembling it? And it's way to powerful.

### Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Posted: May 15 2015 5:54pm
riba2233 wrote:I think it's an overkill and waste of money if you are only going to weld 18650 cells. It's 600\$ (with electrodes?) and you still have to invest your time by assembling it? And it's way to powerful.
Seeing how the title states "Ultimate Repository" you think you would have the ultimate hobby spot welder listed and not just a battery short circuit device. As far as a waste of money the same could be said about yours since it's only good for one thing while this one will work with anything now or coming in the future of this EVER changing battery world and weld any material I want to attach. When in the hell would anyone on this site be upset with "too powerful?" That is never used in a sentence on this forum!!! As far as price yours will cost \$350 U.S. With 2 batteries and a power supply and then you still need to buy a battery charger for the car batteries. Some people don't mind paying for and/or building a high quality tool that will last for many years through the evolutions of things to come and not just get by with a toy by comparison.

I'm not saying yours isn't adequate.......it's just not the ultimate!

Tom

### Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Posted: May 16 2015 4:01am
litespeed wrote: Seeing how the title states "Ultimate Repository" you think you would have the ultimate hobby spot welder listed and not just a battery short circuit device. As far as a waste of money the same could be said about yours since it's only good for one thing while this one will work with anything now or coming in the future of this EVER changing battery world and weld any material I want to attach. When in the hell would anyone on this site be upset with "too powerful?" That is never used in a sentence on this forum!!! As far as price yours will cost \$350 U.S. With 2 batteries and a power supply and then you still need to buy a battery charger for the car batteries. Some people don't mind paying for and/or building a high quality tool that will last for many years through the evolutions of things to come and not just get by with a toy by comparison.

I'm not saying yours isn't adequate.......it's just not the ultimate!

Tom
There's no need for tone like that. I just made a few points and asked a few questions, but guess you got a bit to upset to answer them, and just started bashing.
Please don't lie, my welder wont cost 350\$. And while it might be "just battery short circuit device" (LOL), what is yours, capacitor short circuit device? What do you think, which one has nicer pulse shape and more controllable pulse?

So, my point was that this is ultimate 18650 spot welding repository, and your welder is total overkill for 18650 cells. That's because you can't weld material that is too thick for 18650 cell, because you will destroy them. So, if you want to weld 18650 cells (not some thick sheet metal), your welder is too expensive, and demands labor and skills. Especially for someone who just wants to make a pack for himself.
I also didn't mention my spot welder, let alone compare it to yours, because they are whole different leagues.

So, ease up on your tone, and contribute to the topic by answering questions you have been asked. Bashing someone with lies and ad hominem is not the right way to contribute on forum. Thanks.