18650 spot welding -how to- ULTIMATE REPOSITORY

[limpsilver]

Hi.
I want to build a 20s6p with 25R cell.
As I want 25A/cell (150A max battery) for 10sec max, can I use this kind of nickel?
http://fr.aliexpress.com/item/FREE-SHIPPING-High-Quality-Pure-Nickel-Plate-Strap-Strip-Sheets-99-96-for-battery-spot/2054948107.html
If I double it, will it be ok?
Thanks

 

[TheBeastie]

Came across this video on 18650s and how they internally auto shut down/physically disconnect if excessive gases build up internally..
Sometimes I think about the engineering levels 18650 designers must go to to ensure their cells are safe and this video helps reflect my assumptions.. Have to remember 18650s were designed with the mind frame of theoretically millions of children around the world with 18650s inside their laptops placing their laptops under their mattress/bed before going to sleep each night etc..

https://www.youtube.com/watch?v=1w3Tv1Jg0ps&feature=youtu.be

[youtube]1w3Tv1Jg0ps[/youtube]

 

[flippy]

Hi.
I want to build a 20s6p with 25R cell.
As I want 25A/cell (150A max battery) for 10sec max, can I use this kind of nickel?
http://fr.aliexpress.com/item/FREE-SHIPPING-High-Quality-Pure-Nickel-Plate-Strap-Strip-Sheets-99-96-for-battery-spot/2054948107.html
If I double it, will it be ok?
Thanks

No. You need at least 0.3mm

 

[tomjasz]

I have a new 709A that died on the first weld. I also have the parts they sent me including a new PCB. I'd sell it minus the welding probes for the price of a new PCB $75 plus shipping. Include original PCB and new PCB.

There's no sign of damage or burned out parts.

 

[Overclocker]

i just wired up a 3-cell pack to power my JP Welder. i wonder what the allowable voltage range is...

 

[riba2233]

For logic supply? 9-15 Vdc

 

[Overclocker]

For logic supply? 9-15 Vdc

yes. thanks riba. i find this more convenient than having a 12v adapter plugged into AC

 

[riba2233]

Yep, it's great to have portable solution

 

[limpsilver]

Hi.
I want to build a 20s6p with 25R cell.
As I want 25A/cell (150A max battery) for 10sec max, can I use this kind of nickel?
http://fr.aliexpress.com/item/FREE-SHIPPING-High-Quality-Pure-Nickel-Plate-Strap-Strip-Sheets-99-96-for-battery-spot/2054948107.html
If I double it, will it be ok?
Thanks

No. You need at least 0.3mm

yes, I will do it a different way :

With 1.5mm² or 2.5mm² wire for series and classic 0.15mm nickel for parallel.

 

[Skrzypas]

Hi.
I want to build a 20s6p with 25R cell.
As I want 25A/cell (150A max battery) for 10sec max, can I use this kind of nickel?
http://fr.aliexpress.com/item/FREE-SHIPPING-High-Quality-Pure-Nickel-Plate-Strap-Strip-Sheets-99-96-for-battery-spot/2054948107.html
If I double it, will it be ok?
Thanks

No. You need at least 0.3mm

yes, I will do it a different way :

With 1.5mm² or 2.5mm² wire for series and classic 0.15mm nickel for parallel.

Although this design seems to be ideal, it isn't. It was discussed also in this thread before. Shortly speaking:

1. The current from each cell must go through a path nickel - copper - nickel, so it meets two additional solder joints on its way.

2. The current from side cells passes through one nickel strip, but the center cells give half current to the left and half to the right strip. This means that during peaks, the cells inside the pack will undergo higher discharge currents.

 

[limpsilver]

Ok
How can I do it better (with 25A per cell peaks)?

 

[pguk]

As regards paths of resistance, I can see that there are differences due to different lengths of nickel which each cell has to push current through.

But if we think about what happens to a parallel cell block at discharge - voltage across all cells has to be equal all the time. So if, as you suggest, centre cells have ability to supply more current than the outer cells, then current from the outer cells will have to flow into those inner cells because their discharge curves are tied together with nickel. Thus, state of charge of parrallel group remains equal over full discharge curve.

 

[riba2233]

Those are minor problems, in reality it's not that bad, especially because both nickel and copper are supersized, and solder spots are very reliable.

 

[agniusm]

Have a couple of questions. Would it be possible to weld nickel strip .15 - .03 to larger copper piece say 15x15x15? I see Riba is back, glad that you made out of the hospital alright and back on forums, and the question is for you or anyone with the answer. Would JP spotwelder would be able to weld above mentioned situation? Will these welders continue to be made. Thank you all

 

[riba2233]

Thanks!

I've mostly manged to weld 0.1 mm nickel to 0.6 mm copper plate, but maybe with diode mod and stronger battery, you could use thicker nickel strip.

 

[limpsilver]

Maybe this link should be added to the first post. It is way cheaper than other links.

Where should I get enormous battery shrink wrap?
Here https://bmsbattery.com/shrink-tube/658-one-meter-pvc-heat-shrink-tube-big-shrink-tube.html#/414-half_perimetermm-238

 

[jmz]

Maybe this link should be added to the first post. It is way cheaper than other links.

Where should I get enormous battery shrink wrap?
Here https://bmsbattery.com/shrink-tube/658-one-meter-pvc-heat-shrink-tube-big-shrink-tube.html#/414-half_perimetermm-238

How should you size this? What margin would you add to a pack circumference?

 

[limpsilver]

Is it safe to put foam on the side of the pack ? I mean cells will get very hot in my pack (25A/10C peak per cell), no risk of fire?
My foam is this one : http://www.hobbyking.com/hobbyking/store/__86289__Aero_modelling_Foam_Board_3mm_x_500mm_x_700mm_White_EU_Warehouse_.html

How should you size this? What margin would you add to a pack circumference?

You can find the answers here http://www.ebikeschool.com/how-to-build-a-diy-electric-bicycle-lithium-battery-from-18650-cells/

 

[kdog]

An excellent article on spot welding
http://www.amadamiyachi.com/servlet/servlet.FileDownload?

 

[riba2233]

An excellent article on spot welding
http://www.amadamiyachi.com/servlet/servlet.FileDownload?

Link doesn't work...

 

[ridethelightning]

http://www.amadamiyachi.com/servlet/servlet.FileDownload?retURL=%2Fapex%2Feducationalresources_fundamentals&file=01530000000Jybm

i think its this one, try again

 

[riba2233]

Yeah I've already found it

But that's it, thanks!

 

[LiFeCycle]

Hi

Doing some research about nickel vs copper strips. Seems that although coppers higher electrical conductivity would be desirable, it's thermal conductivity makes it difficult to spot weld.

And for some reason copper/nickel mixtures have worse conductivity than pure nickel.

So i wondered whether there might be a multi-layered product available that would have the best of both worlds. I found this 'SigmaClad' product which appears to be designed for this exact purposes. Couldn't find anything on ES about this yet, so here is a link to the white paper. http://www.emsclad.com/fileadmin/user_upload/Divisions/EMS/SigmaClad_White_Paper.pdf

Has anyone used it or anything like it to build a pack?

 

[tomjasz]

The subject of copper has come up dozens of times and the discussion always comes back to pure nickel. While ES has been the source of many great discoveries I think this has horse has been beaten to a pulp. Nickel just works.

 

[PaulD]

The subject of copper has come up dozens of times and the discussion always comes back to pure nickel. While ES has been the source of many great discoveries I think this has horse has been beaten to a pulp. Nickel just works.

Has anyone considered brass?
Roughly the same conductivity as nickel .. Corrosion resistant and cheap.
Edit: maybe the thermal conductivity is too high.. More than nickel but much less than copper.

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