Soldering 18650s

UncleZeb

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Nov 10, 2020
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25
It´s been stated, over and over again ... DO NOT SOLDER 18650s, but seems like almost every battery pack you see on Youtube, by experienced builders, actually solder their packs ??? Very few spot weld, and the majority solder their smaller busbars.
Is soldering okay, if done properly, with the right kit, with no excessive heat ? If so, shouldn´t there be a big warning sign, or atleast
mention of this, if you decide to post a video, soldering busbars on 18650s ? Irresponsible if otherwise ... accident waiting to happen :eek:
 

daromer

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Oct 8, 2016
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Soldering busbars is though not even same as soldering on cells

My oldest are 4 or even 5 years that is in my powerwalls and my oldest soldered in total is 10+ years without issues.

Yes its better to spot weld but it seem to work to solder to based on what many of us have done. With that said its no guarantee it will not burst into flames.. Heck even original builtpacks burst into flames :D
 

UncleZeb

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Nov 10, 2020
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Dr. Dickie

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Sep 23, 2020
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122
My concern with welding (and right now I plan to weld) is, If I don't get enough pressure, and the tip is not clean, in my practice on a nickel strip, it popped right through the nickel strip--only happened once of twice when I was learning. That scared the hell out of me because if I go through the bottom of the cell, I will be running outside with a venting cell.
With soldering, much more control-to me.
I plan to practice a lot more and get reliability to 100%, but welding 2,400 cells, both side, potentially two welds on each cell each side, I gotta be perfect a WHOLE lot.
Does not give me a lot of confidence. But, I am doing this to learn, so...
 

floydR

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Aug 23, 2017
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1,006
if you have extra cells make a small pack, Use the bad or dented cells weld in a well ventilated space, outdoors if you can. I have found that I sometimes flinch before the weld is done and while still in contact with the nickel strip but not firm contact is when the hole is blown in the strip haven't done it to a cell yet. Practice makes perfect or less bad in my case. Yeah i need to practice quite a bit more luckily I have cells from modem packs , and extra m26 cells I sit aside for a 10s40p build. I had started to build But this last year happened. Been retired for 14 months for all 2 months the world has been battling Covid19.
later floyd
 

jonyjoe505

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Feb 28, 2018
Messages
225
With tab welding use the least power that you can get away with. Out of 100's of cells I tab welded(0.15) , never had an incident of the weld going through the nickle strip. If your welding cables are getting too hot, its probably too much power. My tab welder (malectrics) goes up to 99 power, I try to stay under 50 power, when I was using 8 gauge copper clad wire as probe cables I had to use power setting as high as 80 percent. When I replaced my probe cable with 6 gauge pure copper welding wire, I was getting good weld at less then 50 percent power an cables stayed cool.

I use to solder my cells too, but the tab welder is so much quicker, would never go back to soldering.
 

Wolf

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Sep 25, 2018
Messages
1,381
Yep I spot weld all of my packs. I use the Kweld and the consistency is perfect. Did a bunch of practice welds on some old cells turned up the Joules till I blew a hole through a discharged cells bottom,😲 backed up a bit, and ended at 35.9J. Tested tear off strength and it was as good if not better than OE.
Wolf
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Last edited:

deswong

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Jan 20, 2021
Messages
19
Wow - 35J ???

The cables would have jumped heaps when you did the welds!

I spot weld between 15-18J and find that works quite well for me.
 
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