18650 spotweld vs. solder steel vs nickel rust confusion

I accidentally ordered 50m nickel plated steel and I thought that if spotwelding it would create corrosion problems then I go for soldering. I had some nickel strips here - which were supposed to be pure nickel - I wanted to do some test solderings to find out how viable it is and when I did a pull test it came off very easily but not because it was a bad solder but because a thin layer remained on the cell I guess this was the nickel coat so it turns out that it wasnt pure nickel. So conclusion is that one can only spotweld nickel plated steel because if the plate gets too hot it comes off easily. So weld is the only option for nickel plate.

Now here comes a techincal question. The case of the battery is steel anyway. So what does it matter if I weld nickel or steel to it, the battery side will rot anyway if it is welded onto because the weld breaks the integrity of the cell case's rust protection coating. I am interested in this from a purely corrosion standpoint I know nickel has better conductivity and all. I just wanna know whether welding pure nickel is also better from a corrosion standpoint or when it comes to corrosion pure nickel doesnt make a difference anyway for the cell wall is steel anyway. I just wanna know if it will be so bad if I use this 50 meter up and spotweld the battery with these or should I go for the pure nickel at all costs? Conductivity is not a great issue it will be quite a large battery for the application. What I wanna know is the corrosion question. The bottomline question; why bother with pure nickel if the spotweld will rust anyway because the battery is made from steel? (Not concerning the conductivity issue only the rust issue).


Private musings

(Also it seems that pure nickel is the only solderable thing unless you wanna flood the nickel plated strip with solder so it is a solid bond but that will overheat the cell for sure so soldering nickel plated is an absolute no go either you have a shitty bond and a cool battery or a solid bond but an ovetheated battery, so pure strips are the only solderable stuff in town. However if one solders pure nickel then the integrity of the cell will fully remain and it will never ever corrode because the soldering didnt mess with the case of the cell unlike welding. So it seems to me that soldering nickel or even copper - if only copper strip was available - is the only rust free solution in town. Maybe spotweld is not king after all? I start to think that spotweld is only for the industry and mass production, but for us DIY heckers soldering is much better especailly because then you can also solder copper strips for a far superior conductivity. And it's such a myth that it overheats the cell it overheats nothing it can be done away with under a second. Just imagine soldering copper strips no rust no poor conductivity and no overheat if you are a clever solderer. Seems like a win win win...I think properly soldering copper is the greatest solution to building packs from flathead cells. I used to be an avid spotweld advocate but my world is absolutely shattered now. I am leaning towards soldering now.)




Thanks

what does shatteted mean?

Soldering can easily damage the internals if these cylindrical batteries via overheating

one second is a very long time

I guess you could have found out by looking at the queRTy keyboard...

I once managed to puncture a hole in a cell cause of a shitty spotwelder. I got panicked when I saw the electrolyte bubbling from under the nickel strip I tore the pack apart immediately and wanted to patch it up with solder. There must have been some oxide layer on them cause it kinda refused the tin. So I went at it with several attempts. To the extent
that the electrolyte started to boil I managed to plug the hole the problem was that at this point the electrolyte was gushing up and the tin didnt have enough time to clot. So the electrolyte always blew the hole open. Eventually I put the cell in a frozen peanut bag and I could seal the deal so to speak cause the electrolyte cooled down no longer recreating the hole. I thought this cell must be finished. I put it in the capacity mater and it was perfect even after some electrolyte loss. I put it back in the pack spotwelding around the tin patch. No complaints so far. The pack is healthy still. If a cell can endure this kinda torture I dont think it couldnt handle a 250 Celsius tin patch dropped on the top of a minus 18 degree cell straight from the freezer.

I just did some practices with old cells. The result is very interesting if I solder on the side of it I can do the most beautiful large well spread flat patches it's like magic it doesnt last longer than half a second I am absolutely convinced that it doesnt put more strain on the cell than the weld it is literelly only hot where the patch is I can touch the cell right beside the tin patch the only hotspot that burns my hand is the tin patch itself, but as soon as I wanna solder the terminals it kinda refuses the tin. Not always but many times I can only make it work 100% of the time if I sand the surface but even then it's not as good as on the side.

Anyway I go with solder at this point I think it's superior cause you can use proper copper. The problem is that the cells I ordered are pre nickeled. Which sucks btw cause I wanted to avoid spotwelds like the devil but that's what I could get for cheapo. I presume they used the shittiest "nickel". The conductivity of the steel strip is absolutely dismal. Even the pure nickel is kinda bad.

Thing is that now I see that this whole spotwelding scene is a maffia. Nickel is 17 dollars a kilo for 17 dollars you get like 200 gramms as a nickel strip sure sure it's not the raw material but how expensive is it to roll it into strips? But the "best" is the nickel plate, steel is 50 cent per kilo and they sell it at twice the nickel price. I think I'll ask for some refunds. Sure it wasnt false advertising and it was my mistake ultimately to having ordered it but it just irks me that they sell crap for a fortune. Some stripped copper wires a hot iron and steady hands that's all one needs.

if your cells are new you can try magnets and copper

https://endless-sphere.com/forums/viewtopic.php?f=14&t=106190&hilit=magnets&start=75#p1563730

Well afaic that's just insane.

Please reconsider such dangerous slopjar practices, and keep the results far away from where innocents may suffer from them.

I take it you don't live in a jurisdiction where torts law can take away all you own and more as a result of harm caused by such negligence?

Life is dangerous deal with it! If you dont like it then dont get born.

There has recently been some experimentation with the "copper / nickel sandwich" method, and the results have been very good.

Copper conducts well, with little resistance or waste heat. Also, it is relatively cheap and available. But it is very difficult to spot-weld.

Nickel and also nickel-plated steel welds quite easily at a relatively low power setting. However, nickel is expensive and has high resistance.

If you place copper sheet onto the cell end as the conductor, then place a section of nickel (or nickel-plated steel) on top, this combination welds easily, and still has high conductivity / low resistance.