Spot weld residuals

Travis Watson

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Joined
Aug 6, 2017
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The cells I'm breaking apart are currently spot welded. I can pull the majority off easily enough, but there are small remnants too small for pliers to grab.

Any advice on removing these bits? Dremel? Chisel?


Here's a pic to be clear what I'm talking about.

image_htptmw.jpg
 
I just flatten mine on the bench and don;t worry about it
 
Thanks for replies. Does it make a difference if you're going to spot weld the end vs. solder?
 
TravisWatson said:
Thanks for replies. Does it make a difference if you're going to spot weld the end vs. solder?

Soldering doesn't matter, I just solder right over them. I would think you need as clean a surface as possible for spot welding, not sure since I have never tried it personally. If you're concerned, you can very carefully tap the end of the cell against a bench grinder to remove the nub that's left.
 
Spotwelding you need to have it a bit cleaner otherwise you might get issues getting proper contact.
 
daromer said:
Spotwelding you need to have it a bit cleaner otherwise you might get issues getting proper contact.

Hey gang.
On the same lines, what about damage to the cells when removing the tin/nickel strip with force?
I'm fairly careful (using small nips) to curl off the metal strip from the batteries, but in a lot of cases, they just get "ripped off", leaving some spot weld pieces. I nip them and make as smooth as possible, but.... I've seen that some people "press" the remains back down with pliers, wooden mallets, and even tap them with hammers on the workbench to make smooth and flat.

Sure, A good reason for as smooth and flat as possible is to ensure a good connection to the chargers/dischargers, etc.

Thinking about it, as for re-soldering, and keeping things flat, why not just leave the tin/nickel piece on the anode and cathode and carefully snip them with sharp cutters.
This way, we don't rip the spot welds or the metal strip off the battery, potentially bending the ends and leaving spot weld pieces.

Question to the group - is it "easier" to solder onto the tin/nickle strip? I have found no difference. However, by leaving the metal piece and the spot weld there, does it cause any residual heat inside the battery when soldering to the remaining metal strip, as compared to soldering directly to the bare battery ends?

What about the holes left when pulling the spot-welded strip off the batteries? What about the CID's? Do they get damaged when we "tap" on them, or pull the metal from them?

I'm just looking for some safety rules of thumb and other's experiences.

Thanks :)
 
The Nickel strips are softer than the shell of the cell. So, ripping the strip off generally will do no harm to the cell. However, there are few times when the weld is so darn good that it does rip a hole. Rolling the strip to remove it is a good practice to have as it makes the strip tear if the weld is too good.

I don't believe there is an added benefit nor a negative impact by leaving a little strip behind. If you solder onto the cell, there isn't going to be more or less heat applied to the area, unless you have quite a bit of strip there.

It's a good idea to tap the shards left by the removal process down a bit so as to not impeded the connection with the chargers. I usually just use the same pliers I'm pulling with to gently tap them flat again.

It is also a good idea to just remove the tabs all together. Reason being that all welds are not equal. Some welds are just piss poor and will create a lot of heat at those spots. Unless you have a pack that generally is hard to pull the strips off to begin with, then I'd remove them.

There are different methods of removal. Rolling with pliers is by far not the only option. You could snip the strip as close as possible with flush snips, then use a small flat head screwdriver (or something similarly small) to go under the strip to raise it up, then flush snip from underneath. The idea really is to not pull straight away from the cell as this greatly increases the chance of ripping a hole in the cell.
 
If there are holes, then yes. You can tell if there is a hole if you smell the electrolyte. You'll know it when you smell it. Very distinct smell
 
If holes then toss the cell. You destroyed the integrity of the cell and if there is a CID that wont function hence no protection anymore.

On laptop cells that is rare but on cells for high current applications the nickel strip tend to be thicker and harder to remove. On those it will happen easier. Just be carefull and if you going to spotweld or solder you can leave them.
 
i used a dremel to carefully remove all of mine. ends of my cells are all completely smooth now :)
 
Wattsup said:
These are the best tool I've used for that job. Not this particular brand but same thing.
Leaves a flat clean surface.

Wear glasses as little pieces of nickel can shoot off

https://www.aliexpress.com/item/New..._expid=3449b3f8-41f9-414e-b280-10e818cd457f-2

Ya, Thanks for the link. I use almost exactly the same kind of tool and have very good luck with it. The question really was .... if I leave the nickel strip on the cell (not rip it off, but trim around it), are there implications to the soldering on top of it. I do find that when I pull then nickel strips off, even when very careful, quite frequently the cell metal gets a little bent (stretched, or whatever). This happens with gentle rolling of the nickel strips with this kind of tool. I haven't left holes as far as I know, but if I did, they would be so small it would be hard to notice. In most cases, what remains is pointy/sharp metal which sticks up where the welds were (sharp enough to put holes in my finger). I snip those, and don't bang on the cell (as others say they do). I personally think tapping on the cell ends (especially the side with the CID in it) is not a good thing. I am trying to completely minimize any malformation of the cells themselves or cause hidden damage internally. I'm looking for other's opinions as well.


Sonic01 said:
i used a dremel to carefully remove all of mine. ends of my cells are all completely smooth now :)

dremel is a cool tool, but with thousands of cells, this can get kind of tedious. It is a good idea, however.
 
Tapping lightly on the cell won't do any damage to it. You gotta remember the nickel strip is fairly soft metal compared to the shell of the cell. So just gentling tapping will flattin the nickel out but it won't do any damage to the cell. If you do do damage to the cell, you smacked it waaaaaay to hard.
 
howiegrapek said:
why not just leave the tin/nickel piece on the anode and cathode and carefully snip them with sharp cutters. This way, we don't rip the spot welds or the metal strip off the battery, potentially bending the ends and leaving spot weld pieces.

I try to leave as much tab on the cells as possible. I think it is far preferable to solder to the strip than directly to the cell. Some cells really, really don't like to be soldered to. I swear, I think one started to 'take off' thermally after I had the iron on it too long. (I de-tab weaker ones and put a button of solder on (+) and dremel the burrs off (-) after testing: they make fairly decent flashlight batteries...)
 
Flush cut snips are my favourite tool for taking apart battery packs. You can nip off any remaining bits with them. I've also found that if I lift the nickel strip and get the tips around the spot weld and gently twist the cell while snipping, there is almost nothing left behind. I found before that when I just pulled off the tabs, I would sometimes bulge the negative terminal, and really bent a few positive terminals due to very strong spot welds. This doesn't happen any more.

I also have a larger ball peen hammer (the one's with a round ball on one end) that I 'scrub' the terminals against (no tapping, just rub the battery fairly hard), and this works great to flatten any pointy bits.
 
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