Little holes

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bghenj

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May 1, 2018
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Hi everyone, great forum. Got a batch of batteries which are a bit difficult to remove, the bus bar is spot welded on very tightly. Resulting in some cells having little holes, see picture. Any tips on preventing this issue?


image_ghpubj.jpg


Anything to worry about? I've stored them outside the house for the moment. Thanks!
 
Hi mate,
definitely a problem. They are no longer sealed now. Once you would use them the electrolyte paste becomes more fluid (as temperature increases in the cell) and it will result in it leaking out. Not a good thing. Without the electrolyte the cell cant function.
Im afraid you need to throw them away.

only way to prevent it is to not remove it. I have hundreds of cells like that. With all I just bent up the plates, snipped them off about 3mm before the spot weld and then bent it back down. thats the best way.
 
Holes in the cells, big problemo! Do NOT use those cells for ANYTHING. Well, except for maybe dissecting.

One way to keep from doing that is to roll the pliers while holding the strip. It won't cause as much damage. If you pull parallel to the cell in the opposite directions, that is the possible outcome. Rolling perpendicular to the cell greatly reduces the stress on the cell. I did 100's of cells that way and I don't remember ever having a hole in one afterwards.
 
Couldnt it be soldered as we do when soldering fuse wire on it? I know not the prefered way but it t does seal...
 
It won't seal. The cells are under pressure during operation. Solder would just blow off and could cause other issues. Plus, you don't know how the electrolyte will effect the solder. In most cases, it's bad enough to make SMD components fall off of a PCB.
You could take JB weld and use it to patch a hole in a crack in the motor block, too. But does that make it safe to operate normally? I wouldn't trust it but to limp me back home so I can replace the motor.
 
As per The_J-Man : If you have a strip spot welded on just cut each side and leave the strip in place. The reason is that this should help with soldering and also prevent the cell from being heated up as much when you solder connections to the cell.
 
I just came across this for the first time today as well. I had a few cells with a haze across them and some small bubbles on the negative end. I brushed one of the bubbles with my pliers and it turned into a hole.Even though all the cells were at a high voltage I tossed them all in the recycling pile.
 
Great information, thank you all - much appreciated. They are going to the battery disposal bin!
 
Charly144 said:
Couldnt it be soldered as we do when soldering fuse wire on it? I know not the prefered way but it t does seal...
Click to expand...

This is an interesting idea. I have a cell that's got a hole from short-circuiting it a while back that's staying o a concrete block for the moment. I may give this a try and stress it to limits and see what will happen. Although the limits are a bit high, 22A max current on this one...
 
Just anouther idea to consider if you do not want to keep the tabs

You can knock out the spot welds with a dremmel and small grinding wheel. If you are careful it is not difficult and you leave 99% of base metal intact.
 
Mate, usually we have to deal with several hundreds/thousands of cells.... ;-)
 
If there is a hole in them then bin them. They have already been contaminated from air so even though you make them sealed I would NEVER keep them. There is no way i would do it.

If you know that a set of cells have this issue leave the tabs on instead!!
 
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