Removing welded tabs

[yopappamon]

Am I asking for trouble by removing welded tabs from my NiMh f cells? Will they come off or will it rip the cell end up?

I want to rearrange the pack I have and need to move two cells. They have 4or5 spots welds each. Or should I just cut the tabs and solder a wire on?

 

[neptronix]

i vote for cut the tabs.

In my experience, desoldering something involves putting a lot of heat on the component compared to soldering it. I've ruined things that way :|

 

[cell_man]

If you haven't got a spot welder to make a new weld it's better to cut the existing tabs and solder onto it when you re arrange IMO.

 

[texaspyro]

If you are going to remove a tab, the best way is to grab the loose end with a pair of needle nose pilers and roll the tab around the pliers like you are opening a sardine can. The tab should come off without damaging the cell. If the weld was any good, it will leave behind little bits of tab on the cell that you should grind off with a Dremel tool.

 

[yopappamon]

Thanks for the help. I did the cut and solder. Looks like the better choice as I have no way to reweld.

 

[mwkeefer]

If you are going to remove a tab, the best way is to grab the loose end with a pair of needle nose pilers and roll the tab around the pliers like you are opening a sardine can. The tab should come off without damaging the cell. If the weld was any good, it will leave behind little bits of tab on the cell that you should grind off with a Dremel tool.

The issue or potential issue here is if the needle nose cause a short between the body of the cell and the positive end which the tab is spot welded to.

-Mike

 

[cell_man]

Thanks for the help. I did the cut and solder. Looks like the better choice as I have no way to reweld.

That's the best way IMO. Less chance of putting too much heat into the cells than if you solder directly onto the cell. Soldering directly onto the case is no problem also, you just need to use the right tools and technique.

 

[texaspyro]

The issue or potential issue here is if the needle nose cause a short between the body of the cell and the positive end which the tab is spot welded to.

Nawwwh, now that wouldn't happen, would it? Yeah, pull up the end if the tab, grab it with the pliers, keep them level and away from the can, roll the tab off with some upper pressure on the pliers, downward on the cell, so the pliers are trying to move away from the cell.

(and on A123 cells the button end of the cell is negative!!! a lot of people have made magic smoke out of that one little difference).