Solution: Extract Cells from Sealed e-bike Batteries

cadric

Member
Joined
May 3, 2018
Messages
110
Hi Gents,

finally I think I can give something back to the community and all you great Guys, that helped me on my way to build my own Powerwall.

For around a year I collected cells now, a lot of them in sealed e-bike Packs, which were a pain when it came to extract the single cells but had most of the time only the BMS broken and the cells still very usable.

Some of you tried to help me with tipps and I found out that I was not the only one here struggeling with theses packs.

image_qutslq.jpg


Then I tried to use them as a pack as they were and just extended them to 48 Volt, which I think was the second best solutioin.


But now I think I have the best solution:

I used a Pack, where I already stripped of the bus bars and a lot of the black sealing for the first test.

image_kpesos.jpg


I bought a so called Forstner Bohrer ( didn't find an english description ), normally used to dril joint holes in furniture doors, with 18mm Diameter, cut out the inner centering drill


image_nbcvhu.jpg


and drilled on the negativ side of each Cell.


image_wofkdw.jpg


Then I used a plastic pipe with a dowel in the corresponding diameter for the positive pole


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and carefully used a hammer to drag the cells out of their cage from the pos side.
Mostly the shrink got lost, but that is ok.
Importand ist, neither the negative nor the positiv pole get hurt this way.


image_xxvnkz.jpg



so now I got a lot of mostly perfect cells:


image_hfibqi.jpg




That is my way to go now.
I hope this is also off use for some of you.


P.S. What I forgot to mention: Use a stand drill for being as accurate as possible.

Reagrds

cadric
 
Forstner Bohrer = Forstner Bit ;)
Interesting, if I do a search with your words, all results were in German. Which is odd, considering google usually gives me the English versions

When drilling out the plastic, the bit (bohrer) didn't damage the cells at all? Are the light scratches from the bit? If so, are going to want to put solder across the whole end to seal up those scratches. Otherwise you're taking a risk of corrosion occurring. Once you break through the silver outside layer, there's steel underneath.
 
Hi Korishan,

yes, the scratches are on the pure metal case of the cell. I'm going to solder the cells anyway when I build the packs.
I have several blocks where I already took of the busbar and soldered the cells. Even on these the drill method works.
But I also still have a lot of packs with original bus bars and these will help to avoid scratchings at the cells.
I just have to leave them until I'm ready with the drilling.

cadric
 
You could also try www.18650shrink.com

These are provided by our very own 18650Shrink. I'm not sure if he does overseas shipments, though. I would contact him and find out first. Depending on your order size, he may do it.
 
Korishan said:
Forstner Bohrer = Forstner Bit ;)
Interesting, if I do a search with your words, all results were in German. Which is odd, considering google usually gives me the English versions

When drilling out the plastic, the bit (bohrer) didn't damage the cells at all? Are the light scratches from the bit? If so, are going to want to put solder across the whole end to seal up those scratches. Otherwise you're taking a risk of corrosion occurring. Once you break through the silver outside layer, there's steel underneath.

I would be looking for a way to replace thenickel plating the cell. It couldn't be that expensive, given scrap bus bar from pulling apart packs.
 
Ahhh, nickel plating requires putting the cell in a nickel sulfate solution and using electrolysis to replate the cells. I'm not sure how well that would work with these cells. Normally this is done before the innards are installed at the manufacturer.

I'm not aware of any good nickel plating using a different method. Maybe someone else has.
 
Korishan said:
Ahhh, nickel plating requires putting the cell in a nickel sulfate solution and using electrolysis to replate the cells. I'm not sure how well that would work with these cells. Normally this is done before the innards are installed at the manufacturer.

I'm not aware of any good nickel plating using a different method. Maybe someone else has.

Its only the -ve end that needs to be plated. So only the base would need be submerged. By clamping the cell by its side, the chemistry inside the cell would go completely unchanged, as it would not be part of the circuit.
 
Geek said:
Its only the -ve end that needs to be plated. So only the base would need be submerged. By clamping the cell by its side, the chemistry inside the cell would go completely unchanged, as it would not be part of the circuit.

I understand that. I'm thinking more of safely and securely holding the cell at the proper position/depth without the risk of the cell falling into the solution. With it being nickel sulfate, the solution is "very" electrically conductive and a cell falling into the solution could be a very bad thing.
 
Korishan said:
Geek said:
Its only the -ve end that needs to be plated. So only the base would need be submerged. By clamping the cell by its side, the chemistry inside the cell would go completely unchanged, as it would not be part of the circuit.

I understand that. I'm thinking more of safely and securely holding the cell at the proper position/depth without the risk of the cell falling into the solution. With it being nickel sulfate, the solution is "very" electrically conductive and a cell falling into the solution could be a very bad thing.

I was thinking of a jig made ofmetal rings, suspended over the solution, so it would be impossible for a cell to fall over, or be dropped into the solution. Keeping the cells propped up, off the bottom with some kind of plastic mesh.It would be a task to construct, but once complete, it would be easier than soldering the whole base. Not to mention the shiny clean (and slightly rough) nickel surface left for future soldering.
 
ajw22 said:
You can get cheap precut replacement "18650 sleeve"s and insulation rings on aliexpress. Looks much neater and will probably save you from stupid accidental shorts.
The cheap 300w heatguns work best.

Yes, I already have about 1500 new sleeves waiting to be applied, and the spacer rings are mostly not destroid and still useable.
But first the cells have to show their power.
 
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