Preparing 18650 battery ends for spot welding

[byteharmony]

What are the best ways to clean up recycled 18650 cells to prepare them for spot welding?

I have a grinder - little harsh maybe?
Dremel tool - like this idea
Manual file - will this take too long and be putzy?

Thx in advance! Looking forward to using my spot welder!!

 

[Bobbychas]

A Dremel with a small grinding bit is perfect

 

[Substrate]

Definitely danger-zone category time.

Do you really want to be scraping/filing/dremeling little slivers of metal under the end-cap, where the negative case is very close to the positive cap?

C'mon now.

 

[A.Justice]

I have used a small piece of 800 grit sandpaper with decent results. Clean it with 91% isopropyl alcohol first, then just a few swipes of the paper, those cases are REALLY thin.

 

[Maintenance guy]

I know this thread is old but contrary to your belief a Dremel works just fine. I buy new battery packs from Batteryhookup and disassemble them all the time with never one single issue. I lightly use the small thin grinding wheel which if there was any such metal bits it is thrown clear.
Here is some 18650 cells I broke down and very slightly ground down as little as possible. These specific cells were 3000mah at 100 % for like a dollar a piece and can handle 10 amp discharge. I use them all the time for many things. Really simple task that doesn't take rocket science to figure out , saying this is dangerous is just plain ignorance. I use these also to repair power tool batteries and not one mishap yet with very satisfied customers. Ends are blown off with air then rings attached then it is assembled and tested.?

Regards,
MM

 

[mschaus]

The people on the (rude) Facebook forums will scream that dremel/sanding will allow the metal to corrode. No one there has ever shown any proof of that though. Anyone here have actual insights or data?

 

[A.Justice]

The people on the (rude) Facebook forums will scream that dremel/sanding will allow the metal to corrode. No one there has ever shown any proof of that though. Anyone here have actual insights or data?

I don't know about the metal corroding, but I do know that I've sanded those to the point that fluid starts to leak and bubble out under load at the solder joints. It didn't take much at all, if I had to put a number on it I would say it was 6 to 10 swipes with a 200 grit paper. It didn't happen immediately either, I came out the next day and could see little bits of fluid coming out from around the solder, and when I started to charge the pack, the fluid started bubbling angrily.

I think it all depends on the specific cell thickness, and how steady your hand is with a rotary tool. I'm sure it's possible for some guys to just nick the little bits of nickel strip off perfectly every time, but my hand just isn't that precise.