soldering nickel turns out to be simple

[whatever]

I've always had problems soldering nickel coatings, watched a video on youtube showing a commercial acid being used, thought I
would try some rust converter I had lying around ( happens to be phosphoric acid), and bingo, just a little of it and the solder sticks
extremely well. Also makes soldering older wires that solder wont stick to easy. A small discovery I wish I had found out many years ago. Since rust converter is easily available and you can buy a litre for small price its ideal for the job.
I was soldering onto nickel tabs, but should work on 18650 cells also.

 

[ZeroEm]

That's great, having a clean raw surface with no coatings works for most things soldering, welding and painting. Raw surfaces react to the oxygen badly that is why everything is coated and is a pain to remove but prepping makes a professional job.

 

[Hillhater]

Acid based flux’s are common in industry and are very effective,,but.
As with all acid based solder flux’s, be sure to clean and remove ALL traces of flux residue after soldering otherwise severe corrosion and connection failure will occurr in time.
Also be aware that as you solder ,acid fumes and vapour will transfer to nearby surfaces.