Can nickel plate strips be soldered onto 18650 batteries using a regular soldering iron or are they only for special soldering devices?

 

I have soldered nickel strips many times with ordinary solder. I use leaded solder and flux.

As for 18650 batteries, there are so many poor ones on the market it is impossible to know whether it is the battery or technique when there is failure.

 

Are solderable with normal 40/60 -60/40 lead tin but using the flux of 1) conc ZnCl2 made of powder 50/50 in water or 2) conc H3PO4 (50-80%) 3) Aspirinum purum (but not those with microcellulosae). May be used like colophonia or alternatively dissoluted in ethanol. All three must avoid the inhalate the vapor and all three must be washed after soldering.