My experience as well, more copper surface needs higher voltage/ longer time.
I've tried to do several at a time and failed.... Glorious.
For me a LiFePO4 cell worked perfectly, as the higher capacity improved the quality and speed.
After plating 100 Bus-bars or so, the voltage hasn't dropped at all...
I didn't not do capacity test before and after, bit it didn't use a lot of power
Tin / nickel / zinc, all work about the same, where Nickel is the most lovely.
Tin makes it more easy to solder a wire if needed, but will get dark gray over time.
(Nickel stays lovely)
Zinc... I tried from old batteries..
That did work, but looks terrible.
For resistance, they are all about the same.
(I have micro ohm meter)
Funny to see how a car key, tip to base, will have higher resistance then a LiFePO4 cell, with correct mounted Bus-bars
Apparently chromium doesn't work well with electricity ?
I plated over the Zinc ones with Nickel, just to see if it works.
No problems!!
And strong bond.
Like the copper, the older layer needs to be clean, no fingerstains or other issues.
I didn't notice difference in resistance.
My copper bus-bars are about 115mm long, 17mm wide and 0.6mm thick
Loads of mass...
@Micky , I did not see your cells without nut and bus-bar.
Some of the new sellers laserweld studs inside the aluminium terminals.
If they do, the studs are usually galvanised iron.
(Check with small magnet)
Seldom aluminium!
And, according to local laser welding company, can not be stainless steel studs, as you can not weld aluminium and stainless steel together.
I know this is for TIG, not sure it that still holds up for laser, and if a pre-treatment would make it possible.
Probably for LiFePO4 cells, they don't go that far in developing for end users
Most just drill a hole, tap, and that's it.
Some drill, tap and laserweld.
CalB cells have incert for studs and is build for this type of mounting.
Even have a nut on the edge of the terminal to be able to tighten, without stressing the housing of the terminal. ?
Anyways...
If you have stainless grubscrew, and you use them in the aluminium terminals, do use Loctite red and primer.
For the nuts.. if you are afraid they will vibrate loose..
Spring washer or Loctite blue.
You probably don't want those to be absolutely permanent....
You might need to replace one of the parallel cells if it goes bad.
Nuts and Loctite red (+primer)..
You need grinder or apply 250-300c heat. Last one will kill the joining parallel cells as well