Flux

[DouglasXK]

I looked under one of my battery packs and where I’d soldered the BMS wires to the nickel strip welded to the batteries, there is brown-ish crud around the solder joint. Looking this up I discovered that the flux I use (standard ScrewFix stuff) might not be the best! Indeed, add a little water to this toxic flux and it might be as bad as pouring sulphuric acid on the nickel. The nickel is 100% or a midge’s dick near to it. However, I do get beautifully clean and sort of professional solder joints with this stuff and I’m not a good solderer.

Can somebody please recommend a good, non corrosive, good to use, solder?

 

[Deleted member 4366]

I don't think anybody else worried about that. I just use 60/40 tin/lead cored solder with whatever flux there is in it. I've never seen any corrosion inside batteries except a couple that went for a swim in the sea and another that had half-filled with water. In all those, it wouldn't have mattered if the joints had been brazed with gold. I've also seen brown gunge from leaking cells, but again, the battery dies due to the bad cells, not the subsequent corrosion.

 

[DouglasXK]

The pack got damp one day

 

[DouglasXK]

I don't think anybody else worried about that. I just use 60/40 tin/lead cored solder with whatever flux there is in it. I've never seen any corrosion inside batteries except a couple that went for a swim in the sea and another that had half-filled with water. In all those, it wouldn't have mattered if the joints had been brazed with gold. I've also seen brown gunge from leaking cells, but again, the battery dies due to the bad cells, not the subsequent corrosion.

I experimented using actual nickel and found soldering it quite satisfactory without flux, thanks for that. An xt90 connector which was always difficult to solder also was relatively easy. So, thanks again.