I stumbled over this:-
It appears to be somewhat similar (IMHO) to a battery welder a friend onf mine made some years ago, and his is still working!
regards
Andy
Dark Welder 2: My DIY battery tab spot welder
After the failure of my $16 battery tab spot welder, I saw Kevin Dark’s DIY version. But it wasn’t exactly what I needed, so I decided to build a modified version. The Modified Dark Wel…
scottiestech.info
regards
Andy