Standard jumper cables #4awg, so good for 70-90amps. Barbed wire probaly #14 awg, good for 15-20 amps if copper. Steel is about 7-10 times more resistive than copper, so maybe good for 3-5 amps? Just a guess. Two strands, so maybe good for 10 amps.
Wire is going to get red pretty quick. Its going to be hot when you disconnect.
I suppose Ive seen worse ideas.