Yep, 12 gauge is way too small. Sounds like my first set of jumper cables.
I was in high school, and was out for summer. I was working at the plant, and my best friend was working at the local S&H Greenstamp store.
Sometimes you got decent stuff for all those books. He spotted a "heavy duty" jumper cable set.
Since he worked there, he could buy stuff without using stamps. The price was decent, and they were huge cables.
The clamps were a little flimsy, but the cable part was way thicker than the ones we used for jumping off the 390s in the route trucks.
So, I grabbed them and through them in the back of my CJ.
Couple of weeks later, saw a girl I went to school with sitting in a parking lot with the hood up.
She said she had gone in the movie and left her lights on. Her brother was coming with jumper cables.
Not a problem, I carry jumper cables at all times, don't you know. Pulled along side, she tried it as I was getting ready, but it would only grunt. Hooked up my nice new cables, told her to hit it.
I think it was weaker.
Wiggled the connections, tried it again. Nothing.
Told her she probably had trouble with her starter, offered to give her a ride home. About that time, her brother showed up with a thin set of flimsy jumpers. I took mine off, he hooked his up to my Jeep,since it was right there, and her car spun over like the battery was never dead.
It was so embarrassing. Next morning, I went to NAPA and bought a set of the heaviest jumper clamps they sold.
Started taking the clamps off my cables. Figured it had to be the clamps, since the wire was so big. I would just put on new clamps and have great cables.
The stupid cables were 4 conductor 16 gauge wire with each conductor separately insulated with thick insulation!
They were so thick, because of all the insulation. I don't think they added up to 10 gauge wire.
I threw the whole mess away, went back to NAPA and swapped the new clamps in on a set of 2 gauge jumpers bonded together 25 feet long.
Great cables until the clamps failed. I examined them, and discovered the problem. The cable only hooked up to one side of the clamp. If that side did not make good contact, all the current went in the other side, and through the steel rivet and spring to the cable.
This either melted the rivet out, or got the spring red hot and caused it to lose its temper and the clamp would not close.
I bought the same set of clamps I had traded in again, and hooked a small 4 gauge jumper from one side of each clamp to the other and then put them on the cable.
I had those jumpers for almost 15 years before someone stole them. Never had a truck they would not jump off, and never had a clamp fail.
