Chinese bad-dery clamp

Yeah that's pretty funny. Not that it had anything to do with the break, but you used the wrong size terminal for that post. There is a positive size (large) and a negative size (small). See how the terminal is touching at the bolt holes? You can't tighten it any further. They are not supposed to touch, because then the terminal is stretched and no good. It will not tighten up anymore. When you replace it, get the smaller size and it will work better.