I have used #2 welding cable on three cars ( have it on my 505" barracuda right now) when moving the battery to the trunk, and used welding cable on 4 diff. cars. I have never ran a full length ground cable on any of them, and never had a problem w/ any of them. II f # 2 is getting hot, something else is wrong. I do however have have a motor plate and extra grounds located in various places thru out the car. My motor plates have always grounded the engine successfully. ?????????? who kjnows ?