If you go this route, use a 1959-1981 one cent coin. It's a 95% copper 5% zinc ALLOY. The 1983 and up coins are 99.2% zinc with just a thin .08% layer of copper coating on it. They made both types in 1982, so, unless you know the difference, avoid that year. Personally, I'd get some lead shims that are made for battery posts. Not sure they are still available, but, they used to be. Either that, or shave the battery cable connector as already mentioned. You sure you have the correct cable on the correct post?