I once had a new battery where there was an internal fault that caused intermittant electrical failure. It was thought that there was a fracture of the connection between the plates and one of the battery posts that would make or break over bumpy roads. Drove me nuts trying to diagnose the problem because being a new battery you assume that cannot be the culprit.

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1991 M-B 560SEL Arctic White/Grey 99,000 Miles
1987 M-B 300SDL Ivory/Palomino 229,000 Miles (sold but never forgotten)
2006 Volvo XC70 Blue/Beige
1999 Porsche Boxster Arena Red/Savanna Beige
1986 Porsche 928S Goldweiss/Brown