I just purchased a brand new battery. After 6 days of use, it is dead. I checked my battery and alternator by an expert, he says they are both fine. However, this problem has persisted for two weeks now. The car works fine for 6 days but then loses power on the seventh day. When this happens I have to go charge it by a car dealership or have a friend give me a jumpstart with they jumper cables. Could it be an electrical (wiring) problem?