Sounds like battery and or charging system connections problem...Clean battery terminals and charge the battery complete...How old is battery...If it is over 3-4 years old have it load tested when fully charged...I have seen a fully charged battery drop like a stone on a load tester..........

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83 300CDTurbo 307,000
2005 Honda Element 266,000
56 Nash Ambassador Country Club Special 34,000(under restoration presently)

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