Hi this week end went to fla to fish my father inlaw boat the batt was dead to i jump him off then went fishing later that day .i had to jump him off agin this time i left my boat running with the jumper cables on with my motor running and tried to jump him of it woudn't so i left my out boad running and took out my batt and used it to jump him off and put my batt back in . The next morning went to go fishing batt was dead came home and charged motor fired right off . Now the problem with the key off as soon as i hook up the batt the gauges jump the the volt gauge gos to 13.5 volts with the key off why . It did not do this till i turn the key on . Help