So my 68 mustang 5.0 is having some battery issues. Right now I put a volt meter on it and it shows 12.25 volt, I open the door and no lights come on I go to turn the key and nothing happens. I can jump start it with a jump battery starter but when i turn it off i don't have any power. So my question is is the battery dead? it's a 10 year old battery when I do jump start it the alternator is putting 14 volts when running.