Hi, My car battery had died in the morning but was fine y'day night. My mechanic put a meter on the battery terminals and it showed a reading of 13.72. He says the reading shows the alternator is weak as the ideal reading should have been 14.2. He wanted me to change the alternator. Would it be right to change the alternator or the battery on this reading. Also the car has been running fine all day today but I am worried that it may not start in the morning tomorrow as both my mechanic and the RACV guy said the same. Thanks.