Hello people. I have a 2013 hammerhead gts. The problem is that when I go and drive for a while and stop to get out then back in it immediately will turn over partially and then not start as though it doesn't have any charge. But when I put a meter to the battery it has 12.51 volts. But if I charge the battery it starts fine. Does anyone know how to help me? It seems as though it is not charging.