I bought a 2003 Nissan Maxima thinking it would be a good purchase however driving off from paying the seller it turned off on me before it turned off. It started making noises near the radiator. It only stays on if I have a battery pack connected if I disconnect the battery pack I can only drive for maybe half a mile. I checked voltage and everything and it seems to be overcharging slightly. I have above average knowledge of how to fix cars. I do have a jack and some tools. Can anybody tell me is this fixable and how should I fix it?