2013 Equinox, 93k miles, original battery. After sitting over the weekend the care turned over slowly but managed to start. I decided not to push my luck and get a new battery. To save myself a return trip to the parts store for the core deposit I removed the battery from the Equinox. I noticed a bit of corrosion on the negative terminal. I had disconnected the terminal on 12/14/19 for the first time to work on the engine, at that time there was no corrosion after 7 years.
I took the battery to Autozone to have it tested. They told me the battery was at 100% capacity. They suggested I reinstall the battery and bring the Equinox in for a check. I then took it to Advance Auto to have it retested. The results were 12.8V and 483 of 485 rated CCA for a 7 year old battery.
When I reinstalled the battery I noticed if the clamp was not fully seated on the post the clamp were be loose after the clamp was tightened up. I’m thinking I did not seat the negative clamp correctly back in December and it was a bit loose. I cleaned the clamps and the battery posts before reinstalling the battery. It started right up and the alternator voltage was 14.5 - 14.8V at the battery terminals with the headlights on (it was dark at this point).
I live in South Jersey near Atlantic City.
Is it possible for a 7 year battery to be in such good condition? Could a loose battery clamp cause the corrosion and the difficulty starting?