I have seen the problem with the clamps and posts on a car that my wife had a while back. Visually inspected those, but not to say that is not the problem. Have not experienced that particular battery problem yet. Most of my professional experience is with natural gas compressor units, that are started and powered by a 12V system. I have seen a 12V system do a lot of strange things in those years. Will definitely check both suggestions when I am able. The way it lost all system voltage, I just instantly figured that I had tried to pull too many amps through the system, and fried a component after the battery. Thank you very much!! I hate not being able to get my hands dirty, been doing it my life!
