First off, brand new to the forum, i live in SoCal, I'm an Army Vet, and this is my first Camaro. So, here it goes, I just bought her 2 days ago, guy claimed it had a bad alternator so I bought a brand new one and a brand new battery for good measure, after which, I proceeded to drive her around for a solid 3.5 hours and no drop in voltage, this was yesterday, this morning however, I drove her to get some chow about 6 miles away and no issues on the way there, but on the way back the voltage meter on the dash said it was incredibly low, out of nowhere. So now I'm lost on what to do, she's a 1988 Chevrolet Camaro, V8, 5.0 base