I was idling in a parking lot and my battery gauge went down a lil then i pulled out into a street and battery light came on and the voltages went way down but not completely. Would it be my battery or my alt?
Yep. Or remove each and have them load/bench tested in the store.
A voltmeter could be handy - check battery voltage and output voltage at the alt. Inspect the fusible links on the alt charge cable - about 6" from where the cable attaches to the distribution block. make sure the links did not burn.