66 Chrysler 300 – Lights Dimming

So I've noticed my dashboard lights finally working but sometimes its bright but it keeps dimming down. I don't drive the car at night as i found that sometimes when I come to a stop my car dies out. Front headlights are also bright but most of the time dimming down and back to bright then back down low. Any ideas where to look? I thought it could be the battery
Author: Umeracle