I started the truck an at the battery use a ampmeter an check voltage, then turn on headlights an air with blower on high check again, then turn on the steroe loud so youre pulling power check again.
If you have 12 volt's youre ok.
The alt voltage can be high an you can still kill batteries. I only run optima with a aftermarket stereo, you can discharge those without slowly killing the battery.
Better to die on you're feet than to live on you're knee's