so when i have my subs on for about 20 or 30 minutes and i turn my car off it hardly has enough juice to get started. I was wondering how to check the voltage (where), becaus i know it is not supposed to go lower than 12 volts. also i have a 700 watt max 350 rms amp by alpine mrp350 and a 1994 jeep grand cherokee. thanks
use a DMM on the battery. check when the system is on and playing at high volume. if the voltage drops below 12V then you will end up damaging the battery, alternator, and/or audio components. if the battery sits below 12V when the car is off and has sat for a while, the battery is damaged and needs to be replaced.