Alternator?
How many amps maximum can the stereo draw? and how many amps are you actually using?
Get the first from the stereo or amplifier. It will be on the label and the instructions, etc.
To know how many amps it draws when you are playing it, you can check it with the car's ammeter.
a. After starting the car, drive around with the stero off until the ammeter shows the battery has finished charging.
b. Then turn the stereo on to the typical volume you use. Observe how far the ammeter deflects from zero toward charge.
If you hardly see it move, then its drawing just a couple amps and nothing to be concerned about.
If it shows 5 or more amps, then its worth thinking about some minor modifications to the wiring.
(The ammeter scale 40 amps to 40 amps, zero in the center. )
