Altnator not chargeing bit checked ok.

You can't strain an alternator. They're like a water pump; they won't pump more water than their capacity allows. Alternators won't pump more current than their capacity allows. The whole story changes a lot if you got suckered into buying an '87 or newer GM product. Their AC generators, ("alternator" is a term copyrighted by Chrysler, but that's irrelevant), have all kinds of design problems built in and running them near maximum pretty much guarantees repeat failures.

Even the most heard-of-hearing kids with the loudest amps don't need more than 90 amps from the alternator because those units don't draw maximum current all the time. They draw the most during the bass notes which makes the car sound like a dump truck rolling down the highway. In between the low notes, current is very low and the battery will regain any charge it gave up momentarily. At issue is getting that current to the amp when it's needed. If you truly understand electrical theory, you will be familiar with "voltage drops" in a circuit. That is a result of the resistance in the wires and the amount of current you're trying to run through them. Giant capacitors are a gimmick to overcome the effects of that resistance. If the manufacture adds a silly digital voltmeter to it, you can watch the readings change while sitting in the trunk.

A capacitor does the same thing as the car battery only it is much smaller electrically. A capacitor the size of the trunk would power an amp for about 20 seconds and would cost about 20 times more than a car battery.

I'm not sure why everyone today needs to be entertained every waking hour but many of us do not appreciate the noise youngsters pump out of their cars. I'm not so insecure as to require that much attention from strangers, and I'd be embarrassed to get negative attention that way.

You can reach a lot more people with a PA system if that's your goal but music is supposed to be pleasing to the ear, and I haven't heard much of that in years. Imagine if you were forced to listen to an opera singer against your will. No one is going to convince you to like it by forcing it on you. Thank goodness as people mature they lose their desire to beg for someone to notice them.