I'm just a n00b at this kinda stuff. I was wonder, if a capacitor is something that you need. I'm ready to put my sound system in my car, I just need to know if you need a capacitor or not. Thanks.
A capacitor works similar to a battery. it stores power for your amp that neither the amp or the alternator cannot supply immediately where the cap can discharge instantly depending on ESR. (ESR) if I remember right is the rate of discharge the lower the # the faster it discharges. For the most part they do what they are supposed to do but if your lights dim at night and you add a cap your lights are still dimming just not as much.. The only real way to fix this is to upgrade to a higher output alt.. adding 1 or 2 Deep cycle batteries would be better than a cap. Something like a Batcap along with another battery would help more but it comes down to the fact that the alternator is insufficient and needs to be replaced.. To answer your question no they are not necessary.
I'll be replacing my battery with a deep cycle battery. Also, the thing i'm worried about is, would I need a new alt? I have a 2003 Dodge SX. Should it have a good enough alt already?