A: The rule of thumb is to put in 1 Farad of capacitance for every 1,000 watts RMS of total system power. But there is no electronic penalty for using larger value caps, and in fact, many see benefits with 2 or 3 Farads per 1,000 watts RMS. The larger the cap, the more charge is available for the amp when it needs it.
Do you have to have a capacitor for subs?
Capacitors make it easier on your alt + batt but are generally a waste of money, plus it takes power to charge it so the sub isnt seeing at much power as it could be. But a good rule of thump for capacitors is 1 Farad for ever 1000W RMS. so a 1 farad cap would be optimal for your setup.
When a battery is connected to a capacitor Why do the two plates?
You attach a battery, which at first adds a single electron to one side of the capacitor. The electron has an electric field that repels other electrons, and this field reaches through space and pushes on the electrons in the other plate, causing that plate to acquire an induced positive charge.
How much energy does a capacitor store?
The rechargeable C cell I mentioned above (1.2v, 2.2Ah) holds 9,500 joules. A capacitor holding this much energy at 1.2v would have to be (2 x 9,500 / 1.2 x 1.2) = 13,000 Farads, so if it helps, you can think of a battery as an enormous capacitor.