4boyssss

iTrader: (8)

Here's one of my favourite definition of a capacitor:
An electronic device that can store electrical charge. The charge stored Q in Coulombs is related to the capacitance C in Farads and the voltage V across the capacitor in Volts by Q = CV. The basis of a {dynamic RAM} cell is a capacitor. They are also used for power-supply smoothing (or "decoupling"). This is especially important in digital circuits where a digital device switching between states causes a sudden demand for current. Without sufficient local power supply decoupling, this current "spike" cannot be supplied directly from the power supply due to the inductance of the connectors and so will cause a sharp drop in the power supply voltage near the switching device. This can cause other devices to malfunction resulting in hard to trace {glitch}es. (1995-04-12)
Caps may not 100% stop your lights from dimming but sure is healthier for your amps (specially mosfet type amplifiers) as well. So many people just think about supplying a number of currents such as by going big on alternator but not realizing that you're also increasing the so called "spikes" which could affect the components in the amplifier. We, in S & S ELECTRONICS have seen so many blown amps caused by just boosting your car with a bigger rated vehicle while its system are still connected - this is one sample of how a "spike" can cause amplifiers. With a capacitor - it should protect it as it also serves as a filter...

We could probably write so much pages on this argument but to be short, "big 3",upgrading alternator, using bigger size wires,or adding an extra battery, are all good to have but would be better to have a rated capacitor in addition.

johnw

iTrader: (4)

A cap will only MASK your problem not fix it, upgrade Alt, Batt, and Wire and you wont have a problem, if more power is need still add more batteries. Period. This is BASIC OHMS LAW. You need POWER to make POWER. A cap is only good for about 1 sec then it becomes a resistance to the rest of the system as it pulls power away from your amps to recharge.

Micardio

Caps are good when used for the right reasons.
A cap should not be used as a replacement for good wiring, battery, or sufficient alternator.
A cap is meant to filter voltage spikes and supply reserve current for very short intervals.
If your system can draws more power the alternator can supply a cap wont stop your lights from dimming, but if your alternator can produce the power needed then the cap will do what its supposed to.

The reason why upgrading the alternator alone will not stop lights from flickering is when a load is first applied to the system the alternator has to wait for the voltage to drop. THEN the internal regulator supplies more current to the field coils returning the system voltage to normal. This happens quickly but you will still notice it.
The battery Works as a capacitor by evening out these voltage fluctuations.
Batteries have much more capacity than a caps do. The only problem is the average car battery does not have substantial capacity above 12.6V. Anything above this is surface charge and this is where a capacitor can supply the added current when needed.
From what I've seen at competitions, some batteries can hold a lot more surface charge and minimize the need for a capacitor.