Caps and batteries are a band aid fix for a bigger alternator. Does it help? It can but eventually they both have to be recharged by the alternator while supporting gobs of electronics at the same time. However batteries and especially capacitors help smooth out the electrical signal from the alternator.
Also, every amplifier has capacitors in the power supply section.
I have a 2.5F cap that didn't do a damn thing. I did the alternator rewire and my headlight dimming has nearly disappeared.
