How big of an amp do you run? And what kind of car do you drive? A cap is more of a crutch. If you run a 400+ watt amp on a 60 amp alternator, you can get away with a cap on most occasions.
The amp is not bought yet, but some of the considerations are Soundstream, Hifonics, Infinity, all 1000 watts RMS or more. The car is a 98 Cadillac Seville.
A cap isn't a crutch and isn't meant to be used as a crutch. It'll only make any current problems that you're already having worse. A capacitor just makes it so when you get a bass hit that requires a whole lot of power to produce, your voltage doesn't sag. But if your alternator can't keep up to charge the capacitor back up after the hit, it's just straining your alternator that much more. You won't see your lights dim anymore, but that doesn't mean the problem was resolved. Quite the opposite.
easy: a capacitor filters AC ripple and decreases propogation delay. it does nothing for voltage rails or lack of current. you never "need" a capacitor for car audio electrical systems. you need a HO alternator if your voltage drops when the system is being used with the engine running or your lights dim when bass hits etc.. you're causing the amplifiers to clip when this happens from a lack of sufficient current causing voltage to drop which in turn will shred your speakers over time as well as damage the amplifiers.
watts = volts x amps is the formula you need to figure out if you need another alternator...figure roughly 35-45 extra amps is what your car allows...take your rms voltage (not max) and divide by 14.0 volts.
amps = watts/volts
ex: 2000 watts rms(not max) 14 volts
my alternator has 35 extra amps in the alternator. Do I need an upgrade?
2000/14.0 = 142.9 amps
Yes, I need an upgrade to roughly a 180-220 amp alternator.
This is just an example (2000 rms watts is quite alot)
Does the low amp alternator cause the noise for the system ??? I currently running my 60Amp (stock alternator). The weird thing that when I start the system in the morning, it's quiet (no noise). But After operate about haft an hour later, the system start getting whine noise (rev with engine). Eventhough I low the volumn all the way down, the noise is still there and some time it sound like Radio lost signal.
I run all my Power cable, speaker cable and audio signal separately. Also tried to bypass every audio component, unlug the antenna but the noise is still there. The Audio Cable is new.
The longer the car is operate, the noise is getting louder. This really p!ss me off.
I have a new HO alternator (180amp) will install this weekend. But it does seem like some electron magnetic field has built up inside the car or my batter power getting drain?? I have to leave the engine ON about a minute after shutdown the audio system otherwise the car doesn't have enough either amp/voltage to start after an hour or so (alarm inside the car)
Any though ?? or otherway of trouble shoot this issue would be appreciates. I have unhook the entire system and re-run all the cable from scrach twice.
Have you checked the battery? With a DMM, measure the voltage with engine off. It should read around 12.5v. With engine on, it should jump to 13.8v - 14.2v. When you hear the noise in the car, monitor the voltage. See if it falls within the safe range. If it's below or at 12.5v, then the alternator has a problem. If it moves up and down, it's still an alternator problem. If the car doesn't start, then you know the battery is at fault. With the DMM hooked up to the battery, apply a load, like a high powered spot light. See if the voltage drops by 1v or more. If it does, then the battery is just about dead. If you have a charger, charge the battery to full power and repeat the test. If it still fails, then replace it.
just go to pep boys or advance or similar and have them test the alternator and battery easiest way to see if both function properly under load. the DMM won't always tell you enough.
Best thing to use would be the little computer's that can monitor the whole electrical system. All you gotta do is hook it up to the battery, and can test it with the car off. Turn the car on and you can check the alternator and anything else drawing current. They work great, helped me know I need a new alt before my current one actually does blow on me. You can buy one, but their about $1500, so like Glass said, Pep Boys or something like that is your best bet.
It's called a batter-load tester. You can get a cheap one from Cummins for about $20. It has a composite capacitor in it, and can load test a battery, and when your car is running, it'll test the alternator too. Only thing it won't do is tell you what kind of condition your diodes are in, and you can't control the load. Is it worth it? Only if you do it a lot. I have a Snap-On unit that has all the bells and whistles, but I do this kind of work for a living :P.
