Capacitors

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Ravendarat

Platinum - Posts: 2,806

Joined: February 23, 2004

Location: Canada

Posted: February 15, 2005 at 2:21 PM / IP Logged

I think caps do indeed have a purpose. but everyone tries to use them to fix their lights dimming or use it to avoid buying a larger altenator. Simple fact is that if I am using my daily driver and are not experiencing any problems with my charging system at the levels I listen to my music then great, but if I also use that same car to compete with and the charging system cannot handle the strain of those big ass 50 hz hits, then a cap might very well help being I am only gonna run for 30 seconds and only need a couple burst durring that time. Its a shame that every second kid thinks they need a cap to put in their 94 cav because the lights blink, but thats word of mouth and thats marketing, plain and simple. As to the original question, you can add as many caps as you want to a system and they can be whatever sizes you want. I think you would be best off to post why you feel you need a cap first so we can figure out if its the best chicken soup for your soul

double-secret reverse-osmosis speaker-cone-induced high-level interference distortion, Its a killer

DYohn

Moderator - Posts: 10,741

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Joined: April 22, 2003

Location: Arizona, United States

Posted: February 15, 2005 at 2:23 PM / IP Logged

Five years ago I helped build a 20,000 watt system in a Suburban for a radio station. No caps. None needed (six 300-amp alternators and six batteries. Oh, and an onboard 120V power supply and outboard generator as a backup.)

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Ravendarat

Platinum - Posts: 2,806

Joined: February 23, 2004

Location: Canada

Posted: February 15, 2005 at 2:34 PM / IP Logged

Mabye Ill just do that on my next system, that sounds way easier Capacitors - Page 2 -- posted image.

double-secret reverse-osmosis speaker-cone-induced high-level interference distortion, Its a killer

Edicius

Copper - Posts: 90

Joined: March 11, 2003

Location: Georgia, United States

Posted: February 15, 2005 at 2:45 PM / IP Logged

OK, don't read the next sentence and judge me before reading the whole post, that should go without saying but I've had people do that before. Basically I am trying to avoid buying a bigger alternator, but hear me out first. I have not installed my system yet and therefore do not know if I will have a problem. I have a 2002 Chrysler PT Cruiser and I want to add a power hx2 sub from Rockford Fosgate which is 1000 watts RMS. I was planning on getting an Audiobahn a1300hct which can run at 1200 watts RMS x 1 at 1 ohm. What I have been told is basically if I am borderline and almost in need of a bigger alternator then a capacitor would help keep me farther towards the safe side. I hope that I wrote that where it makes as much sense as it does in my head.

DYohn

Moderator - Posts: 10,741

Joined: April 22, 2003

Location: Arizona, United States

Posted: February 15, 2005 at 3:19 PM / IP Logged

A properly used stiffening capacitor can help an amplifier sustain peak output during short music transients. It is designed to help the amplifier's power supply maintain peak rail voltage. It helps in vehicles where the max current draw of the system is at or close to the max capcity of the alternator, since a cap can discharge more quickly than an alternator can supply current.

Assuming your amplifier can actually produce 1200 watts (which is another topic altogether) it will require around 175 amps from your electrical system when it peaks. The continuous draw of that size amplifier would be about 60 amps. This means you need to rate your power cable and fuse for the peak (175 amps) and your alternator will be required to produce ~60 amps continuously over what the vehicle normally requires to run. Since most car alternators have about a 40% reserve capacity (meaning the normal vehicle loads use up about 60% of the alternator's total capacity and you have 40% left for peaks and add-ons) you will need an alternator rated at around 140 amps. THEN a cap can help supply the 175 amp peak and help the amplifier sustain its output and keep your lights from dimming during transient peaks. But only after the alternator is already big enough.

I doubt the OEM alternator in a PT Cruiser is rated at 140 amps. I doubt you are "at the edge." I suspect you are way over it.

This, my friend, is the down-side and hidden cost for wanting to run such a large amplifier.

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Edicius

Copper - Posts: 90

Joined: March 11, 2003

Location: Georgia, United States

Posted: February 15, 2005 at 4:38 PM / IP Logged

I believe the OEM alternator is 110 amps.

Edicius

Copper - Posts: 90

Joined: March 11, 2003

Location: Georgia, United States

Posted: February 15, 2005 at 5:22 PM / IP Logged

Can you tell me what the maximum wattage a 200 amp alternator could handle with a 5 farad capacitor?

Drewt

Copper - Posts: 183

Joined: January 04, 2005

Location: United States

Posted: February 15, 2005 at 7:00 PM / IP Logged

it all depends on the amplifier

My amplifier draws a max of 60 amps (since it has 2 30-amp fuses on it :) ). Look at the fuses on the amplifier (if it has any), and know that it won't draw over that many amps....

The cap won't let you run a bigger amp. I have a cap, and it does help, but what it does is keeps my amplifier at about 13.7 volts during hard hits (and I'm not talking about 50Hz hits, I'm talking about 20 or so Hz hits....lol)

Ravendarat

Platinum - Posts: 2,806

Joined: February 23, 2004

Location: Canada

Posted: February 15, 2005 at 10:54 PM / IP Logged

I dont know if that was a shot at me but just in case it was, I understand that 50 hz is not a low hit and is no where near the hardest frequency to reproduce in a car, just that serious spl systems, esspecially one not wonders tend to be in the 50-65 hz range. Just clearing myself up here

double-secret reverse-osmosis speaker-cone-induced high-level interference distortion, Its a killer

kfr01

Gold - Posts: 2,121

Joined: April 30, 2003

Posted: February 16, 2005 at 1:31 AM / IP Logged

Edicius: Why are you interested in a second rate solution that probably won't even work for a small difference in money?

Buy an alternator or go with less wattage. I think a capacitor would be a complete waste of money for you.

New Project: 2003 Pathfinder

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