What is a Farad?
Printed From: the12volt.com
Forum Name: General Discussion
Forum Discription: General Mobile Electronics Questions and Answers
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=52366
Printed Date: April 25, 2024 at 12:40 PM
Topic: What is a Farad?
Posted By: 83malibuRida
Subject: What is a Farad?
Date Posted: March 22, 2005 at 12:01 PM
in terms of being a unit of energy? like watt or joule(sc)
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Nick Scott
Replies:
Posted By: chrisne77
Date Posted: March 22, 2005 at 12:10 PM
The unit of capacitance equal to the capacitance of a capacitor between whose plates there appears a potential of one volt when it is charged by one coulomb of electricity.
Posted By: 83malibuRida
Date Posted: March 22, 2005 at 1:12 PM
laymens term please, how can one determine how many farad caps would be needed to equal the current draw from the amps.
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Nick Scott
Posted By: oonikfraleyoo
Date Posted: March 23, 2005 at 12:04 AM
Thats easy. NONE! ------------- Nik
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Posted By: chrisne77
Date Posted: March 23, 2005 at 9:36 AM
I have never used a cap in a system. I understand what a cap's purpose is. It makes more sense to me to upgrade the alternator and maybe add an extra battery. I know that this is more expensive, but I think that is the ultimate solution.
Posted By: Master Asylum
Date Posted: March 23, 2005 at 11:12 AM
Yeah, it's purpose is to waste $$$, like Alterstart(end rip). And caps aren't any cheaper if you think of the effects. Imagine the more its gonna strain your alternate, thus killing it faster. A replacement will make up for the difference and anyone who knows a thing about audio will laugh at you because you're gonna be buying another one eventually. Just get the alt upfront, just stay the hell away from Alterstart. LOCAL=GOOD. PROFESSIONAL=GOOD. Trust me, its worth it.
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Posted By: Mad Scientists
Date Posted: March 26, 2005 at 12:44 PM
Master Asylum wrote:
Yeah, it's purpose is to waste $$$, like Alterstart(end rip). And caps aren't any cheaper if you think of the effects. Imagine the more its gonna strain your alternate, thus killing it faster. A replacement will make up for the difference and anyone who knows a thing about audio will laugh at you because you're gonna be buying another one eventually. Just get the alt upfront, just stay the hell away from Alterstart. LOCAL=GOOD. PROFESSIONAL=GOOD. Trust me, its worth it.
How's the cap going to strain the alternator more?.. Jim
Posted By: thepyrofish
Date Posted: March 27, 2005 at 11:02 PM
Something has to charge the cap.
Posted By: Mad Scientists
Date Posted: April 01, 2005 at 6:50 PM
How much power is it going to take to charge a cap?.. besides, once it's charged there's no more demand on the charging system from the cap. I imagine that running the high beams will draw more power from the alternator.. Jim
Posted By: geepherder
Date Posted: April 01, 2005 at 8:10 PM
Of course this is probably not going to happen, I'm simply playing devil's advocate. Let's imagine your cap depleting itself completely (in theory) on a heavy bass note. Now, with a completely discharged cap, you've effectively shorted the alternator output to ground! (That's why you charge caps with a test light in series- so it's not a direct short to begin with.) Yes, your fuse should pop or circuit breaker open, but if only for an instant at a time, those heavy spikes will destroy an alternator quickly. With the absence of a cap, this would not happen- you'd simply have appreciable voltage drops if the alternator was not up to par. In reality, you'll probably never fully discharge a cap on a heavy beat, or you've proven yourself a complete moron by severely overloading the car's electrical system. On a side note- I have a cap in my setup, which I feel does it's intended purpose- supply a steadier voltage to my equipment, and it's not leaving any time soon. ------------- My ex once told me I have a perfect face for radio.
Posted By: Mad Scientists
Date Posted: April 02, 2005 at 5:55 PM
Oh.. devil's advocate.. I *like* this game.. The cap is wired in parallel with the alternator and the battery. describe a situation where the cap could become completely discharged without the battery and alternator being affected. At most I'd suspect you'd see some voltage drop in the wiring, but nothing close to 0v.. I'm thinking that the cap would actually help reduce the heavy spikes that the alternator might see during heavy base.. isn't the reason for installing a cap is to help eliminate the dimming light effect?.. Jim
Posted By: 83malibuRida
Date Posted: April 03, 2005 at 5:39 AM
hmmm....he has a point
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Nick Scott
Posted By: DYohn
Date Posted: April 04, 2005 at 5:15 PM
FYI, it is impossible for a capacitor to "become completely dischsrged" unless the battery is also "completely dischsrged" and the alternator is producing zero volts. A capacitor will maintain whatever system voltage happens to be. ------------- Support the12volt.com
Posted By: Mad Scientists
Date Posted: April 04, 2005 at 7:27 PM
Exactly.. under normal operating conditions the battery, alternator, and cap should all be around the same voltage.. excluding voltage drop in the wiring. Jim
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