Information About Capacitors

[basicxj]

Originally Posted by benahn7 Capacitors are used for many applications and they do exactly what they are designed to do. They may be considered junk by someone who knows nothing about car audio and just repeats stupid comments. A capacitor is an electrical storage device just like a battery is a storage device. One device releases power faster than the other and one charges faster than the other. Which one is best depends on the application needed. Let’s say you only need a small amount of extra storage in your Honda civic to keep your lights from diming why wouldn’t you use a cap its going to be a lot less expensive than an extra battery plus wire and terminals. It takes a lot less space to use a cap and it weighs a lot less. Lots of people used to swear that the world was flat and you could fall off the edge. Its just knowing what you are talking about.

You might experience dimming with obsolete/old/cheap & nasty amplifier designs using what is considered a modest amount of amplifier power, but might see no dimming using similar amounts of amplifier power from superior amplifier designs in the same vehicle. Most of today's reputable amps of good quality already have enough capacitance under the heat sink as part of their circuit design, and should you experience severe dimming with one of these, there is a good chance you need more current than the vehicle's electrical system can truly provide for the vehicle and added accessories- adding an additional capacitor to such a current deficit may be akin to putting a band-aid on a gunshot wound, in that it will do little if anything to stop the problem when adding more current and/or eliminating bottlenecks in the OEM grounding scheme is the real long term solution.

A capacitor can only make up for variations in current of extremely short duration such as a quick kick-drum hit as it discharges almost instantaneously, but will do nothing for a sustained low bass note that causes dimming or extended voltage drop as it will have completely discharged at the beginning of such a note. If voltage has dropped beyond a fraction of a second, a capacitor will not be able to re-charge until the condition has rectified itself and the system no longer has such a deficit and has returned to normal operating voltage well above the battery's resting voltage. The problem with capacitors is that they are often misrepresented by those who sell them and by those who use them as a be all/end all "fix" for strapping bug systems into cars with tiny electrical systems...it will be of no help to someone with 200A worth of added draw on an 80A alternator who intends to blast the system for extended periods. If someone only wants a millisecond of stiffening in their electrical system for power-robbing transients that last a fraction of a second, adding a capacitor may be something to consider.

[X2E]

IMHO, the amplifier power supply should hold enough in reserve (on-board caps) after initial charging to maintain (basically, to buffer the gaps) a stable state of operation and should not show any signs of dimming if the alternator is capable of keeping up with the mean rate of power consumption. Additional batteries (XS Power, etc.) are a plus, but only with adequate charging potential, and they also add to the overall drain on the charging system, since any conversion of power comes with the cost of a loss due to heat and inefficiency.

The simple truth is that if you cannot charge at the rate you consume amperage (plus conversion losses), no amount of capacitors nor batteries will help you, and you'll likely spend more money on chasing the side-effects than you would by upgrading your alternator and charging cables as you should have done to begin with.

[benahn7]

Originally Posted by X2E IMHO, the amplifier power supply should hold enough in reserve (on-board caps) after initial charging to maintain (basically, to buffer the gaps) a stable state of operation and should not show any signs of dimming if the alternator is capable of keeping up with the mean rate of power consumption. Additional batteries (XS Power, etc.) are a plus, but only with adequate charging potential, and they also add to the overall drain on the charging system, since any conversion of power comes with the cost of a loss due to heat and inefficiency. The simple truth is that if you cannot charge at the rate you consume amperage (plus conversion losses), no amount of capacitors nor batteries will help you, and you'll likely spend more money on chasing the side-effects than you would by upgrading your alternator and charging cables as you should have done to begin with.

The sad thing about this topic is that capacitors sold for car audio use really are weak little parasites that could only stiffen the smallest systems. The capacitors that are being used by many pros in car audio competition are not car audio caps at all they are Maxwell supper caps used for regenerative hybrids. A small bank the size of a car battery will out power six 850 CCA stingers for a 3 second burp. That’s a whole lot of time at the level of draw being used. it would take about 1000 car audio caps to even come close.

[X2E]

Agreed, benahn7.

I used to use caps (back in the late '80s when they came into fashion being used in many IASCA systems, but I didn't know any better at the time, and caps were all the rage), but I currently do not have any use for them, nor can I imagine a proper application for them in any "daily driver". They can have a practical use in extremely high current demand situations where batteries cannot release the demanded current as fast as a cap (honestly though folks, how many microseconds are we dealing with?), but only in conjunction with many, many high performance batteries, and usually multiple high amperage alternators, and usually only in a DB Drag sort of system (something you wouldn't want to listen to on a daily basis anyway).

However, I'm an average guy, and I've been using a couple of XS Power batteries (I'd suppose a decent "rule of thumb" is one per thousand watts for the average Joe) along with a 275 amp alternator. I've run my system at sound pressures as high as the My Ford Touch system in my car will tolerate (without whacking out the display, that is) at night, with lights on, at idle, and AC running... with no dimming at all (as far as my SPL-affected blurry vision can discern, anyway) without the use of caps. If that won't please almost anyone, damn...

As you've accurately noted, caps are pretty much a waste of time and money for the vast majority of folks unless you're running around with more dollars than sense.

[iceberg8389]

I have been going back and forth as to whether or not i should incorporate a cap into my system. however, after reading this i think its clear it would be a waste of time and money to do so. if someone could just confirm my conclusion i would appreciate it.

i am running a JL 500/1 slash mono amp into two 12 JL w0v3's mounted in a basswedge ported box. i am powering/grounding the amp with 4g wiring. i have the amp set at the +12db setting, and at full volume with lights and heat on i get no dimming at all.

i was surprised to learn that the factory alternator on my 2007 Audi is actually 200 amps. probably because of all the electronic systems built into the vehicle from the factory. i recently had the recharging system checked when i had the entire vehicle inspected after purchase and it tested out fine at full charging capacity and functionality. i also have access to a digital aftermarket voltage gauge, among others, via OBDII bluetooth data with which i use the Torque app on android to monitor all operating systems. this program indicates just above 12v consistantly even with lights, heat, car running and radio cranked with no significant drop. it fluctuates minimally but never drops below 12.

given all this information, i feel my system is pretty stable as is and a capacitor is not needed.

[MOSFET]

Not sure if I have much too add here as everything has probably been said at least 10 times already. But I can offer my own conclusions after having been using caps for over 20 years now.

First, I happen to know FOR A FACT that the 1 farad for every 1000kW of power guideline was based more on marketing than hard data. In 1993 I used to have my installations done at Magnolia Hi-Fi (before I started doing all my own installs around 2000) in Beaverton OR. There was an installer named Glen Gable who became a good friend of mine and was also a good friend of David Navone, of Autosound 2000. David had told Glen that with capacitors, more is always better and the number of farads needed for any given system depended on MUCH more than simply the amount of amplifier power. I think anyone reading this has already figured this one out.

Capacitors ARE, FOR THE RECORD, an ingenious way of helping with the transient nature of music and therefore the transient demand for power of amplifiers (unless you listen to test tones), unlike every other electrical device in a car (like headlights) that demand a CONSTANT flow of current. HOWEVER, there are SO MANY OTHER FACTORS that must be considered (the built-in capacitance and efficency of a given amplifier, the "extra" current available from car to car from a stock alternator, the type of music one listens to, and on and on) that any formula is pretty much useless. The problem was that when the "stiffening capacitor" was introduced by autosound 2000, they were very expensive ($100 for every 1/2 farad, I KNOW, I BOUGHT TWO and gold-plated buss-bars) and they couldn't simply say, "Buy as many as you can possibly afford and HOPE they help....". I'm an MBA folks (worked as a college professor at the Univeristy of Portland and in the marketing dept. of Phoenix Gold), and "buy as many as you can afford" is not a good "pitch". So they needed a general formula, something simple, and the one farad for every 1000 watts was born. Also, it should be noted that Autosound 2000 did not invent this idea, they just were the first to brand it, but car audio competitors for YEARS had been stringing large electrolytic capacitors together in parellel to help beef up their amplifiers own internal caps. I recall competitors in the 80's with dozens OR MORE of smaller (.25 farad or less) caps strung together as most EE's at that time believed the smaller the capacitor, the quicker the charge/discharge. Although this is no doubt true, the differences are for all practical applications impercepeptable.

Having said that, my own experience is that THEY REALLY DO HELP!!! But I have found that The Big Three upgrades AND a battery with a very low internal resitance like the Optima Yellow top, help keep voltages higher and make a bigger difference than mearly adding several one farad caps. In fact, I did my own testing with a 1000 watt system in my 1999 Subauru Forester and found that it wasn't until I had added at least four farads that I perceived any difference.

There was a FANTASTIC article written around 2000 in CA&E I believe where a bunch of caps were compared and measured. Everything from a basic 1 farad Lightening cap to a 100 farad Batcap was compared and measured using a host of test music and dummy loads. The results were facinating. it appeared that ON PAPER using test equipment, there was little improvement until one got beyond 20 farads or so.

So take EVERYTHING regarding caps with a grain of salt. Like the high-end home audio world, things can get pretty subjective. People hear what they want to hear, and if they believe the $200 they spent on capacitors will help the sound, they will likely convince themselves IT DOES. I am as guilty of this as the next guy. And again, the THEORY behind caps is sound. Just as the theory of silver audio interconnects and speaker wire is better than copper IS SOUND as silver is a better conductor of electricity. However, can a person ACTUALLY HEAR THE DIFFERENCE? Well, often they are SURE they do, even when the test data is a bit more dubious. I think caps, to some degree, are similar.

Anyway, that is my $.02 on the subject,
MOSFET

[mariano]

Thanks for this nice info about Capacitors.

[autotinting]

My larger concern is however well would it not begin an oversized motor, particularly a stubborn one that you simply have to be compelled to crank over a lot?
I think that these capacitors have the power to produce an over quantity of amps required to quickly flip a low engine.
What if you required to crank it over for a sort of a minute making an attempt to induce your cold carbureted engine to start?

[basicxj]

Originally Posted by autotinting My larger concern is however well would it not begin an oversized motor, particularly a stubborn one that you simply have to be compelled to crank over a lot? I think that these capacitors have the power to produce an over quantity of amps required to quickly flip a low engine. What if you required to crank it over for a sort of a minute making an attempt to induce your cold carbureted engine to start?

Say what?

[MOSFET]

Originally Posted by autotinting My larger concern is however well would it not begin an oversized motor, particularly a stubborn one that you simply have to be compelled to crank over a lot? I think that these capacitors have the power to produce an over quantity of amps required to quickly flip a low engine. What if you required to crank it over for a sort of a minute making an attempt to induce your cold carbureted engine to start?

Are you in the right forum dude? This is about capacitors and their effects on car-audio power amplifiers for music reproduction. It really has nothing to do with engine performance.

[Audioholic]

Amplifiers have capacitors in their input stage. If your system would gain any noticeable performance increase by adding external caps, its probably just a sign that you have a low quality amplifier.

[SPL_Krayzie112]

Will there be way of hard-wiring external caps into the PCB that way the external capacitor works "seamlessly" with the rest of the on-board circuitry?

[Audioholic]

Originally Posted by SPL_Krayzie112 Will there be way of hard-wiring external caps into the PCB that way the external capacitor works "seamlessly" with the rest of the on-board circuitry?

The caps on the input stage of an amplifier are a bank of much smaller and more efficient caps than the ones we tend to see used for external caps in car audio. Again, if your amplifier is designed sufficiently, there should be no need for adding a cap to the mix.