What is a Good Capacitor?

"Stingpro" .....I just did a quick look-through on a google search, and I know enough about that POS already to say stay away from that worthless junk.  Crap with a rip-off name.  If you see a capacitor that no respectable retailer will carry, but can be found for "unbelievable low prices" at an assortment of no-name web sites, stay away.  Rushman said it. "You get what you pay for"

https://getsounds.com/capacitors/capacitors_2a.html .....for  example....

dxav]s wrote:

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eedwayaudio1 is right people. There are only 3 or 4 capacitor manufacturers in the country. They all are made the same way (just increasing the density for higher ratings), and they put a sticker from any brand on them and ship them out. I have found capacitors at just yards that have outperformed some brand new caps from big name companies. Capacitors aren't component driven (a capcitor is just 2 plates of metal with a dialectric in between). There is only one way to make it. So they make them all the same way. You are simply paying for the name.

DXAV

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That's not entirely correct.  One critical parameter of capacitors (and what differentiates a poor one from a better one) is its ESR (equivalent series resistance.)  Look for caps with the lowest possible ESR.  This enables them to charge and discharge faster (and thus perform better in high frequency operation.)  Cheap caps have poor internal construction and higher ESR values.  The most common method for determining capacitor failure is measureing high (sometimes infinity) ESR.  You need a specialized tester to measurte ESR, by the way.  It cannot be done with a standard multimetrer.

Has anyone ever discharged a fully charged 1 farad cap?  LOL that would be a site to see.  I've played with microfarad caps but nothing big.  Anyways.  What's probably the minimum wattage that a cap would do any good?  500 watts?  1000?

Does anyone how many amps a battery can instantaneously discharge?  It's not the CCA rating is it?  If it cannot discharge enough amps than what the amplifiers are demanding then connecting batterys in parallel like the pro's do will give you more amps thus eliminating the need of a capacitor right.

A guy at interstate batteries told me that the optima blue top I have acted as a big capacitor.  Do the optimas have a lower internal resistance than stock batteries?  How does the internal resistance compare to that of a capacitor?

dxav]D wrote:

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I bore people, or flex my brain?

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so i'm guessing that i should not worry about upgrading the battery?

how do i go about figuring out how many amps i'm going to add to the system?

should i get all my parts first then worry about the wiring?

On most newer cars, adding a 1000w amp would probably not require an alternator upgrade right.  That's 1000w peak so RMS is probably less than 500w.  I'm running a RF P8002 with a 4ohm load which RMS 400W and I have 2 smaller RF amps with 45w x2 RMS.  That's 600W RMS and my lights are not dimming on my huyndai elantra.  I have a second battery which I installed for playing with the car off. 

Every car is different so maybe they designed mine with a bit more reserve.  Does a cap really improve bass responce or are the internal caps of an amplifier sufficient for spontaneous bass notes?

Wiseguy wrote:

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correct me if im wrong but can a battery be considered as one large capacitor?

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I suppose in a very general, basic layman's terms sort of way it could, but the two are entirely different types of devices and operate in entirely different ways.  A battery produces energy through an electro-chemical reaction, releasing voltage potential from the interaction of several compounds, while a capacitor simply stores a difference in charge potential.  A battery actually converts physical matter into electricity and back through a chemical reaction, while a capacitor does nothing more than allow an electric charge to build up on a plate.  A battery will generate its voltage all by itself, a cpacitor must be continually supplied with energy to maintain the charge potential across its plates.  A battery is a generator, a capacitor holds static electricity.  Without external influences, a battery can sit for very long periods of time and still have its ability to convert chemisrty into electricity, while a capacitor will eventually dissipate the temporary chages it stores on one plate to the other and it will equalize.  So, wihile on a very, very basic usage level both devices "store energy," a battery is considered an actual power source while a capacitor is simply a temporary storage area.

I would start with a bigger alt. everthing electrical in a car depends on the alt (radio, amp, battery, cap) it all is supported by the alt. Thats were I would start anyway..

i do have a 130amp alternator, so with the amp cranked (which it never really is), it would use 60amps.  So now i've got 70amps left to run my day lights, everything else is off. (well..  im sure theres a bit needed for computer and such, but thats minimal).  Even if I was left with half that, I would think that my headlights would be ok.

As for the cap (to keep within the topic of the forum), I found it made a big difference to the clarity of the bass produced.  I hooked up a volt meter before and after, and found it did even out the voltage spikes a lot.  Some things I have heard of that make caps not work so well include:
-Not grounding the cap seperatly from your amp
-Using too small a cap (0.5 farad cap will not help a 1000W system)
-Lastly, you are supposed to fuse both ends of your main power cable with a cap installed.  Sounds weird, but it you are in an accident, ar have a power wires insulation wear off from rubbing somewhere, along the lenght of you car, the fuse next to your battery will pop, but you will still get a nasty back charge from the cap - which can create some unwanted fireworks.  So you should also have a fuse right next to your cap.  Problem is, some guys have put the fuse in between the cap and the amp, and apparently due to the fuses higher internal resistance, the cap wont function properly. 

[GRND]---[BAT]---[FUSE]---------------------------------------[FUSE]----[CAP]---[AMP]---[GRND]
                                                                                                                        |
                                                                                                                        |
                                                                                                                  [GRND]

"Battery is the place for the powerwire. If you went to the alt. you would have power spiking problems, but also you wouldn't be able to run your system if the car wasn't on"

FALSE

    OK I have read thru this whole section on capasitors and have gotten alot of ideas. I just installed a cap in mine pathfinder it is a .5 cap and I have two amps hooked up to it  ( 400w and 100w ) and my cross over as well.

  Is this ok ? I also only have the fuse close to the battery shoul I add a second one ?

  I just finished my install yeaterday and still have not check for the lights dimming but I will tonight to see if it has helped at all?

  As far a charging the cap before use I followed the instructions of putting the resitor between the + wire and the cap ( by the way it was not a few seconds like they say) It took a coulpe of minuets to charge . I tested the battery and got a little over 12volts which is what my cap is at now. Is this the correct way to do it ?

Would a cap do any good w/ 500 watts?  Sounds kinda nominal for a car of any sort of recent production years.  The car w/ a decent bat should be able to support a 500 watts system right?  My friend's got a .5 farad cap for a 600 watt system.  We disconected it and it made no difference.  I think he wasted the $70 (or more) he spent on it.

   Well I only paid $45 for mine and have not had the chance to see if is makes a difference .

 So you are saying the my truck should be able to hadel the 500 watts? I have a 96 nissan pathfinder. My alt. I belive is reated at 90 amp I think?????  I had the system hooked up with out the cap and had the lights dimming .. Going to see what it does now... I am running 4ga pwr to the cap and 8ga to the amps and ground .... is that ok ?

    So 4ga to the cap then 8ga out to amps is ok ?   I will be upgrading my negative to my bat soon . Will keep you posted . I have noticed a nicer bass sound since the cap but I thing my sub out on the EQ is acting up is it is in and out at time but that is for a different post..LOL But it is cleaner sounding ....

  As soon as the wife lets me spend more money I will do that but at the moment I am cut off....LOL

I am runnin the Memphis Mojo at 2000 watts, no need for me to daisy chain 2 batts to get the 2400, so do I need 2 or 3 farad?