Caps...Yay Or Nay?

[Bumpin Expo]

What are ur guys takes on caps? Im gettin an upgraded battery but im thinkin of gettin a cap also. What do u guys think i shoudl do?>

[MDIFYTD]

I would wait to you have your entire system installed to see what kind of strain you're putting on your charging system. If it's still weak then get a nice big alternator. I don't really care for caps, they're just bandaids really.

[Miles]

just save the money you'd be spending on a cap... and buy an alternator. cap aint gonna do squat.

[Kirk]

Originally posted by saggleman
just save the money you'd be spending on a cap... and buy an alternator. cap aint gonna do squat.

Coming from someone who doesn't know jack shit himself. :roll:

Caps are great for solving certain kinds of problems...

What you need to do is figure out what issues you have, and what will solve it. A good logging voltmeter is the perfect tool for troubleshooting your amp rack wiring, but any reasonably good analog meter will do fine.

First off, set up the pieces. Start the car, and have someone keep it at 2500 RPM or so. (I used 2800, because that's where it stayed when I proped the gas pedal with a stick. :) ) Turn on accessories like A/C (or heat, whichever is appropriate) and turn the fan on high, too.

Now pick something with a fair amount of bass. Probably in the heavier range of your listening preference. If you don't tend to listen to too much bass, then borrow something. :) Turn it up!

Measure the voltage at the amplifier terminals. (Not just the sub amplifier, check all system amps!)

Whenever a bass note hits, you will probably get a dip in voltage. Record the peaks at both the top and the bottom of the dip. While maintaning listening level and RPM check again in a couple of minutes. (5 or more)

Now, here's where the diagnosis comes into effect.

If your peak voltage is below 13.5V in your first test, then your wiring is probably weak and should be upgraded, or you left hte tunes cranked for too long before you started your test. :) Your amp is choking on what you can feed it through the wire that you've run. Of course this assumes that your charging system is working properly int he first place. :) In my case, 13.8V -- Not a problem.

If the peak voltage is lower in the second test than it is in the first test, your amps are drawing more current than your electrical system can provide. Some drop might be expected, but anything noticeable indicates that your electrical system is overloaded. (This is why keeping the engine at or slightly below highway cruising RPM is needed -- to gauge how effective the alternator is.) Again, in my case, 13.8V -- Not a problem.

In either of these cases, a capacitor will be of no use to you, although it will still resolve the following:

Now, it's time to look at the dips in voltage whent he bass notes hit. In both your tests, they should be about the same magnitude. In general, the rule of thumb that I've seen get reasonable results is 1F for every 1V range for every 1kW of RMS class B amplifier power. If your voltage range is larger, you need more, similarly, if your amount of amplifier power is greater, then you need more. Note: Class "D" subwoofer amplifiers take considerably less current than class "B" amplifiers. (If you have class "A" amplifiers, then you ought to KNOW what your amp needs to feed it! Class A amplifiers need completely different troubleshooting, because they drain power differently than class "B" and class "D" amps do.) For class "D" I'd say that you'd take it at a 1/4 value for that rule of thumb, so 1000W RMS of class "D" power can be treated as 250W RMS of class "B". -- That's not to say that it's less output power, but because it's more efficient, it IS less INPUT power.

The reason is simple. Long wires act as inductors, so the big long power wire to your amp rack resists changes in load. The capacitor, in parallel with the amplifier, and at the amplifier end, balances the changes out, by supplying the transient current needs (Note: Not voltage, but CURRENT) when the wire can't keep up. By doing this, it helps regulate the demand on the electrical system, which can mask signs of an inadequate electrical system. If the voltage dips aren't just happening at the amplifier, but, through the system's main wire, are happening throughout the car's electrical system, then a big capacitor will, in effect, do the same thing for the whole car. Since the whole car represents a peak load of less than 1kW (Unless something is SERIOUSLY wrong) it can stabilise the voltage, albeit at a lower than expected value. This is great news for the people selling 5F capacitors to kids with 300W amps, because it makes it SEEM like the cap is halping the alternator, when in fact, nothing could be further fromthe truth...

[Bumpin Expo]

shit my lights are jus dimming LoL but tomarrow ill take a meter out there and test it like u said ill tell u the results thanks man

[Miles]

hey kirk... look at me! i can copy and paste things from other websites too!!!

http://www.welcometotheden.8k.com/caraudio/Captest.pdf

fucking jackass

[Bumpin Expo]

ahhh

[aaron1017]

Hmmm, I would of thought Jesse would be the first one to reply to this thread.............:o :o :o :o :o :o :o :o

Caps = no... better battery = yes. If ya know aobut electronic decently.. the decision would be easy.

[Bumpin Expo]

Originally posted by aaron1017
Hmmm, I would of thought Jesse would be the first one to reply to this thread.............:o :o :o :o :o :o :o :o

Caps = no... better battery = yes. If ya know aobut electronic decently.. the decision would be easy.

WELLLLLL I am already getting a battery, i was wondering if getting a cap ALSO would help? And obviously i didnt know too much on caps, so the decision wasnt easy and thats why i asked, but thanks for the info bud :dunce: oh and 93ex thanks for all the info, who cares if it was copy and pasted. I think ur the only one on there thats been so helpful and hasnt been a dick. Thanks and sorry for getting u :flamed:

[aaron1017]

A cap will help for a 1/1000000th second bass-line. After that the cap are useless since they discharge ALL of their stored energy in a nanosecond. If you had a couple hundred Farads of storage, it might help for a second or so. But all that energy would take a while to store up, rendering it useless. I would just recommend getting a battery first and then a high powered alternator if you are serious about audio.

In order of best to leasy helpful:
1. HO Alternator
2. High Current battery (Yellow top Optima). The rating on batteries gets difficult and I won't get into the discussion on plate thickness, CCA's, RC's, etc.
3. Cap (mostly worthless)

[93ex]

Originally posted by Afboy143
WELLLLLL I am already getting a battery, i was wondering if getting a cap ALSO would help? And obviously i didnt know too much on caps, so the decision wasnt easy and thats why i asked, but thanks for the info bud :dunce: oh and 93ex thanks for all the info, who cares if it was copy and pasted. I think ur the only one on there thats been so helpful and hasnt been a dick. Thanks and sorry for getting u :flamed:

no problem :dunno: even tho i hate caps and agree with miles and aaron.

edit - since the cap can only get power as fast as the battery can provide it, the amps will only get the power as fast as the cap can provide it too, which in turn, is only as fast as the battery can provide it.. which is how well the battery is geting charged..which boils down to what? not the capacitor

[Kirk]

Originally posted by saggleman
hey kirk... look at me! i can copy and paste things from other websites too!!!

http://www.welcometotheden.8k.com/caraudio/Captest.pdf

fucking jackass

Did you even read the website you posted? :lol: :lol: :lol: Again you make an ass out of yourself.... keep dreaming buddy :lol:

[Bumpin Expo]

WHOOPS, i didnt mean to give props to 93ex, i meant supra kid.Hes always helpful and never a dick. MY BAd and yeah i c that caps suck now. I guess im not gettin one now, i might go out and get the alt rewound.

[93ex]

Originally posted by Afboy143
WHOOPS, i didnt mean to give props to 93ex, i meant supra kid.Hes always helpful and never a dick. MY BAd and yeah i c that caps suck now. I guess im not gettin one now, i might go out and get the alt rewound.

good, cause im never helpful and ayways a dick

[MDIFYTD]

me too

[TBSpyder]

Caps always seem to get mixed reviews. Some say they work...some say they don't. I've also heard that they're really only beneficial on SQ setups being an SPL setup would drain it so quickly and not have the time to recharge it thoroughly. It's worth a try, and either way...if you got the kind with a digital meter on top it'd be nice to monitor your electrical system.

Your alternator is the key though.

[aaron1017]

You can have my super generic brand 1 Farad Cap that i got for a few bucks if you bring me the following (or 5 bucks):

Foot Long Subway Club on Itialian Herb and Cheese
with the following toppings:
American Cheese
Mayo
Little bit of Mustard
Lots of SouthWest Sauce
Lettuce
Onions
Bell Peppers
Oil
Vinegar
Salt n' Peppa
Oregeno


edit: nothing wrong with it, just taking up space and caps dont do much of anything...

[TBSpyder]

Originally posted by aaron1017
You can have my super generic brand 1 Farad Cap that i got for a few bucks if you bring me the following (or 5 bucks):

Foot Long Subway Club on Itialian Herb and Cheese
with the following toppings:
American Cheese
Mayo
Little bit of Mustard
Lots of SouthWest Sauce
Lettuce
Onions
Bell Peppers
Oil
Vinegar
Salt n' Peppa
Oregeno


:lol:

[Miles]

Originally posted by SupraKid
Did you even read the website you posted? :lol: :lol: :lol: Again you make an ass out of yourself.... keep dreaming buddy :lol:

The red curve seems
to overlay the yellow except that the actual peaks don’t rise as fast or as high during
the brief quiet moments. I feel this would be due to the alternator having to recharge
the cap. The voltage on loud passages hovered around 12.5 volts. The computer
averaged calculations for this test show the average voltage to be 12.878 volts. I see
no meaningful differences with or without the cap. I certainly don’t see the voltage
sitting solid at 14 volts.

sounds to me like it backs up my "caps don't do a god damned thing" position :)

[Miles]

Originally posted by SupraKid
If your peak voltage is below 13.5V in your first test, then your wiring is probably weak and should be upgraded, or you left hte tunes cranked for too long before you started your test. :) Your amp is choking on what you can feed it through the wire that you've run. Of course this assumes that your charging system is working properly int he first place. :) In my case, 13.8V -- Not a problem.

If the peak voltage is lower in the second test than it is in the first test, your amps are drawing more current than your electrical system can provide. Some drop might be expected, but anything noticeable indicates that your electrical system is overloaded. (This is why keeping the engine at or slightly below highway cruising RPM is needed -- to gauge how effective the alternator is.) Again, in my case, 13.8V -- Not a problem.

In either of these cases, a capacitor will be of no use to you,



just out of curiosity, how come you have a cap?

[Kirk]

Originally posted by saggleman
just out of curiosity, how come you have a cap?

Originally posted by TBSpyder
Your alternator is the key though.

An alternator upgrade provides more current, preventing the battery from draining long-term. This is what you need if your battery goes dead after playing the stereo for a long time while the engine is running.

"Lights dimming" when the bass notes hit is a different problem, and is caused by the battery and alternator not keeping up to the transient demands of the system. For this kind of problem, a capacitor will do an excellent job of helping the problem by evening out the system demands. Increasing alternator output has little or no effect on this problem.

One "alternator" upgrade that can help is to improve the voltage regulator. The voltage regulator needs to be able to react to changes in demands on the electrical system, and most of them just aren't fast enough. The battery also has a reaction time, but it's a lot faster than the regulator, and except in extreme cases, can usually keep up. One of the primary reasons why an Optima battery is better for audio systems is that it has a faster reaction time.

It's important to correctly identify the problems that you're having, and provide the correct solution to it. If you really need an upgraded alternator, no size of capacitor will help. And if you really need a stiffening capacitor, no amount of extra alternator capacity will help, although a better voltage regulator and battery might.

I had an upgraded alternator, but now I'm running a stocker again, because it's good enough. If I keep my system cranked up all the time, it will drain the battery, but since I never really do that, the stock alternator is adequate. I have a .5F capacitor because I need it. Even with the upgraded alternator, (and voltage regulator) I still needed the cap.

I'm a firm believer in the correct solution for the problem.

[Miles]

Originally posted by SupraKid
"Lights dimming" when the bass notes hit is a different problem, and is caused by the battery and alternator not keeping up to the transient demands of the system. For this kind of problem, a capacitor will do an excellent job of helping the problem by evening out the system demands. Increasing alternator output has little or no effect on this problem.


elementary physics disagrees with you. lights dim because of an amp drawing more current than your electrical system can provide at a given moment. if your alternator puts out higher current, then you won't have that problem.

EDIT: just look at any db drag type competition vehicle. most of those cars have power demands that would cluster fuck your little stock alternator and cap. the vast majority (if not all) run without caps and do just fine.

[aaron1017]

My offer still stands..... :wave:

[Bumpin Expo]

I think im just going to stick with no cap. And sorry MDIFY, i didnt mean to call u a dick, u arent either aaron...or saggleman...who else is left in this forum?

[MDIFYTD]

Don't worry about it I was just joshin ya.

[aaron1017]

Damnit, I was looking forward to that subway too....

[Kirk]

Originally posted by saggleman
elementary physics disagrees with you. lights dim because of an amp drawing more current than your electrical system can provide at a given moment. if your alternator puts out higher current, then you won't have that problem.

Not trying to start a pissing contest whatsoever or an arguement, just a conversation here. I am speaking from experience.. adding a bigger alternator on my car did not help the lights dimming whatsoever - I still have to upgrade the battery wires so there may be my problem right there - haven't had time to get around to it; busy.

As to Afboy, find out what problem you may have if any with lights dimming, etc.. before you consider going with a cap. If your system is going to be big and you are serious about it, go about it the right way by upgrading the wires as well. Thats something I skimped on at the beginning and it was my own fault.

[TBSpyder]

You're right SupraKid...a system is only as good as it's weakest link. But from my experience, too small of an alternator is the problem on most econo cars. I would fully agree though that if another area, such as your battery or wiring is also insufficient, then you're going to see little improvement.

When running, though, vehicles draw more current from the alternator than the battery.

[Bumpin Expo]

i was accually looking to upgrade my battery cables to 4 or 0 guage cuz i saw that on another forum. I have two posative wires going to my batt and two neg batt wires and the guys said to jus not do it cuz i could really fux somethin up

[Kirk]

2 positives for what? they go to seperate parts for your system? Just use a dist. block.

You can have 2 grounds off of the battery, that wouldn't hurt. I am actually going to have another ground other than the seperate location under the hood when I upgrade the wires this weekend.

[93ex]

Originally posted by Afboy143
i was accually looking to upgrade my battery cables to 4 or 0 guage cuz i saw that on another forum. I have two posative wires going to my batt and two neg batt wires and the guys said to jus not do it cuz i could really fux somethin up

you sure you didnt see it here ;)

http://www.tamparacing.com/forums/showthread.php?s=&threadid=114195

Altho I need ot improve my ground, I used to run 0 in the civic, and might upgrade to dual 4 fromthe alt, since I hate using ring terminals...

[Bumpin Expo]

nah i read it on caraudio.com forums which i post on sometimes, more on here tho . But thanks for those pics, looks interesting. And when i mean 2 wires goig to my negative like one wire goes to the posative to the bat to the alt, and the other posative goes from the bat to inside the car somewhere? and the negative grounds in two diff places? o well f it i dont wanna upgrade that jus yet

[93ex]

Well you replied in that thread but whatever

[Bumpin Expo]

do u kno what i mean by two wires going to the pos on the batt and two wires goin neg? Maybe i should take pics

[aaron1017]

Yeah, pics would help.