Do I need a Capacitor?
Do I need a Capacitor? I have two amps; a Kenwood that puts out 500wrms and a Z Edition(it was a gift) for mids/highs that supposedly puts out 800w peak. Whenever I turn the subwoofer lever more that half way up, or the volume more than 3/4 up with the SWL all the way down the lights dim tremendously. I haven't finished my system yet as far as mid/highs are concerned so I cant go out and buy a new battery, alternator, and 0 gauge wiring right away. I wanted to know what I should do in the meantime to save my electrical system.
This one will sure start a discussion since there are people on 2 sides of this argument: Some say don't, some say it's a must.
I say sort of both. It's necessary to have something in-line to act as a buffer for power surges. Most of the regular 1-2 farad caps aren't really going to cut it with too much power.
What I've eventually migrated too is a product that is more like a battery, but has the quick discharge rate closer to that of a Capacitor. It's called a Bat-Cap. You can find them for sale on E-bay and there website (can't remember it off hand)
You'll pay about the same price, but for a better suited product. Alot of SPL guy's use them. BUT do remember, that you'll eventually get to a point where you must upgrade the charging system. Maximizing the efficiency of the charging system in place helps some. Stuff like a properly sized power wire and the "Big 3" help. (Mike I know you will say something on that....LOL)
I say sort of both. It's necessary to have something in-line to act as a buffer for power surges. Most of the regular 1-2 farad caps aren't really going to cut it with too much power.
What I've eventually migrated too is a product that is more like a battery, but has the quick discharge rate closer to that of a Capacitor. It's called a Bat-Cap. You can find them for sale on E-bay and there website (can't remember it off hand)
You'll pay about the same price, but for a better suited product. Alot of SPL guy's use them. BUT do remember, that you'll eventually get to a point where you must upgrade the charging system. Maximizing the efficiency of the charging system in place helps some. Stuff like a properly sized power wire and the "Big 3" help. (Mike I know you will say something on that....LOL)
Teching In
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Like Richie said there are with out a doubt people who will argue both sides. In my opinion, capcitors are over-rated. Unless you plan on having a competition system which needs to be able to hit SUPER hard at one particular moment then you DO NOT need a capacitor. Your best bet is installing an extra battery in the rear and powering your amps off of that. I know you said that is not an option right now but in my opinion the money spent on a capacitor (although it may remedee the problem right now) will be a waste of money once you do get a new battery. You will have very little use for a capacitor.
That's why I'm a fan of Bat-cap. Quick Discharge rates from a Battery-like design. The problem with large caps in competition is that once it discharges, it has to recharge. That in itself causes a large drain on the charging system.
I was steered towards Bat-caps after watching a demonstration of a capacitor vs a bat-cap with both a short and long burb. The voltage doesn't recover as fast with a cap, but recovers alot better with a Bat-cap in the short burb. BUT with a longer note, there is no comparison what-so-ever. The voltage continues to drop since a cap wanting to recharge that much current at once starts to become like a resistor. The Bat-cap held steady with less drop over-all.
You know....I wonder if a GP on these wouldn't be a bad idea? People will still get caps against some of our better judgments, why not stear them towards a better product if the price is close to what a cap does cost.
I was steered towards Bat-caps after watching a demonstration of a capacitor vs a bat-cap with both a short and long burb. The voltage doesn't recover as fast with a cap, but recovers alot better with a Bat-cap in the short burb. BUT with a longer note, there is no comparison what-so-ever. The voltage continues to drop since a cap wanting to recharge that much current at once starts to become like a resistor. The Bat-cap held steady with less drop over-all.
You know....I wonder if a GP on these wouldn't be a bad idea? People will still get caps against some of our better judgments, why not stear them towards a better product if the price is close to what a cap does cost.
In addition to a cap or two, the best thing you can do is to put in a bigger alternator. Move up to a 200 amp alternator and you can turn up the volume and blow your eardrums out! No more light dimming either.
I think something is up. I have had several amp combinations in my Z (and my Formula before that) up to about 80 amps of amplifier pull. This using legit hardware like Apline, RF, and Memphis, and also using proper wiring straight to the battery and a solid chassis ground.
I might be wrong but I am thinking your total charging draw should be no more than that or perhaps alot less.
So, I would be inclined to say look into your wiring integrity, or perhaps a weak alternator or battery.
I might be wrong but I am thinking your total charging draw should be no more than that or perhaps alot less.
So, I would be inclined to say look into your wiring integrity, or perhaps a weak alternator or battery.
i had a slight problem with this too. it was only at a peak in the bass where it was EXTREMELY loud. my headlights and LED gauges would dim VERY slightly. i put a 1 farad capacitor in and this corrected the problem. all it is doing is providing that little bit of oopmh needed for the sound. but you shouldnt need it all the time. if you do, you are prob already deaf and just need the music up waaay to loud. 
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If you are pushing over 500 watts continuous, and don't have a cap, youre leaving everything on the table.
A car battery is good for about 500-700 watts.
Ive seen people have 2000-3000 watt systems with no cap and it sounded decent when tuned, but with a Cap, completely different system.
sounded twice as powerful.
Ive had 4 setups.
3 JL 10's
2 Rockford HX2 12's
2 JBL 12's
3 Aubiobahn 10's.
The setup with the cap sounded much cleaner, and way louder.
I actually had to tune it down some.
If you don't got a cap, you aint packin.
A car battery is good for about 500-700 watts.
Ive seen people have 2000-3000 watt systems with no cap and it sounded decent when tuned, but with a Cap, completely different system.
sounded twice as powerful.
Ive had 4 setups.
3 JL 10's
2 Rockford HX2 12's
2 JBL 12's
3 Aubiobahn 10's.
The setup with the cap sounded much cleaner, and way louder.
I actually had to tune it down some.
If you don't got a cap, you aint packin.
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TECH Regular
Joined: May 2005
Posts: 470
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I was going to post a new thread but found this one. I have the following:
Kenwood 40x2 RMS for the front component speakers
Kenwood 200x1 RMS @ 4 ohms (currently running 400x1 RMS @ 2 ohms on my JL Audio 12w3v2 DVC sub in a sealed enclosure)
My car came with a 140amp alternator from the factory, and I have a .5 farad cap which I installed 5 years ago. I was always under the impression that the sub amp should have enough power in reserve when other accessories are on and to prevent the lights from dimming out (which it did help a little, and the bass seemed cleaner too). But now, it seems that many are saying they are not necessary.
So, my question is, do I really need a capacitor?
Kenwood 40x2 RMS for the front component speakers
Kenwood 200x1 RMS @ 4 ohms (currently running 400x1 RMS @ 2 ohms on my JL Audio 12w3v2 DVC sub in a sealed enclosure)
My car came with a 140amp alternator from the factory, and I have a .5 farad cap which I installed 5 years ago. I was always under the impression that the sub amp should have enough power in reserve when other accessories are on and to prevent the lights from dimming out (which it did help a little, and the bass seemed cleaner too). But now, it seems that many are saying they are not necessary.
So, my question is, do I really need a capacitor?
Last edited by Jeff 97 Formula; Apr 15, 2007 at 05:32 PM. Reason: Specifying sub in a sealed enclosure
i just installed my system yesterday too and i think im getting a battery tm and a cap. when it hits lights go out on dash at night and my volt meter goes down to the red then comes back up, if im bassing constant for maybe 20 sec the bass starts cutting out i think because of low volts but not sure the amp says it's pulling 4.7 amps @11.6-12.2 volts when it starts doing its thing it is an alpine MRD-M1000 powering a Pioneer TS-W3002SPL 06' model
Originally Posted by Richiec77
That's why I'm a fan of Bat-cap. Quick Discharge rates from a Battery-like design. The problem with large caps in competition is that once it discharges, it has to recharge. That in itself causes a large drain on the charging system.
I was steered towards Bat-caps after watching a demonstration of a capacitor vs a bat-cap with both a short and long burb. The voltage doesn't recover as fast with a cap, but recovers alot better with a Bat-cap in the short burb. BUT with a longer note, there is no comparison what-so-ever. The voltage continues to drop since a cap wanting to recharge that much current at once starts to become like a resistor. The Bat-cap held steady with less drop over-all.
You know....I wonder if a GP on these wouldn't be a bad idea? People will still get caps against some of our better judgments, why not stear them towards a better product if the price is close to what a cap does cost.
I was steered towards Bat-caps after watching a demonstration of a capacitor vs a bat-cap with both a short and long burb. The voltage doesn't recover as fast with a cap, but recovers alot better with a Bat-cap in the short burb. BUT with a longer note, there is no comparison what-so-ever. The voltage continues to drop since a cap wanting to recharge that much current at once starts to become like a resistor. The Bat-cap held steady with less drop over-all.
You know....I wonder if a GP on these wouldn't be a bad idea? People will still get caps against some of our better judgments, why not stear them towards a better product if the price is close to what a cap does cost.
We've brought this up of batcaps.
The XSTATIC BATCAP© is simply a battery that can discharge just a s quickly as a capacitor.
Simply put, it's a deep cycle battery. Honestly, it follows all the properties of a deep cycle battery, rofl. But they won't tell you that.
Originally Posted by burnzilla
If you are pushing over 500 watts continuous, and don't have a cap, youre leaving everything on the table.
A car battery is good for about 500-700 watts.
Ive seen people have 2000-3000 watt systems with no cap and it sounded decent when tuned, but with a Cap, completely different system.
sounded twice as powerful.
Ive had 4 setups.
3 JL 10's
2 Rockford HX2 12's
2 JBL 12's
3 Aubiobahn 10's.
The setup with the cap sounded much cleaner, and way louder.
I actually had to tune it down some.
If you don't got a cap, you aint packin.
A car battery is good for about 500-700 watts.
Ive seen people have 2000-3000 watt systems with no cap and it sounded decent when tuned, but with a Cap, completely different system.
sounded twice as powerful.
Ive had 4 setups.
3 JL 10's
2 Rockford HX2 12's
2 JBL 12's
3 Aubiobahn 10's.
The setup with the cap sounded much cleaner, and way louder.
I actually had to tune it down some.
If you don't got a cap, you aint packin.
TECH Regular
Joined: May 2005
Posts: 470
Likes: 4
I took my cap out only to find out that the headlights were not dimming any worse without the cap (the only time the lights dimmed and the voltmeter goes down is when the car is at idle, and all the lights are on, only slightly better with the cap). The volts don't go down at all when the headlights are off (with or without cap).
My alternator is the stock 140 amp, and as long as I'm doing better than 1000 rpm, the headlights don't dim, and the voltmeter doesn't move (this is without the cap too). What needs to happen in order for this to not happen at idle?
My alternator is the stock 140 amp, and as long as I'm doing better than 1000 rpm, the headlights don't dim, and the voltmeter doesn't move (this is without the cap too). What needs to happen in order for this to not happen at idle?
TECH Regular
Joined: May 2005
Posts: 470
Likes: 4
So, I guess the stock 140 amp is not big enough for a 400x1 watt rms amp (at 2 ohms)? Should I put my capacitor back in instead? Or is that not going to help since the only time I experience issues is when idling AND the all the lights on?
It should be enough for 400 watts, but it depends on how many other things you have going on. The stereo isn't the only thing that is drawing current from the battery 
An efficient 400 watt amp should only draw about 30 amps which the stock alternator should be able to keep up with fairly easily.
I'd just leave it alone unless it bothers you that much. The cap won't fix it.
An efficient 400 watt amp should only draw about 30 amps which the stock alternator should be able to keep up with fairly easily.
I'd just leave it alone unless it bothers you that much. The cap won't fix it.
TECH Regular
Joined: May 2005
Posts: 470
Likes: 4
Currently using 8ga wire. Yes, I'm aware that there are many other things that are drawing current in the electrical system (since the volt meter stays put when the lights are not on). And yes, when I'm idling the volts drop when the lights are on and a bunch of other stuff (AC, rear defogger, etc), and I haven't turned up the stereo yet. And like I said before, the issues go away when the RPM's are 1000 or higher.
Also, how do I know if I have the 140amp alternator on my LT1?
Also, how do I know if I have the 140amp alternator on my LT1?