capacitor

How do you know if a capacitor isn't doing it's intended job???

Here's my dilema.  I hooked up a 1.2 farad cap thinking it would help me with my light dimming problem and it has not.  The amp I am running is a Phoenix Gold Xenon 600.1 (rated at 612 watts rms @ 1,2 or 4 ohms), the amp is currently running a 2 ohm load.  Anyway, I have seen no change in the lights dimming when the bass drops.

Before you ask, yes, I have checked and rechecked my ground points and they are all very tight.  I ground the paint away to make sure the connection is to bare metal.  No connection point is loose and I'm using 4 gauge wiring from the battery, to the cap and from the cap to the amp.  The ground wire is matching 4 gauge with the cap and amp ground seperately to the chassis.  I have noticed when the stereo is playing at low levels, the voltage displays between 13.6 and 14.2 (depending on volume).  As I crank it up, bass drops take the charge down to about 12.3, but the charge goes back up to the mid-13's until the next drop.  Is all this normal???

Capacitors do not work.  Following is a suggested wiring diagram for a capacitor.

You're hyundai has a tiny alternator.  First thing is to change out the battery and possibly hook up a second at the amp.  Capacitors are kinda like a band-aid in systems with "electrical" problems.  They have their use if they are installed in the correct system.  Not saying your's is wrong, but IMHO you're electrical system in the Hyundai is inadequate.

megaman wrote:

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You're hyundai has a tiny alternator.  First thing is to change out the battery and possibly hook up a second at the amp.  Capacitors are kinda like a band-aid in systems with "electrical" problems.  They have their use if they are installed in the correct system.  Not saying your's is wrong, but IMHO you're electrical system in the Hyundai is inadequate.

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... and adding a battery won't help eithr.  Upgrade the alternator.

i am an idiot wrote:

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Capacitors do not work.  Following is a suggested wiring diagram for a capacitor.

    

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If you liked that one, you are going to love this one.  I even named it HaemCap.

Okay...so capacitors don't work (according to some) and then some say they do.  If it's intended purpose is to store electricity for the amp(s) to draw on when the demand is needed (as opposed to drawing directly from the battery) why don't they work???  If they don't work, then why would so many installers install them in systems that push 500 watts or greater???  This is quite confusing.  You're saying my alternator is too small, but why would they install one that supposedly handles the power needs of the car, but then also have 4...yes, count them...4 12 volt plugs that can be used at any given time for whatever purpose.  I would think that knowing there could be extra draw on the electrical system...the alternator would be a little stronger than the car's basic needs.

I am one to appreciate humor, but so far...nobody has answered my questions.  You've simply stated your strong opinions without much of an explanation, which doesn't help me understand one way or the other.  I'm not a car audio novice, nor am I the grand wizard...I am simply trying to learn and understand so that my system can be the best it can be.

Thank you.

1.  Capacitors do, of course, "work."  They do exactly what any capacitor does in an electrical system, they resist changes in voltage.  They are part of every amplifier power supply to help stabilize rail voltage.  The point of the sarcasm is that they ONLY work as intended (to help an amplifier sustain peak outputs during short transients) they do NOT improve the capacity of your electrical system.  Indeed, if the alternator is already operating near its capacity, a cap will only make matters worse, not better.

2.  Many installers use them for their intended purposes, but far more install them because they look cool, or because they do not understand how they work and have bought into the marketing hype, or because people expect them, or because they can charge a lot of money from unsuspecting customers for them.

3.  You need a high-output alternator.  Period.  Most cars do when a large car audio amplifier is installed.

That should answer your questions - exactly as was already done.

Considering I don't know anyone from adam in this forum, I don't know if the sarcasm is to be taken seriously or as a joke or what.  What I got from the sarcasm was that capacitors don't work (then someone posted that they do).  I also got that my alternator is probably not strong enough.  However, it didn't give me the why's.  You gave a much better explanation that is pretty much black and white...literally.  The only question I have based on your posting is, how does a capacitor make matters worse IF the alternator is operating near it's capacity?

allmet33 wrote:

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Considering I don't know anyone from adam in this forum,

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Click on people's profiles for more information.

allmet33 wrote:

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The only question I have based on your posting is, how does a capacitor make matters worse IF the alternator is operating near it's capacity?

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A capacitor must be recharged and only the alternator can do that.  If the system demands are already causing alternator voltage to droop, once the cap discharges (which takes a second or two) it becomes just another load on the system, helping further overload the alternator.  The first step in any system design is to audit the alternator loading: what does the vehicle require and what size is the alt.  This gives you an idea of how much excess capacity you can use up with an audio system.  In a Hyundai, that is probably less than 20 amps.  Then figure out how much demand your audio system is likely to add to the system and upgrade the alt (and the big 3) appropriately.  I almost never recommend using caps in daily drivers, and then only for specific problems like noise.  The fallacy is believing they will help solve an electrical overload situation.  They are useless for that purpose.

Okay...with the first part, you missed the point.  I haven't had enough interaction with the posters to know their style and how to take them, feel me?

Thank you VERY much for that information.  I completely understand what your'e saying and I appreciate the straight-forwardness of your posting.  The way it was explained to me before was....the capacitor stores electricity for the amp when needed, so it's not a constant draw on the battery, therefore...allowing less of a draw on the battery which means it's easier for the alternator to keep the battery charged.  So basically, if I had a strong enough amp and I hooked it directly to the battery with no cap, and I pumped it loud and long enough...I could essentially drain the battery before the alternator had a chance to recharge the battery. 

Does that make any sense to you?

audiocableguy wrote:

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You're saying my alternator is too small, but why would they install one that supposedly handles the power needs of the car, but then also have 4...yes, count them...4 12 volt plugs that can be used at any given time for whatever purpose.

Those x4 12 volt Acc outlets are designed for charging cell phones, radar detectors, Ipods, etc. Most are fused at 15 amps and will sometimes share circuits with other devises and or be linked between those same Acc outlets.

Cars are being designed for the highest MPG. This is done by reducing weight and eliminating anything not needed. According to the maker, the vehicle has everything you need to drive off the lot. Your desire to add high amperage gear doesn't fit into the plan, the one shared with the million units off the same assembly line. Many trucks must be order with trailering or HD packages to get a higher amperage alternator, larger radiator, trans cooler etc.

"Okay...so capacitors don't work... If it's intended purpose is to store electricity for the amp(s) to draw on when the demand is needed (as opposed to drawing directly from the battery) why don't they work???".

Alternator-Battery-Cap-Load. If the load draws more than the Alt can handle, the energy is taken from the battery. The drop is covered by the cap. Very short term. That used energy must now be replaced. The only way is from the Alt. If you have too small an Alt. The sag is too long for the cap do do anything so it become load. The Stiffening Cap can't do anything but store energy. Same voltage in-Same voltage out. The scientific factors are covered in other posts. A second battery can cause the same issues. You must make energy first than decide if and when it needs to be stored. This is a very simplistic attempt to explain.

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Understood...and thank you.

DYjohn is right again, as I keep noticing on this board.  I think the common misconception on Caps out in the world is that the cap is 'isolated' from the electrical system as far as power strain is concerned.  As D was explaining, the cap needs to recharge after the amp 'sucks it dry', and thus draws the current from the system to 'fill it back up' 

As far as the newer vehicles coming with 50 different power plugs throughout the car, the idea is that they would most likely be used for cell phone chargers and the like, which draw very little current.  Even the power plugs in the back of vehicles, like some of the Ford SUV's, are intended to be used while the vehicle is parked and not running.  So in this scenario, the alternator doesn't even come into play.  This is where the smaller alternators are being used more and more in passenger vehicles, and smaller SUV's.

I get customers all the time that don't understand how much a 1000watt system taxes the stock electrical system.  They want their cake and eat it too.

allmet33 wrote:

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The way it was explained to me before was....the capacitor stores electricity for the amp when needed, so it's not a constant draw on the battery, therefore...allowing less of a draw on the battery which means it's easier for the alternator to keep the battery charged.  So basically, if I had a strong enough amp and I hooked it directly to the battery with no cap, and I pumped it loud and long enough...I could essentially drain the battery before the alternator had a chance to recharge the battery. 

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Which would be wrong.  Whoever told you this does not understand how capacitors work... and probably has a number of other misconceptions as well.

megaman wrote:

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DYohn is right again, as I keep noticing on this board. 

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Thanks.  I just realized I've been doing this kind of stuff for a living for 35 years.  This month, in fact...

megaman wrote:

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I get customers all the time that don't understand how much a 1000watt system taxes the stock electrical system.  They want their cake and eat it too.

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This is what I'm starting to understand.  This had never been an issue for me because my previous systems all fell under 500 watts and never gave me any issues as far as lights dimming or anything.  The current amp I have now is pushing at least 600 watts and an installer here in my area suggested installing the cap...so I did.  However, still having the issue with the lights dimming had me turn to this forum where I've received a lot of great advice in the past.

I've been really good a putting together good quality average power systems, but I'm getting started with systems that are a bit stronger and now I'm understanding that one must take into account how that system will affect the vehicle in terms of draw on the electrical system.  I've learned a lot, but I'm not ashamed to say I have a lot to learn as well.

DYohn] wrote:

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p>

allmet33 wrote:

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The way it was explained to me before was....the capacitor stores electricity for the amp when needed, so it's not a constant draw on the battery, therefore...allowing less of a draw on the battery which means it's easier for the alternator to keep the battery charged.  So basically, if I had a strong enough amp and I hooked it directly to the battery with no cap, and I pumped it loud and long enough...I could essentially drain the battery before the alternator had a chance to recharge the battery. 

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Which would be wrong.  Whoever told you this does not understand how capacitors work... and probably has a number of other misconceptions as well.

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Well...it now makes sense as I'm still having the dimming light problem, which caused me to turn here to see if I can get a 2nd opinion...which I did.  Again...thank you very much!

So...can I assume that I really don't even need the capacitor in my system?  I can take it out and everything should run as it does now?

allmet33 wrote:

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So...can I assume that I really don't even need the capacitor in my system?  I can take it out and everything should run as it does now?

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You don't even need a capacitor in your system.  You need to upgrade the big 3 and probably get an HO alternator.

DYohn] wrote:

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p>

allmet33 wrote:

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So...can I assume that I really don't even need the capacitor in my system?  I can take it out and everything should run as it does now?

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You don't even need a capacitor in your system.  You need to upgrade the big 3 and probably get an HO alternator.

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Cool!  I have already begun looking into acquiring a HO alternator...any good suggestions (I'm dealing with a Hyundai here)???

One more question...do I have to worry about draining my battery if I'm cranking my music for long periods, even with the engine running?

allmet33 wrote:

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One more question...do I have to worry about draining my battery if I'm cranking my music for long periods, even with the engine running?

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Sure, if your alternator is severely overloaded, you have to worry about killing your battery, and killing your alternator, and potentially frying other electronics in the vehicle.  How low is the voltage getting?  As voltage drops, current demand increases dramatically to generate the same power (Ohm's Law.)  Current flow generates heat, and eventually something will fry.

DYohn] wrote:

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allmet33 wrote:

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One more question...do I have to worry about draining my battery if I'm cranking my music for long periods, even with the engine running?

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Sure, if your alternator is severely overloaded, you have to worry about killing your battery, and killing your alternator, and potentially frying other electronics in the vehicle.  How low is the voltage getting?  As voltage drops, current demand increases dramatically to generate the same power (Ohm's Law.)  Current flow generates heat, and eventually something will fry.

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I can't tell you how low the voltage drops because I haven't had the system tested.  I can tell you based on my cap with the ditial read out, it goes from about 13.8 down to 12.3 and then back up, but I know that's only the cap, not the electrical system.  It must not be a terrible draw as my lights only dim when I really crank my music and the bass is dropping hard.

DYohn] wrote:

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f the cap is properly installed, it will always be at the same voltage level as the system.  If the lowest it ever gets is 12.3 then that is not dangerous for the rest of the vehicle.  But you should use a real voltmeter and not rely on the cheap indicators attached to some caps.

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That's nice to know, but I will take your advice and get my system checked just to be sure. 

Would it make a difference if I switch to a digital amp (supposed to be less draw)???

haemphyst wrote:

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It will be less draw, but still a significant draw for a stock electrical system. 1000 watts will still be at least 1000 watts in, it's just that a digital amp is more efficient at transferring those thousand watts to the speaker... Meaning it wastes less energy in the LV/HC to HV/LC conversion. I use .50 (50%) for Class A/B amps, and .85 (85%) for Class D amps.

1000/.5 = 2000 watts in for an A/B amp
2000 watts divided by 14.4 = 138A

1000/.85 = 1200 watts in for a D amp
1200 watts divided by 14.4 = 84A

You can see that even class D amplifiers will still tax your electrical system

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Understood...and again, thank you for your response.