digital capacitor
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=105665
Printed Date: May 23, 2024 at 8:56 AM
Topic: digital capacitor
Posted By: oldschool48
Subject: digital capacitor
Date Posted: June 24, 2008 at 5:58 PM
Hello, I'm helping my son install a sound sytem in his car. The car is a 1984 Porsche 944 4cyl. It has been a unique restoration project. My question pertains to the intallation of the Digital Capacitor it's a Power Acoustik 3.0 Farad PCNC-2.0F. We have 2 Amps. a SP2X 1200 2 channel for the Subwoofers and a Power Acoustik SP4X 600 for the front and rear seat speaker. ... I have never intalled a Digital Capacitor so I wanted to ask before burning damaging the system. The capacitor has 2 entry points for the Positive and 2 entry points for the Negative side. At first I thought it would have been to come in with the power from the battery and out to the Amp. But the manual shows the power from the battery going to a terminal block and back to the capacitor. My question!!! Can i connect both Amps to this capacitor? Like I said this is all new to me. thank you for any help you can give me. ------------- Jorge Bosque
Replies:
Posted By: jar754
Date Posted: June 24, 2008 at 6:22 PM
yes that is what it is for, to wire multiple amps. u say its a 3 farad cap. u figure u need only 1 farad per 1000 watts
Posted By: jar754
Date Posted: June 24, 2008 at 6:36 PM
im not sure but i think that model is a 2 farad cap but your still ok, alot of people dont like caps but personally i think there good for smaller systems, y would these big companys sell them if they didnt have some positive effect in a system, also look into upgrading the big 3
Posted By: jmelton86
Date Posted: June 24, 2008 at 6:38 PM
You'll only really need for the sub amp to be connected to the cap. It's the one that draws huge amount of current. Get a distribution block. Have the power wire from the battery going in, and two going out. The two going out should go to the Power Acoustik and the cap. Have a wire going from the other cap positive terminal to the sub amp. Why is it that you are using a cap, by the way? Do a search on this forum on how people feel about caps. You'll see that the majority of senior members recommend NOT using them. Seriously, do a search. It might save you some trouble in the future. ------------- 2013 Kia Rio -90a alternator
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Posted By: oldschool48
Date Posted: June 24, 2008 at 6:45 PM
Thank you everyone advise well taken Greatly appreciated Thanks Again ------------- Jorge Bosque
Posted By: audiocableguy
Date Posted: June 24, 2008 at 9:28 PM
"y would these big companys sell them if they didnt have some positive effect in a system"
They are an easy sell with a huge markup. Marketing!
Posted By: i am an idiot
Date Posted: June 24, 2008 at 9:51 PM
Hi there, Billy Mays here, I want to talk to you about Mighty Putty, OxyClean, and Capacitors for your Stereo System. Why would these big companies sell them if they did not have a positive effect? Maybe, just Maybe their Bottom Line.
Posted By: jar754
Date Posted: June 24, 2008 at 11:03 PM
first let me point out that i said they are good for SMALL SYSTEMS. they do have a positive affect with eliminating alt whine,engine noise, and headlight dimming. i definitly wouldnt use it when building spl system, however sure its no different than saying that your car needs zmax or duralube but it doesnt hurt to, yeah the affects are minimal but they do have positive affects.i guess what i was trying to say is that they are not selling something thats gonna hurt or damage your sytem (if installed propery).
Posted By: dragon51
Date Posted: June 24, 2008 at 11:40 PM
You really need to look at upgrading the alt. Using the caps can end up hurting your system since you still need to have enought power to keep them charged up. They are sold alot and are hyped up as well, there is only one way to do this right and it's with a bigger alt. I have a old Power 1000.1 fosgate amp that I would love to hook up but I don't have the extra money to get a good alt. I have burned up 3 alt's when I was younger and did not know better. And its not much fun getting stranded in the middle of bfe because your stereo system burned up your alt and now your battery is dead. Even more fun since I was in high school in 1995 ya know when cell phones were not around. But hey it's your kids system just make sure he has a cell phone and is not out of servise. Do yourself a favor and use the search key and type in cap. They do have there use but it take a bigger charging system to take advantage of them.
Posted By: falconyellow
Date Posted: June 25, 2008 at 2:48 AM
Capacitors are a huge hot-button topic and it's largely the industries fault (marketing, bottom line, etc.)
A long time ago some smart guys decided that using a giant capacitor would help filter the input to an amp and help keep the supply voltage at a constant 14.2 volts or whatever their alternator were putting out. Just because an alt can put out a lot of current, doesn't mean it can react quickly enough to keep an amp happy. These smarter guys also learned that you need the capacitor to not only be big, but to also discharge and charge quickly enough so that it can indeed supply the amp with the voltage when it needs it (I.E. cap can't be as slow or slower than the alternator, or what's the point in having it?).
Manufactures noted that this was another object they could create hype about and sell to everyone they could bamboosle into thinking they needed. So people with no knowledge of how they function wrote marketing crap to sell them to other people who have no knowledge of how they function (most customers). Couple that with dishonest or naive sales staff throughout the world and you have a slew of misconception and misapplication propagating ridiculous claims that don't pan out.
Cap facts:
Capacitors can only store and discharge energy. They cannot create energy and due to the laws of entropy, will actually waste some energy in doing what they do. A capacitor must have a very low ESR or it will not do any good and only serve to separate you from your money. Additionally the wiring between the capacitor and your amp should be as short as possible and very low resistance or again, it's going to be pointless. I've seen installs where the cap is in the engine compartment by the battery and the amp is in the trunk and that is essentially pointless.
I don't know of the technology used by these newer 3, 20, and 40 farad caps, but honestly I doubt unless some miracle, alien reverse-engineering type technology I don't know about has replaced conventional electrolytes, that these monster caps will discharge fast enough to do any good. 8 years ago that technology did not exist, I know for fact. Getting big Faraday numbers is easy, getting a cap to charge and discharge quickly at them is not.
Those digital deals on top of the cap? Marketing department! Who honestly cares what the voltage is at that point? If the read out switched at the speed of the actual voltage fluctuation, you wouldn't be able to read it. To keep the readout steady, they use a resistor. Sometimes these devices increase the ESR of the capacitor (typically .002ohms or less in a quality unit) to the point where it does no good (like .25 ohms or more in a cheapie unit). If you're truly buying the cap to use it (rather than for show), the digital read out should be avoided.
Back in the mid nineties I knew a guy who cut apart capacitors and most were only half or 3/4 full of foil (stinger was one of the worst). There are also different types of foil and as already mentioned, electrolyte as well. All this affects the ESR and actual capacitance of the unit. Since the machine necessary to test the capacitance of even a one farad cap will cost thousands of dollars, manufactures know they can sell you about anything and you'll be forced to believe them.
Most failed cap installs are the result of either a bad install (too much resistance between the amp and capacitor) or a "cheap" capacitor (too high an ESR to begin with). In either case the addition of a capacitor will do nothing to help the system. Also, caps should not be relied upon to replace an alternator! If your alt puts out 50 amps and your system draws 60, the cap ain't gonna do you any good!
A capacitor is a supply voltage filter, it will smooth the incoming voltage level at the amp and that's all it can do (if the above criteria are met so that it actually can) do that.
A capacitor will not place a substantial increased load on your alternator because it is not the item drawing it down in the first place. The exception is the mention of entropy above, I don't know how much energy a cap wastes, but if it's a super-low ESR unit (and it had better be) then it can't be enough to hardly measure, more or less worry about.
Too much capacitance won't hurt, but is pointless.
Posted By: oldschool48
Date Posted: June 25, 2008 at 9:16 AM
A lot of info but well taken. The has a 115 amp Alternator and very little when it comes to electrical gadgets in the vehicle. I totally understand the point of view that the capacitor will not be a supplement for the Alternator just a stablelizer in some sence. The 2 Amps that we have are fairly small (1200, 600) and don not draw a heck of a lot of amps. I agree with everyone point that if not connected nor used properly it won't deliver what it's supposed to. Thank you all for the great amount of advise everyone has offered. Thanks Again ------------- Jorge Bosque
Posted By: DYohn
Date Posted: June 25, 2008 at 10:34 AM
... I have been resisting posting that there is no such thing as a "digital capacitor" but I will stop resisting. I assume by this you mean either that is the name brand, or that it has some sort of digital voltage display? A capacitor in a power system will do exactly what any capacitor would do: act as a small capacity voltage storage unit. When used within their capabilities they do exactly what physics says they will do. If they are intended to boost or supplement an inadequate electrical system, they will do more harm than good. As long as the alternator has enough capacity for the system demands, a cap in a system can help smooth out any voltage fluctuations caused by transient demands and will enable an amplifier to maintain peak outputs more consistently. They will not prevent dimming lights or overcome overloads on your alternator. So as long as you are not expecting miracles, they do exactly what they are designed to do. Did you ever get your installation questions answered? If not, try HERE. ------------- Support the12volt.com
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