posted
ok technically i want to know what different would this make? i mean puting a 25 Farad Capacitor in a system with about 3000 watts rms power, an alternator with about 110 amps and a lightning audio battery (the SBATTEX1 extreme duty deep cycle)? also technically is a 25 farad equal to 25 one Farad caps????? is a 25 or 40 Farad anything special for daily drive?
posted
i think 25F is way over excessive. if you actually wanted that much capacitance then your best bet is to use many smaller capacitors (like the 25 1F caps you mentioned). The reason for this is because there is resistance in the output of the capacitor, and having 25 1F capacitors in parallel will effectivly have 1/25th the output resistance assuming all else was equal (which it wouldn't be). Richard Clark was the one who pioneered the idea of using caps in a car's electrical system -- the thing is, he used many many many small capacitors (I'm guessing around 5000uF in size each, but I could be way off) which yielded a very low output resistance. That is the absolute best way of doing it but it would cost much more.
Posts: 30 | From: Canada | Registered: Mar 2002
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posted
thanx substrate. that was really helpfull. but practically i can't buy 25 caps. even if they were cheaper, putting them in a honda civic 2 door HB would be impossible! my question is this though: is a 25 farad cap more like a battery? well it saves alot of electricity and the sound system could use that while the cap is being charged!!!
posted
The a 25F cap will most likely hurt your systems performance. The amps will be competing with the cap for the power. When Alumapro came out with their huge cap I saw several systems where the amps would shut off do to the voltage drop. They all had stock charging systems. 14.4V at the battery, 14.4V coming into the cap, 10.2V after the cap. Skip the 25F cap and get a decent alternator. The stock Honda alts suck. I put a 240 amp Ohio Gen. alt in my 95 civic and didn't use a cap w/4000 watts with no probs.
Posts: 59 | From: Onalaska, Wisconsin, USA | Registered: Jan 2000
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posted
thanx DC. i'll try to do that if possible. i think we couldn't fit that in my civic (92 2 door HB) but i'll see into that. actually i asked this to know more about caps thanx for replies. any one else has any other idea? wouldn't a 25 Farad cap hold enough eneregy to always supply the amps with power? so while the amp is being fed by the cap, the cap is being charged by the battery ... is this right or am i wrong??
quote: so while the amp is being fed by the cap, the cap is being charged by the battery ... is this right or am i wrong??
Yes, you are right.
quote:wouldn't a 25 Farad cap hold enough eneregy to always supply the amps with power?
no, the cap will not maintain a full charge always(depending on the demand from the amp). Think of a cap charging like a garden hose filling a 5-gallon bucket with water and discharging like dumping the full bucket. While it is recharging it will draw power to from the battery and tend send less to the amp until it recovers. Having an upgraded charging system will significantly reduce if not eliminate this lag.
[ 07-16-2004, 12:50 PM: Message edited by: DC ]
Posts: 59 | From: Onalaska, Wisconsin, USA | Registered: Jan 2000
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posted
thanx DC. well what if i get a good alt and then use a 25 Farad cap...? would that make much different? also could some one please explain to me in more detail how using 25 1Farad cap is different than 1 25Farad cap???
posted
The way a capacitor is actually made, is they take two pieces of foil, and a single piece of dielectric (an insulating material) and make a sandwich out of them. So, going from the top down you have one piece of foil, one piece of dielectric, then another piece of foil. One of these pieces of foil is attached to the (+) terminal, and the other piece of foil is attached to the (-) terminal of the capacitor. If you measure the resistance between the (+) and (-) terminals you'd find it to be an open circuit (no connection).
So, we have two "plates" seperated by a dielectric, and when you put a positive voltage on the (+) terminal, and ground the (-) terminal, what happens is that a bunch of electrons get sucked up through ground and all gather on the one piece of foil that is attached to the (-) terminal. They all gather there because the other peice of foil is attached to the (+) terminal, and negative always gets attracted to positive.
The measured capacitance of our capacitor is directly dependant on the surface area between the two pieces of foil and the distance between them. So, if you want a large capacitor you need a LOT of surface area (seperated by the dielectric). To achieve this, they take two very long pieces of foil (and the dielectric material) and roll them up into a tube and stick them into the metal casing of the capacitor. If you were to cut a capacitor open you'd see its a bunch of rolled up foil.
Now, the foil itself is a metal and has resistance. If you think about it, you'd want to have the LEAST amount of resistance as possible so that you could "suck" those electrons out of the capacitor as fast as you can (the flow of current). With a lot of resistance, you can't pull the current out as quickly. So, on capacitors you'll see an ESR rating which stands for "Equivalnet Series Resistance". Again, the ESR is created because the peices of foil have a finite resistance, as well as the connection between the foil and the terminals, as well as the terminals themselves (they are made out of metal!).
Ok ok ok ... so you're getting bored. Here is why 25 1F caps is better than 1 25F cap.
We all know that when you put resistors in parallel you get 1/2 of the resistance. Example: Two 4 ohm resistors in parallel makes a 2 ohm resistor.
So, for all intents and purposes, let's say that the ESR of both caps is 0.015 ohms. In the real world, the ESR of the larger cap will be higher (because there is more foil = more resistance). So, if we simply used the 1 25F capacitor, our amplifier would see a source resistance of 0.015 ohms if it were to draw its power from the capacitor only. Instead, if we had 25 1F capacitors all in parallel, the amplifier would see a source resistance of 0.015/25 = 0.0006 ohms (much smaller!). Again, this is because resitors in parallel make it seem like the overall resistance is less. Moreover, because we have less source resistance, we are better able to "suck" the current from the source (ie. the capacitor).
So, fundamentally, it all has to do with the effective source resistance that the amplifier sees.
Posts: 30 | From: Canada | Registered: Mar 2002
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posted
thanx substrate that was really helpfull. and shadow, there is only one person that can clearify that and that'd be Wayne himself any wayz this was helpfull thanx guyz
posted
Pioneer_Phan: The explanations you were given make several assumptions about the 25 Farad capacitor you speak of. All of these assumptions are incorrect. Both the 25F and 40F LA (and RF) caps use numerous smaller capacitors which are seriesed (increase voltage capability) and paralleled (increase capacitance). They have EXTREMELY low ESR and have proven again and again to work wonders in import vehicles with anemic charging systems. These capacitors are nothing like those of any other manufacturer.
Posts: 144 | From: Phoenix, AZ | Registered: Oct 1999
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posted
Many of us here at Rockford use these in our own vehicles with excellent results. My personal car, a 2k3 Mustang GT, has (1) 1501bd, (1) 1051s, (1) 551x, stock charging system with our RF / Exide battery and one of the 100F Super Caps. Voltage is ROCK SOLID and typically above 13 volts when driving around jamming on anything. We've done testing with these capacitors using an Audio Precision analyzer and found the results to be nothing short of incredible.
Posts: 144 | From: Phoenix, AZ | Registered: Oct 1999
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posted
Capacitors have been repeatedly proven to be effective in enhancing the vehicle's electrical system for playing music -- which is dynamic in nature. The same cannot be said for SPL, in fact the opposite is often true.
Posts: 144 | From: Phoenix, AZ | Registered: Oct 1999
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posted
the non dynamic nature of Sine waves, can not be improved by milisecon discharge of a Cap even if it is a huge cap! this is what i came up with after studying 1000 pages of Cap technical documentation.
posted
so a cap in series with another cap increase voltage capability? would that even be useful if they were 1 farad?
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posted
Putting a cap in series with another cap increases the voltage capability, and cuts the capacitance in two. IE two 1F, 20V caps in series would effectively look like a single 1/2F cap with a 40V capacity. Plus additional ESR, I believe. In car audio, you're not going to have much use for a cap with a 40V rating.
Ash
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posted
caps do work i will agree... i have a brahma 12 at 1 ohm of a ti1200.1 and a 15f cap, with music, even rap with heavy bass voltage doesnt drop below 14 volts... stock alt.... test tones.. down to 11v in no time.....
Posts: 19 | From: Canada | Registered: May 2003
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posted
yes capcitance formulas are the reverse of resistance ones...
Parallel for resistance is reciprical of the reciprical and capacitance is additional
whereas series would be additional for resistance and reciprocal of the reciprical for capacitance
So 2 1F caps in parallel would be 2F but in series they would be 500mf
pardon my spelling ...thats going back 20 years to my basic electronics class, I'm proud of myself Posts: 8 | From: Atlanta | Registered: Aug 2004
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quote:Originally posted by DD Shreder: I'd like someone post SPL increase results with a cap.
ya they dont do much for SPL no one said it did.....but for DYNAMIC sounds like music it can help stabalize your electrical system. I dont use my system for one quick sound and im done for the day. I listen to mine every time im in my truck and even with dual alts i had blinking (due to the ups and downs in power supply/demand) The caps all but stopped any blinking i had. I dont think i ever gained any SPL from these caps but for someone who USES his system for what systems are intended for, like music - it can help.
IMO caps start hurting you ONLY when you dont have enough Alt to supply your system to begin with.
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