Capacitor Testing & Dual Cap wiring

First I have a Rockford 1 farad cap that has been sitting in storage for a about three or four years. How do test is to see if it is still any good? Does it have to be recharged? If so how do I do it? I no linger have the resistor that came with it and to be honest I am not sure if I did it right the first time. Second, how can I wire that Rockford one (if it actually still works) with another one farad cap? The other cap is a 1 farad Lighting Audio cap the a firend has been using up until recently so I believe it works okay but I will test that one as well just as soon as i learn how to test them :) The two caps will be used for one Rockford 1000bd amp. Thanks in advance....

please read the cap sticky at the top of the page......sounds like you are using caps as band-aids to keep your system running2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR

2007 USACI World Champion

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Adding to what Jeff has suggested, caps don't go bad. If there are no leaks and the can is not swollen, there should be no problems with it. Adding to that, you cant "charge them wrong". They will explode if you try. Connect the negatives of both caps to the ground of the car, and then, touch a telt light lead to the positive power lead (whether at the battery, or at your distribution block, it won't matter) and the tip of the light to the cap positive. The light will come on, and VERY SLOWLY (for 2F, it could take 3 or 4 minutes) fade to out as the cap charges. When the light goes completely out, you can then permanently connect the positive power cable to the positive terminal of the cap. All that being said, if you think you need THAT much cap, you need to fix what's wrong first. First thing you should be looking into is upgrading your alternator, battery, and underhood wiring (called the "Big 3"). You are not helping anything at all by throwing more cap at it...It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

I am not so sure that i need the 2 farads I just figured if I have it why not use it..... I'm am thinking at this point that my charging sytem will handle the load just fine since it is a 140amp alternator which should be more than adequate since I do not intend on maing out the amps power at all times or anything near that. The point for the caps to my understanding is that they help with any potential latency in your charging system when you hit a sudden hard deep note, becaue the cap stores then dissapates the electricity faster than a battery can giving the alternator a chance to kick it into high gear so to speak. If I am way off base then just let me know. I am sure many of us lak a true understanding as to what some of this stuff is actually good for.

trodder wrote: I am not so sure that i need the 2 farads I just figured if I have it why not use it..... I'm am thinking at this point that my charging sytem will handle the load just fine since it is a 140amp alternator which should be more than adequate since I do not intend on maing out the amps power at all times or anything near that. The point for the caps to my understanding is that they help with any potential latency in your charging system when you hit a sudden hard deep note, becaue the cap stores then dissapates the electricity faster than a battery can giving the alternator a chance to kick it into high gear so to speak. If I am way off base then just let me know. I am sure many of us lak a true understanding as to what some of this stuff is actually good for.

I'm glad to see you have not fallen into the "Cap Trap". That is exactly what a cap is "supposed" to do, although I have never seen a manufacturer PROVE that's what they do. As long as you keep in mind that caps are REALLY nothing more than band-aids on an arterial gash, and don't expect more fom them than they are supposed to do, then go for it, they cant usually HURT anything.It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

haemphyst wrote: Adding to what Jeff has suggested, caps don't go bad. If there are no leaks and the can is not swollen, there should be no problems with it. Adding to that, you cant "charge them wrong". They will explode if you try. Connect the negatives of both caps to the ground of the car, and then, touch a telt light lead to the positive power lead (whether at the battery, or at your distribution block, it won't matter) and the tip of the light to the cap positive. The light will come on, and VERY SLOWLY (for 2F, it could take 3 or 4 minutes) fade to out as the cap charges. When the light goes completely out, you can then permanently connect the positive power cable to the positive terminal of the cap.

Does that mean tie the negative terminals together to ground and the positive terminals to B+ or battery? Then obviously a negative lead from caps to negative terminal on amp and positive lead from cap to positive lead on amp? Also I am assuming that I ground the test light as usual and then touch the positive lead to the battery terminal to create a load for charging the cap?

No. Read it again. Cap negatives to the chassis, test light BETWEEN battery positive and cap positive(s).It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Flakman wrote: haemphyst is good at the delicate work as well...not just good at overtightening power tools LOL!

Thanks, man... I treat my car stereos like I treat my women. With kid gloves, and a soft touch! It gets more (and certainly more desirable) results than "ham-fisting" 'em into submission...

Flakman wrote: Wondering on the CAP deal...if the cap DOES end up helping with latency from the battery/alternator. Doesn't that just bring you back to the issue of not supplying enough power from the charging system? It would seem to me that if you are running into that issue, your charging system is just marginally good enough and the cap is then "just a bandaid".

Please read this post I commented on early on in my days here at the12volt. Not a bad observation, at all. And this is where all the contoversy comes in, AFAIAC. Your alternator, being a mechanical device will have significantly more lag than would a chemical device - AKA, a battery. It's slew rate will be on the order of tenths of a second, where the battery will be on the order of a few hundredths of a second, and cap can respond, effectively, instantaneously. The speed at which a cap can respond is DIRECTLY governed by 1: the ESR of the cap (equivalent series resistance) and 2: the inductance (L) of the cap. The ESR is determined and affected by the connection scheme inside the cap. If the plates are simply connected at the beginning or end of the rolled up foil, the current has a long way (relatively speaking) to travel, until it reaches the terminals. This travel over the plates is where the resistance comes into play. A high resistance will also affect the charge time of the cap. Higher ESR will mean a longer charge time as well, reducing the filtering capabilities of the device. Most "stiffening caps" are connected at the top of the plates in MANY spots. Each wrap of the foils will have a connection point at the top of it, so all of the surfaces of the plates are connected very close to the terminal. This reduces the ESR of the cap, as the current has a very short distance to travel, basicly the length of the cap. Another benefit to this connection technique, simply by reducing the resistance, the cap will suffer fewer losses to heat. The L (inductance) of the cap is also affected, for different reasons, by the construction techniques employed in the cap. Whenever a current travels in a conductor, it sets up a magnetic field, and inside a cap is no different. When the extremely high current densities inside a cap setup their fields, this drastically reduces the current capabilities of the cap, so the top connection scheme inside a stiffening cap happens to lower the L of the cap as well. Really, all a cap is, in the big scheme of things, (and this is purely conjecture on my part, as I have never done actual tests to confirm my opinions) is a filter, or a current moderating device. From what I understand of electronic devices, a cap will be there for the instantaneous current demands, the alternator does not have to make PEAK current, immediately, or ever, really... This is left to the cap/battery combination. This makes life a bit easier on the alternator, not having to make peak, after peak, after peak. This does NOT mean that you can use a cap as the band-aid as everybody seems to think it is. The alternator will still have to make (on AVERAGE) the same amount of power as the system is producing, so a HO device is still demanded. The alternator will still have to provide high currents, just not a 200A gulp here, then a 50A gulp, then 150A, then 75A, in pulses and peaks. It will just have to provide 100A on a more continuous basis... i.e. CONSTANTLY. This will happen because of the filtering capabilities of the battery/cap combo.It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."