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**Creepy Cruiser** · 01-05-2010, 05:07 PM

It's not about voltage,(it doesn't care what voltage it's running at), it's all about supplying instant amperage to what ever needs it. Think of it as a second battery in parallel, that charges and discharges almost instantly. What are you using it for?

**Morella** · 01-05-2010, 05:27 PM

I want to put it in the aux battery system in the belly of the hearse, so that I have a supply of ripple-free power, with a little kick in case something draws too much current. I think that it should go in the feed wire that goes from the + terminal back to the dash, because it is a feed directly from the batteries. It probably won't help with the original main power system, because it is not connected to the rear batteries, unless you turn the bus tie on for charging, and I don't think that the wire is heavy enough to go back through the bus tie connector, through the cap, and back.

What I'm thinking about is, do I install it in the breaker panel under the dash, which is used for all of the auxiliary system, or put it back in the belly, in the electrical rack? The manual says to put it as close to the load as possible, but this is not being installed for its intended purpose. I am working on installing cooling fans for the electrical stuff back there, where the church truck used to go, so heat shouldn't be a problem. I am just looking for the best place to put it so that it protects all of the accessories. I am working on getting all of the non-critical systems, like A/C, power windows and seats, radios, etc., onto the aux bus, but I've been a little nigardly in this project.

This is probably more information than you need, but, basically, I need to know whether to put it next to the batteries, or under the dash next to the electrical panel.

-denise

**Creepy Cruiser** · 01-05-2010, 10:36 PM

How big is it? (farad wise?)

Car Audio Capacitor Installation

http://www.caraudiobook.com/car_audio_power_capacitors/car_audio_power_capacitor_installation.htm

Car audio capacitor installation. Includes power capacitors and stiffening capacitors.

How do you hook up a 1 farad capacitor to your amp? - Answers

http://wiki.answers.com/Q/How_do_you_hook_up_a_1_farad_capacitor_to_your_amp

A FARAD IS HUGE TO BEGIN WITH connect to amp? what an amplifier, output input?: people answer this question with no idea of what is the question .Answer 1You first have to determine which side of the cap is positive and which side is negative. You run a wire from the negative side to the chassis and for the positive side you run a cable from the battery to the terminal and from the terminal to the amp. so that the two positive wires join together on the positive terminal of the cap. Be careful not to mix up positive and negative on the cap because it could explode and cause damage. Answer 2Because the capacitor is used to filter changes in supply voltage to the amp, the capacitor should be as close to the amp as possible, and connected with heavy wiring. The capacitor also acts as a huge reservoir to supply lots of current as the amp signal hits high levels. By providing plenty of current when it is needed, distortion in the sound is minimized. The key is lots of capacitance, as close to the amp as possible, and thick cables capable of carrying lots of current.Answer 3Be very careful with that thing. The current output of a capacitor is the product of capacitance, in this case 1, and the change in voltage with time. Thus, if you do something to cause a quick change in voltage with that, you will get a very large current spike, possibly hundreds or even thousands of amps. Also note for this reason you should really pre charge capacitors of this size. Let's say you have 1 ought wire run from your battery to the cap, with a resistance of .001 ohms. (I actually have no idea what the resistance of your wire is, I just made that up for argument's sake) When you connect the discharged capacitor, you are causing an instantaneous change in voltage. (IE dv/dt equals infinity) This means that the capacitor will appear to the circuit as a dead short. Thus, the _only_ thing limiting your current flow is the wire. Ohm's law states V equals IR. As the wire is only 0.001 ohms and the system is 12V, this means that when you connect that cap to your car battery it will ["try to"-j3h] draw 12000 amps. I don't think that's good for any part of your system.The solution? Get a resistor and charge the cap through it. The resistor will limit the current flowing into the capacitor until it is fully charged. Then it is safe to connect as the potential between the capacitor and the battery will be 0VDC. A light bulb will work very well for this task, if you don't have any power resistors laying around. This will lengthen the life of both your battery and your capacitor. Also note that if you have a fuse between the battery and the cap, the surge current will blow the fuse without pre charging. If you have a switch or relay in between the cap and the battery, a pre charge circuit must be used as the surge current will weld the contacts closed. (I've seen it)Answer 4Hi -Don't mind me but fortunately a car battery really can't put out 12,000 amps due to the limiting source impedance of the battery- You might get only a thousand amps at best !!!!(using thevian and norton theory)- OK this is still dangerous. OK like a lot dangerous but the internal resistance of the source, the battery its self is also a part of the equation- Dead shorting a battery is bad news- also you might consider the time constant to charge the cap !!! Tc= R times C (five usually required for full charge)Answer 5In each "Time constant" (T) the potential on the capacitor will increase .67 of the remaining way to the battery potential. If the limiting resister is large, this could take minutes, if small then milliseconds. You want a few seconds.Yeah LIKE anybody can go out and buy one. 1 farad is very big to charge that thing, it will take forever if and one volt supplied from a one ohms source and 1 ohm 1 x 1 x 5 = 5 seconds. Now it is almost fully charged. Some people just don't pay attention to what they read I guess. How to connect it to the input a very Good short for a very long time at the output the same resultsAnswer 6First of all I'm going to say all you have to do is make sure that you use thick oxygen free car audio wire. I did a reinstall the other day and someone had used 220v household cable to wire their amp! Who does that? that being said single -aught is going to be efficient enough for all of you 1 farad guys it's easy just make sure pos to pos and neg to neg and for goodness sake charge the thing before you use it. If you read up on this page somebody has already taken the time to explain the ohms law and how to blow up your battery so be careful.Answer if it is a capacitor made for a car amp the have a circuit board on top so they will not instantly charge off the battery they will charge slowly till they are full on their own that's how they were designed.Re; Answer 6. What on earth is "oxygen-free audio wire"? I have assembled a good deal of industrial electrical and electronic equipment over the years, much of it to tight quality-control specifications, and NEVER has that description appeared anywhere. And this is equipment needing better quality than in a hi-fi. Those peddling it have found a nifty way to charge over the odds for... plain, or perhaps tinned, copper wire. Yes, some copper is treated to remove any included oxygen but that is for heavy sheet and profile sections purely for welding, to prevent brittle welds: its electrical properties are not affected. It matters in some parts of an audio circuit that the leads are screened against interference, and the wire should be bright or tinned in connections because surface oxide will degrade the connection and may even introduce odd partial-rectification problems, but the notion that it has to be some magical "oxygen-free audio wire" is a myth and a con.Careful not to exceed the Caps voltage rating. 1 farad caps typically are a low voltage device.

Depending on the size, (if it's about 1 farad) you'll need 4 ga wire running to and from it. Also an inline 200amp fuse or breaker to keep it safe.

Make sure you charge and discharge it correctly. Use the resistor to charge it slowly, and to discharge it you can just hook a test light or tail light bulb to it until it stops lighting up.

***Remember that thing CAN KILL YOU, make sure if it's charged that you DO NOT touch the terminals.*** Also if you short it out, it becomes a very powerful bomb.

**Morella** · 01-06-2010, 01:30 PM

It's a 2.5 farad, maybe more than I need, I don't know. Do you know what wire size and current limiter I need for it?

Thanks,

-denise

**Creepy Cruiser** · 01-06-2010, 04:08 PM

Yep, that's way more than you'll ever need, lol. Most of those we run 1/0 Gauge wire through out the whole system.

**BIGEVIL** · 01-06-2010, 08:04 PM

If the DC voltage of the car electronic system exceeds over +/- 0,1 ampere (I'm quoting here), the capacitor will automatically operate

Thats for the digital display/lights to come on.

**BIGEVIL** · 01-06-2010, 08:06 PM

You can use a light bulb to charge them too.

Also, put it after the fuses.

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