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Old 05-25-2007, 09:38 PM   #1
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Default Cap installation

Hey gang, I got my system up and running. Now the only thing that I am by which perplexed is my cap shows no sign of life. It has a digital voltmeter, and it does not light up at all.

The owners manual said it wouldn't light up until it was fully charged. I've never charged a cap before but I know from other post that it only takes about 6 minutes.

I tried to charge it by installing the resistor in the inline fuse holder, I waited and nuttin'.
the status LED won't even light up.

Hookup is as follows, if any of it is wrong please correct me
4 gauge fused 12" from battery straight to cap
from the cap to one input of the dist. block ( 4 gauge)

I used a multimeter to test the coltage at the terminals of the cap and it read a solid 13 volts.

Maybe the display is just bad??

If y'all got any ideas shoot 'em by me,

Tim
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Old 05-30-2007, 01:00 AM   #2
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Default Re: Cap installation

Quote:
Originally Posted by bonnevillemac
I used a multimeter to test the voltage at the terminals of the cap and it read a solid 13 volts.
Seems to me this means your cap is charged.

Quote:
Originally Posted by bonnevillemac
Maybe the display is just bad??
That'* what I would think...
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Old 05-30-2007, 02:46 AM   #3
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Is there a connector for a remote turn on lead, for the display on the Cap ?

Dutch
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Old 05-31-2007, 07:26 PM   #4
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Dutch, the company I got it from has a model with the remote turn-on, but mine doesn't have it.

I think I will test it again this weekend and make sure it is charged.

Thanks for the help, guys

Tim
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Old 06-02-2007, 11:42 PM   #5
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Dude, if I read you correctly, you wired your cap in series between the + battery pole and a distribution block for the + supplies of your accessories.

That would be the wrong way to wire a cap.

The whole point (in theory) of putting a cap in your system is to prop up the positive supply rail. So you'd wire it with the + cap pole to the + battery pole, and you'd wire the - cap pole to your car'* ground.

While I could go on at some length about why I think a cap should not be necessary, it wouldn't be respectful of your question, which is about how to wire up a cap, so I'll just stick to giving you wiring advice.

Let us know how it works out. Oh, and if you wire a large cap backwards, it will typically explode spectacularly, so don't do that.
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Old 06-03-2007, 12:50 AM   #6
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I assumed that the problem was with the display not with the actual Cap Installation.

Just for clairification sake the Cap has to be wired in Parallel, Not in Series.

The Cap should be wired as follows:
The Main Power wire to + post of the cap, then a second wire from the + post of the Cap to the input side of the Power Distribution Block.
Then a Ground wire from the - post of the Cap to a good ground (this wire should be the same size as the main power wire or bigger).

Dutch
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Old 06-04-2007, 06:41 PM   #7
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I went back and reread my post and I really didn't make it clear how I have it wired.

I have 4 gauge power wire from the positive post on the battery to the + post on the cap. The power wire then goes to a distribution block.

The cap IS grounded to the chassis. I grounded it about 8" from the cap to a point in the trunk that I scraped free of paint.

Sorry for the confusion.

Thanks for the help,

Tim
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Old 06-04-2007, 07:01 PM   #8
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Then your cap install appears to be installed correctly.

Your voltmeter test, did you test it with the cap disconnected from the battery, or while it is still connected? If it was still connected, then you merely read the voltage of the battery. If that was the case, disconnect the cap and measure if it has a charge.

NOTE: If you go to disconnect the cap to see if it is charged, BE FRICKING CAREFUL. If you use say, a metal wrench to disconnect the + pole from the battery, and you accidentally bump the wrench into anything grounded, you'll be shorting both the battery AND the cap, and a fully charged cap in the farad or so range is a powerful thing!!!

Caps are pretty simple electrically, it should charge up pretty quick. I'd say way less than six minutes. Six seconds maybe? If it holds a charge, then yes, I'd say the display on the cap is bad.
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Old 06-05-2007, 04:46 PM   #9
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Quote:
Originally Posted by Bugsi
Then your cap install appears to be installed correctly.

Your voltmeter test, did you test it with the cap disconnected from the battery, or while it is still connected? If it was still connected, then you merely read the voltage of the battery. If that was the case, disconnect the cap and measure if it has a charge.

NOTE: If you go to disconnect the cap to see if it is charged, BE FRICKING CAREFUL. If you use say, a metal wrench to disconnect the + pole from the battery, and you accidentally bump the wrench into anything grounded, you'll be shorting both the battery AND the cap, and a fully charged cap in the farad or so range is a powerful thing!!!

Caps are pretty simple electrically, it should charge up pretty quick. I'd say way less than six minutes. Six seconds maybe? If it holds a charge, then yes, I'd say the display on the cap is bad.
When I go to test it again I'll disconnect the ground terminal from the battery. That should take care of any issues of that nature right??

The first time I tried to charge it I placed the supplied resistor in the fuse holder at the battery.
I had both terminals connected at the battery.
Is this correct or not??

How would you recommend charging it??
I have never done this before so please pardon my ignorance.

Thanks for your help

Tim
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Old 06-05-2007, 08:01 PM   #10
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Yes, disconnecting the battery ground terminal would be an excellent safeguard.

Yes, you can connect a resistor or not, a cap will charge up. Think of it like a bucket of water. If you connect it up to the battery, it will fill up. Think of the resistor as a slightly open valve. It might slow down the charging, but the cap is still going to fill up. (flowing water -vs- electrical current analogies are common, but not exactly equal, but for this example, it is pretty good.)

When the cap is connected to the circuit -via a resistor or not- current will instantly begin flowing through the cap, charging it with ever-increasing voltage, until the voltage on the capacitor matches the voltage of the battery.

In theory, if a circuit (like your amplifier) connected to your battery demanded more current than your battery could supply, current will drain from your capacitor to make up the difference, discharging the voltage on the capacitor. This discharge will continue as long as the current demand lasted, until the capacitor is drained of charge. At that point, the functioning of the circuit (amplifier) will suffer, as current cannot be supplied to meet the demand. The result will be some form of distortion in your audio, as the fully amplified signal cannot be fully amplified. When the demand for current goes away, current will flow back into the capacitor, charging it back up, until a new demand occurs.

In a typical car system, you'd ideally choose your components wisely (battery, alternator, & amplifer) such that you don't demand more current that your car'* electrical system can supply. But I'm pretty sure the use of a capacitor is intended for those very VERY short fractions of seconds when current demand may be very large. The cap is intended to keep the current supplied so your audio quality does not suffer.

What you should REALLY do to get an idea of how it works is put an ANALOG voltmeter across the + and - terminals of your cap. (Be very careful and do not touch the cap poles with your fingers or hands, large caps can be lethal.) But if you can clip meter leads to it, you can actually watch your cap charge up. If your cap is already charged, you can clip an intelligently chosen high-current resistor across the terminals, and observe the voltage on the capacitor fall as it discharges (as heat off the resistor -if you use too small a resistor, it will go up in flames).

You can get an excellent idea how long (or short) it takes for your cap to charge. A digital meter will work too, you'll just watch the numbers run up and down, but a meter with a needle is much more illustrative of what is happening.

I've never used a cap in any car audio system, and people will debate all day long about whether they do any good. But if you're careful and don't get zapped installing it, it certainly won't do any harm to your audio.

Note: A cap will HOLD A CHARGE for a very long time if charged and removed from the circuit. A large cap like those used in car audio can be lethal for days or weeks unless safely discharged. Safe discharge is done by clipping a high-power-handling resistor across the cap terminals. Dangerous discharge is done with a screwdriver with an insulated handle and can melt the tip of the screwdriver.

Disclaimer: Proceed at your own risk, I take no responsibility, blah blah blah.
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