Capacitors

[ahole-ic]

There's a lot of bs that floats around on this forum about capacitors. The most common misconception is by newbs thinking they magically store huge reserves of power and will fix voltage drop (dimming). Capacitors sit in parallel and do nothing except filter AC. If pure DC is in the circuit the capacitor will charge to the circuit voltage (a battery will not) and it will hold there. Once the voltage dips, the capacitor becomes the highest source of potential in the circuit and discharges until it reaches the circuit voltage again. Once it reaches the circuit voltage, assuming the heavy current draw is sustained and the voltage is still low, the capacitor does nothing. It does not charge nor discharge.

(If you disagree on this point, look up why current flows. It is basic electronics. It takes a difference of potential "voltage" for current to flow. Current ONLY flows from the highest source of potential in a parallel circuit. Everything else is drawing current off of that source.)

Once the source voltage comes back up, the capacitor instantly recharges with it and therefore has the same potential as the source until it is discharged again.

For this reason, we can see that capacitors do not charge while the voltage continues to dip thus adding more strain on the electrical system. They simply dump their tiny reserve and stay right at the circuit voltage, until the circuit voltage rises again. THEN they recharge.

So, do caps fix things? No. They usually do not have enough reserve or too high of ESR to actually help much. Do caps hurt anything? No, the capacitor will not hurt anything either. It has a very very small potential to help. It has almost no potential to hurt, unless it goes bad.

If you choose to disagree, please provide some substance in your disagreement. Please do not create a flame war. I am attempting to educate you. Please understand that. I am an expert in this field and have several degrees in it.

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[i2ain2thunder 10+ year member]

word caps are a waste of space. get a HO.

 

[bubbagumper6 5,000+ posts]

I usually post this link in Capacitor threads...I have it bookmarked //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

:: NANOPULSER.COM.SG ::

 

[Buck 5,000+ posts]

I think this would be an easier read if you spaced your paragraphs apart a little.

 

[MoZ 10+ year member]

So it begins....

 

[Tormented 10+ year member]

Are their people who believe in capacitors still? I thought everyone who knew anything knew they were useless. Not downing the write up from the op, just curious.

 

[Buck 5,000+ posts]

Batcap may make the only useful capacitor, has a 2 seconds of reserve power at 100 amps. Even at that, it would only work for so long, you'd still need a proper charging system.

 

[ahole-ic]

Are their people who believe in capacitors still? I thought everyone who knew anything knew they were useless. Not downing the write up from the op, just curious.

It's not just about capacitors. It's about batteries too. I just knew the title and subject "capacitors" would get the most interest.

There are a lot of people on here that think the stereo draws current from the battery and then alternator just recharges the battery. I've had several discussions with people on here who think that is true and it's just not. This discussion proves that. If you believe a battery discharges all the time to the amplifier, then you also believe a capacitor has much more storage than it really does and could actually do some good.

 

[Buck 5,000+ posts]

It's not just about capacitors. It's about batteries too. I just knew the title and subject "capacitors" would get the most interest.There are a lot of people on here that think the stereo draws current from the battery and then alternator just recharges the battery. I've had several discussions with people on here who think that is true and it's just not. This discussion proves that. If you believe a battery discharges all the time to the amplifier, then you also believe a capacitor has much more storage than it really does and could actually do some good.

Explain about the batteries, I would like to hear this.

 

[bubbagumper6 5,000+ posts]

Explain about the batteries, I would like to hear this.

It's the same concept as capacitors, current can only flow from a higher potential to a lower potential. So the battery will be doing nothing so long as the system voltage is higher than the battery's resting voltage.

 

[LosIsATool 5,000+ posts]

So wouldnt there draw be the same as adding another amplifier in a sence. So if you dont have the proper system to supply that added amplifier it could harm?

 

[Buck 5,000+ posts]

Oh ya, thought it was more complicated.

 

[ahole-ic]

Explain about the batteries, I would like to hear this.

It's the same principle as capacitors, only worse with batteries. ALL CURRENT IS DRAWN FROM THE HIGHEST SOURCE OF POTENTIAL in a parallel circuit. Since the alternator is charging everything else, it is the highest source of potential. Nothing could ever be higher than it, and only a capacitor can be AS high as it. A battery will charge up to around 12.8 - 12.9. It will float higher than that. Measuring your battery right after shutting off the engine or taking it off of the charger, you will see a voltage in the 13's. Now, give your stereo one solid burp. It doesn't have to be all the way up. Just something to draw a little current. Now measure again.

Just a few amps drawn, will take that float charge away (so will just sitting for 24 hrs) as it's just a tiny charge above the resting voltage. You will now see that you're around 12.8v. This is because that's actually the maximum the battery can charge up to. Since that's it's voltage, the source voltage has to drop below this for the battery to begin discharging. So, until the voltage drops that low, the battery is charging. This makes it a parasitic drain on the alternator at all times until it discharges. For this reason, a battery cannot cure voltage drop unless your old battery was just bad and had an excessive parasitic drain. ALL battery banks do is hold the voltage above 12v. They are there to protect your amplifier from being exposed voltage drops where your alternator cannot meet the demand.

 

---------- Post added at 03:40 PM ---------- Previous post was at 03:40 PM ----------

 

So wouldnt there draw be the same as adding another amplifier in a sence. So if you dont have the proper system to supply that added amplifier it could harm?

No.

 

[i2ain2thunder 10+ year member]

Well a better battery than stock will certainly help as most systems will drop voltage below 12volts. This is where the battery does matter in how much power it can put out how quickly, stock batteries aren't good enough to supply a system proper power. To me, when a system is being used it becomes like a balance of power between all of the electrical components.

 

[Buck 5,000+ posts]

Even a lot of batteries aren't enough to supply a high current system, you have to have a good charger (which I do not have).