Capacitors? Where's the proof?

[power-fanatic07 5,000+ posts]

Guess i need to get me a good capacitor..........................

No such thing, that's like saying I need to get me a clean hooker.

 

[LiveAudio911 10+ year member]

They only recharge once system voltage increases. To say they recharge in milliseconds is to ignore this fact and imply what anwaypasible was saying, that they increase demand on the alt when current draw from the amplifier is at its peak.

Actually it would be 'technically correct' to put it like this.. once they discharge they are going to pull demand on the system rather you have it or not..

So what winds up happening is your amp trying to pull power and the capacitor trying to pull power all at the same time.. with all things equal what will ultimately happen to say the least is max out the electrical system..

So then in this type of case if there is not enough supply for both the cap/amp.. the system is going to be in this cycle.. you'll get degraded w.. from the amp being they are both trying pull energy..

The main principle they are useless as Tits on a boar hog and do more harm than good.. I mean if you had like a hudge monster it might be able to do better than a few Fareds but still...

Lack of power is a lack of power in any form.. the only real way to fix an electrical problem is better batteries (more if one will not store enough power) and upgraded alt to supply the proper amperage..

The Alt is the source of all electrical power.. if your pulling more than it can produce at some point your going to starving the amp and electrical system for power maxing out the system.. which in the long run can damage the ALT.. and battery.. and your equiptment..

Bottom line again.. Upgrade battery.. Big 3 and wires all running proper quality wire and size, and upgrade the main problem The ALT..

 

[power-fanatic07 5,000+ posts]

Actually it would be 'technically correct' to put it like this.. once they discharge they are going to pull demand on the system rather you have it or not..
So what winds up happening is your amp trying to pull power and the capacitor trying to pull power all at the same time.. with all things equal what will ultimately happen to say the least is max out the electrical system..

So then in this type of case if there is not enough supply for both the cap/amp.. the system is going to be in this cycle.. you'll get degraded w.. from the amp being they are both trying pull energy..

The main principle they are useless as Tits on a boar hog and do more harm than good.. I mean if you had like a hudge monster it might be able to do better than a few Fareds but still...

Lack of power is a lack of power in any form.. the only real way to fix an electrical problem is better batteries (more if one will not store enough power) and upgraded alt to supply the proper amperage..

The Alt is the source of all electrical power.. if your pulling more than it can produce at some point your going to starving the amp and electrical system for power maxing out the system.. which in the long run can damage the ALT.. and battery.. and your equiptment..

Bottom line again.. Upgrade battery.. Big 3 and wires all running proper quality wire and size, and upgrade the main problem The ALT..

The underlined statement is false IMO. If you have a big bank of 3100's with a single 300a alt you can easily run 10kw+ depending on how many batts you have.

 

[DBBOOM 10+ year member]

No such thing, that's like saying I need to get me a clean hooker.

Ok, i'll just get a bunch of bad ones.................................like i do with hookers.

 

[roarzorz 10+ year member]

Ya'll have fun with your cute lil capacitors.

 

[LiveAudio911 10+ year member]

The underlined statement is false IMO. If you have a big bank of 3100's with a single 300a alt you can easily run 10kw+ depending on how many batts you have.

Your correct.. if you have enough batteries and they store enough power to provide the draw amperage wise.. to make up for the lack coming from the ALT you sure can.. the ALT has a better chance to recharge the batteries between power demands /slops/musical notes during transitions..

But again thats the key.. Batteries are different than caps, as they actually store and retain voltage and amperage..

That part is more dependent on actual setup..

If you take my example.. if i put like 3~4 batteries i could run it all day long and probally not have to upgrade my ALT, because the 3~4 bats would provide the power I need and the alt would have a better chance of recharging..

If I took the same example and only had 2 batteries... the ALT would work harder.. and probably have a 50/50 chance vs the 4 bats.. of either sufficing or having he same problem..

Again dependent on the setup.. but for the most part.. people looking through these threads are probably running stock Alt.. if they were even considering a cap and wont be putting over sized Bats in front and back.. as they are probably not going to know how to get the figure they need.. to select the right bats to provide enough power to get away with out upgrading the ALT..

 

[audioholic 5,000+ posts]

Actually it would be 'technically correct' to put it like this.. once they discharge they are going to pull demand on the system rather you have it or not..
So what winds up happening is your amp trying to pull power and the capacitor trying to pull power all at the same time.. with all things equal what will ultimately happen to say the least is max out the electrical system..

Not really. As Ive said several times now, cap voltage will follow system voltage. The cap wont 'try' to pull voltage, it will merely accept the voltage its given. Once the alt is insufficient to provide all the necessary power, and the cap follows the drop in voltage, the cap wont recharge until the system voltage increases. A few people here keep coming back to the idea that the cap and amp will pull current at the same time. This is fundamentally incorrect. Once voltage drops to 12.8 volts (for example, batt voltage), the cap will remain at 12.8 volts and not draw (or try to draw) current until system voltage is raised. At this point, the draw a cap places on system voltage will simply be that of its internal resistance.

This may sound like Im a proponent of using external caps, but that is not true. Capacity becomes an issue at this point. The cap will drain its stored power very quickly, again to follow the drop in system voltage, and then it merely becomes an added strain on the alt/system voltage (in the form of its ESR). This added drain is not in the form of drawing the power to recharge (as recharging in this example would be to raise its own voltage), but in the form of merely being an added resistance (ESR) to the system that would otherwise not be there.

Lets make this a bit simpler. To 'recharge' the cap would be to raise its voltage back to 14.4. If the amplifier is drawing enough power to lower to lower system voltage to 12.8 (batt voltage), its physically impossible for the cap to recharge to 14.4 volts. It cannot exist at 14.4 volts while the rest of the circuit is still holding at 12.8 volts. So you could say both the amp and cap will try to draw power at the same time, but reality is the cap will not actually pull the power from the alt until the alt has caught up and is raising system voltage above that 12.8.

 

[audioholic 5,000+ posts]

But again thats the key.. Batteries are different than caps, as they actually store and retain voltage and amperage..

Within that context, both caps and batts work the same fundamental way. The only difference is the cap, due to its lower ESR, will replenish its voltage slightly faster than the batt. caps 'store and retain' voltage just like a batt, but simply transition between voltage differences faster, again due to the lower ESR.

 

[axeten 10+ year member]

It does make sense that a cap wont pull power while your amp needs it.

In simple terms i see it like this:

Lets say your amp is a big pump pulling fluid from a tank (your alternator)..... If there is a small tank (the capacitor) connected to the same line so the pump (Amp) can be pulling from both. Lets say the small capacitor tank runs dry. Your pump (amp) will still **** power from your big tank (alternator) but the little tank wont fill till the pump stops *******..... So the alt supplies the amp as this is the easiest flow path for the electricity. Once the amp no longer needs the power it will redirect to the cap as this has become the easier path for the electricty to go.

This is the way i see it since it is called current "draw" from your electrical system. Not current "push" from the source.

I'm only looking at it this way as we have "accumulators" for fuel oil and hydraulic operated valves at work which help support a loss in supply pressure. I'm in no way saying this is true or this is how it works. Just sortof how i see it without all the big words //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

There's obviously a big split in what people think which is why i started this thread. Atleast it can all be in one thread and someone like myself on a boring night shift can read the whole 100 pages in a year or so and decide what to do.

 

[audioholic 5,000+ posts]

It does make sense that a cap wont pull power while your amp needs it.
In simple terms i see it like this:

Lets say your amp is a big pump pulling fluid from a tank (your alternator)..... If there is a small tank (the capacitor) connected to the same line so the pump (Amp) can be pulling from both. Lets say the small capacitor tank runs dry. Your pump (amp) will still **** power from your big tank (alternator) but the little tank wont fill till the pump stops *******..... So the alt supplies the amp as this is the easiest flow path for the electricity. Once the amp no longer needs the power it will redirect to the cap as this has become the easier path for the electricty to go.

This is the way i see it since it is called current "draw" from your electrical system. Not current "push" from the source.

I'm only looking at it this way as we have "accumulators" for fuel oil and hydraulic operated valves at work which help support a loss in supply pressure. I'm in no way saying this is true or this is how it works. Just sortof how i see it without all the big words //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

There's obviously a big split in what people think which is why i started this thread. Atleast it can all be in one thread and someone like myself on a boring night shift can read the whole 100 pages in a year or so and decide what to do.

Your tank analogy is a reasonable parallel, but not exact. The key to understanding how the cap functions is understanding that it follows system voltage, which is why Ive mentioned that in just about every reply in this thread. The cap isn't "trying" to "pull" current, it simply recharges once the system voltage increases. To use the tank analogy, assume the system is not pressurized (hydraulic systems are pressurized, obviously). If the tank/water system is not pressurized, the water level in all tanks (large being the batt, small being the cap) will remain at the same elevation due to gravity. When the outlet drain of water (the amplifier) stops or subsides to the point the refill pump (the alt) pumps more water than the outlet drain removes, the water level in all tanks rises. This water level rise is similar to system voltage increasing. People who think the cap will pull current even while the amp is still over taxing the alt, think in a way that would presume the small water tank would fill to a higher point than the water in the rest of the system, which it will not do.

Hope that clarifies things more.

 

[bubbagumper6 5,000+ posts]

It was Manville Smith and Lucio Proni @ JL. Their consensus was that even a framed vehicle was on average about as good a conductor as a single run of 4ga.

That's really interesting if that's true...

 

[bubbagumper6 5,000+ posts]

Within that context, both caps and batts work the same fundamental way. The only difference is the cap, due to its lower ESR, will replenish its voltage slightly faster than the batt. caps 'store and retain' voltage just like a batt, but simply transition between voltage differences faster, again due to the lower ESR.

On a technical scale, batteries have a much larger Energy density (5-150 Wh/kg) while Caps only have about 10^-2 Wh/kg. But Capacitors have a much larger Power density (1,000-10,000 W/kg) while Batteries are around 10-500 W/kg.

hehe, Electromagnetics FTW

 

[audioholic 5,000+ posts]

On a technical scale, batteries have a much larger Energy density (5-150 Wh/kg) while Caps only have about 10^-2 Wh/kg. But Capacitors have a much larger Power density (1,000-10,000 W/kg) while Batteries are around 10-500 W/kg.
hehe, Electromagnetics FTW

Will you have my babies?

 

[bubbagumper6 5,000+ posts]

Will you have my babies?

haha, maybe...

Although in all honesty, I don't have those numbers memorized (just the concepts), my Fundamentals of Electromagnetics book is sitting right next me //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[RAM_Designs 5,000+ posts]

I've used a cap in the past, 7 or so years ago...it definitely helped keep voltage from really dropping at all(13.8V or so at the lowest) when I was having dimming issues before and dropping to ~13V without it. I think for lower power setups that just barely exceed the amperage that the alt can support, they work well in keep voltage steady, but in a high power setup it'd be worthless to use one.