Capacitors? Where's the proof?

[helotaxi 5,000+ posts]

^^^ You have a gross misunderstanding about how caps "work."

 

[helotaxi 5,000+ posts]

Wasn't it Richard Clark and David Navone that tested a bunch of typical cars like 10 years ago to measure their potential chassis resistance. IIRC, their conclusion was framed vehicles tend to have more potential for passing current thru their chassis efficiently than do unibody vehicles, but even that was not set in stone. Other intangible things like batt location, stock wire type/location, and even the specific design of the vehicle (how panels are joined, where, how well) all factor in to the efficiency of its chassis ground. I believe their final recommendation was if at all in doubt, run a dedicated ground cable.

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.

 

[audioholic 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.

Thanks for the clarification.

 

[audioholic 5,000+ posts]

i think this debate is often called upon by people who are willing to let other people speak.
you dont need a large article about the use of capacitors.. and i will show you why below:

first you start up your car and let the capacitor fill up **this event has a name and a value.. making some caps better than others**

then you turn on your radio as you drive down the road.. (does the amp feed from the capacitor or does it feed from the alternator.. or both?)

**this event/threshold has a name and a value.. making some caps better than others**

lets just say for example that the amp is pulling from the alternator as you drive down the road.. the cap is just sitting there all filled up.

then you come to a stop light and the alternator starts to spin much much slower because your engine is idling and the belt that spins the alternator isnt moving as fast.

when this happens, the alternator puts out less electricity.

so the amp ***** up all the electricity that the alternator is putting out and requires more.. this is where your capacitor kicks-in and provides electricity.

how long will the cap provide electricity and how much electricity?

** these events have a name and a value.. making some caps better than others**

if the light turns green before your capacitor gets low on stored energy, then the alternator will start to spin faster as you start driving forward.

and this is a perfect time to explain one reason why your alternator needs to be large.

once you have pressed the gas, the belt that spins the alternator moves faster, and the alternator starts putting out more electricity.

the amp starts ******* electricity from the alternator again and the capacitor recharges itself with whatever electricity is left.

**this event/threshold has a name and a value.. making some caps better than others**

an ideal cap would wait patiently to get recharged and also not require lots of electricity to recharge itself.

because a cap that isnt ideal would **** really hard on the electricity wire and the alternator will suffer from abuse with the amp ******* hard and the capacitor ******* hard at the same time.

its like having a huge amp on a stock alternator.. the amp is going to **** on the alternator until the alternator fails.

if you have a decent size stock alternator.. and your capacitor waits patiently to be recharged.. and your amplifier isnt drawing more electricity than what the alternator can provide (above engine idle) then it's safe to say that your stock alternator isnt going to fail or suffer from abuse.. and you have added a patch to your electrical system that will keep the voltage from dropping while the engine is at idle (that is, until the cap goes dead)

there is no sense with reading those large articles about the results they received when testing their capacitor, because there is no evidence that the capacitor was an ideal capacitor.

the people who wrote the article might have chosen a piece of junk that has all the wrong values for providing voltage at the stop light and slowly recharging after the light turns green.

some caps will wait for the voltage to reach 13v or 12v before it starts to release its stored electricity **again, this event has a name and a value.. making some caps better than others**

these caps will show voltage bouncing around because the cap is waiting.

some caps will not wait for the voltage to reach 13v or 12v.. probably because they are designed to start giving out electricity at a higher voltage.. 13.5v or 14v

and these caps will keep the voltage readout 'stiff' and free from fluctuations as long as the capacitor has energy stored.

how do you know if your capacitor is junk?

if you come to a stop and the lights continue to dim, there is something wrong with the way your capacitor is designed.. try a different brand name or model number.

dont worry too much about the voltage readout bouncing around a little bit, as long as the lights arent dimming, there isnt a solid problem.

the lights are the key piece of evidence you should use to ensure that your amplifier is getting electricity through a thick straw rather than a little one.

i am sorry.. i do not know the names of each event, nor do i know what the ideal values are.

but understand that not all capacitors are made equal.. some offer the same 1 farad value, but perform differently for reasons and examples mentioned above.

***edit***

also understand that there are lots of amplifiers that can run on a stock alternator when the engine IS NOT idling.. which is like 1,000rpm's or higher.

so if your RPM's are 1,000rpm or higher.. the stock alternator can give 100amps or whatever the rating is.

at idle.. the amount of amperage goes way down and your amplifier gets thirsty.

so people suggest that you upgrade your alternator BECAUSE the bigger alternator will put out more electricity when the engine is idling.

the key word here is 'when the engine is idling'

you probably wont use up all of the electricity from a bigger alternator when the engine is at 1,000rpm's or higher.

what you are craving is the power at engine idle.

a capacitor can provide that power at engine idle.. but if your system is too big, you are going to need larger amounts of stored energy.. and that means more recharge when the light turns green.

so it is best to keep your amplifier from getting thirsty.. and whatever electricity is left-over can recharge the caps.

I wish this reply was not in the stickied thread on caps, its full of grossly incorrect information.

"an ideal cap would wait patiently to get recharged and also not require lots of electricity to recharge itself."

There is no such thing as 'patient' caps. A cap has two basic elements to consider, ESR (equivalent series resistance), and capacity. Generally speaking, the higher the capacity, the higher the ESR. This is why its better to have a bank of smaller caps, as opposed to one single large cap. There is no design element of a capacitor that makes one more 'patient' than another.

A capacitor follows the laws of physics, there is no such thing as a cap that 'doesn't require a lot of electricity to recharge itself'. When a cap drains, and then recharges, it will require the same amount of energy to recharge as it had dissipated when it discharged, plus a little both ways for internal resistance (ESR).

"some caps will not wait for the voltage to reach 13v or 12v.. probably because they are designed to start giving out electricity at a higher voltage.. 13.5v or 14v"

I already explained this earlier in this thread. The cap's charge will follow system voltage. When the engine is off and the alt is not powering the charging system, system voltage will rest at whatever the battery's voltage is (usually around 12.8 volts for a healthy batt). Once the engine is started and the alt provides power, system voltage jumps up to what the alt provides (usually in the 14.4 volt range). The cap's charge follows this voltage variance, period. How a cap actually discharges (provides its stored energy to the amplifier) is when the alt's power supply becomes inadequate, system voltage will dip out of the 14.4v range. When this happens, the cap's voltage will dip as well. Its that dip in the cap's voltage that is the cap actually discharging and providing its stored energy.

"because a cap that isnt ideal would **** really hard on the electricity wire and the alternator will suffer from abuse with the amp ******* hard and the capacitor ******* hard at the same time."

100% incorrect. Again, I already explained this previously in this thread. Its a common misconception that a cap discharges all its stored power immediately, and then will demand current from the alt to recharge just as quickly. This is not the case. Again, the cap will simply follow system voltage. If the amplifier's current draw exceeds the supplied power from the alt, system voltage dips. This dip in system voltage includes the cap's voltage (as the cap discharges while trying to make up for the lack of power from the alt). The cap will NOT try to recharge until system voltage increases. And when does system voltage increase? It increases when the alt's power supply becomes sufficient to handle the current draw on it again (iow, when the bass note stops or subsides). So knowing this, we can conclude that the cap and amplifier will NOT draw 'really hard' on the alt at the same time, quite the opposite. In fact, one could successfully argue that a cap will actually help prolong alternator life by helping reduce these peaks in current demand the amplifier places on it.

No offense to you, because you are learning and none of us started off knowing everything, but like helotaxi said, your understanding of how caps work is very misinformed. If you have any questions on what Ive said here, feel free to ask.

 

[LiveAudio911 10+ year member]

Caps wont help you... simple principle... they sputter out all the energy they have once the system V drops below 12.x (forget the correct figure) they are supposed to stiffen the power to prevent this, but the way they work is they do not discharge untill you drop low.. thus a catch 22... then they sputter out what little bit of power they do have..

My amp would **** that little bit of power in half a wave... then the cap has to recharge it self by ******* like a vacum all the energy it can from the battery.. and if your problem returns if your amp/battery can not supply enough power before you placed the cap.. what makes you think it will do anything after?

The energy comes from the battery which comes from the Alt.. if either one of those can keep up, plain and simple wont keep up with the Cap too and will do more harm than good..

For those that actually see a difference It is probably because you basically turned it into a dist block if you connected it properly.. and caused a more stable less ohm ground.... or something along those lines..

Even putting a second battery in the back is only masking the problem.. at some point both the batteries have to be recharged.. if your alt cant keep up with one battery and your system its not going to do that great of a job for the 2.. at some point you will have to upgrade the alt.. or you can just continue on as-is and have to recharge the battery manually, or rely on the alt while not taxing the electrical system by turning off your equipt. so it can recharge..

All electrical problems:

1. Big 3 Upgrade.. (Plus some extras)

2. Upgrade your stock battery

2.1 Place 2nd battery if you really need it

3. Upgrade your alt...

Simple: Figure out your maximum vehicle draw (amps wise) then figure out what each amp's max draw is.. (amp wise) add it all up..

Example: My Truck: 80amps, Amp 1 25amps, Amp 2, 120 amps) add it all up 225amps maximum draw potential.. so that means I need an alt that can supply at least 225 amps... or higher..

To be honest your probably not going to ever hit maximum draw like that fully, on a daily driver.. but you might.. so if your going to spend the money on something make it count.. do it right and dont suffer the pain of trying a bunch of crap that never works..

Just upgrade your bats and alt as $$ allows..

 

[audioholic 5,000+ posts]

Also filled with incorrect information. We need a whole new sticky. Jesus Christ almighty.

 

[LiveAudio911 10+ year member]

What part of that is incorrect?

 

[audioholic 5,000+ posts]

What part of that is incorrect?

"then the cap has to recharge it self by ******* like a vacum all the energy it can from the battery"

 

[LiveAudio911 10+ year member]

I'm just gonna laugh.. because that is exactly how they work.. they discharge/recharge in milliseconds.. as long as the power is available..

Connect one up with out charging it first and see how much of a drain they instantly put on the system.. they do the same thing as they are running discharging/recharging..

 

[audioholic 5,000+ posts]

To be fair, Ive been drinking. The rest looks fairly accurate, but Im not in much of a condition to examine the details right now.

 

[power-fanatic07 5,000+ posts]

meh

 

[LiveAudio911 10+ year member]

HA HA! Pass one my way.. I'm at work bored as hell.. ROFL

 

[audioholic 5,000+ posts]

I'm just gonna laugh.. because that is exactly how they work.. they discharge/recharge in milliseconds.. as long as the power is available..
Connect one up with out charging it first and see how much of a drain they instantly put on the system.. they do the same thing as they are running discharging/recharging..

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.

 

[audioholic 5,000+ posts]

HA HA! Pass one my way.. I'm at work bored as hell.. ROFL

LOL roger that bro.

 

[DBBOOM 10+ year member]

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