8th Generation Honda Civic Forum - View Single Post

aeroes · 04-04-2008, 11:19 PM

WHAT IS A CAPACITOR GOOD FOR?

1. Audio Jewelry- impress chicks with large cylindrical shiny thingy
2. Extra weight in winter time
3. A very POOR... BUT expensive distribution block
4. A projectile in the event of a crash
5. Rolling pin--for cooking purposes
6. A neat thing to tell your friend, "..Hey man, lick the top of this..

WHY?? READ:

WHY DO PEOPLE BUY CAPACITORS?

The number 1 reason would have to be because their lights dim when their
system is playing HARD. In car audio, we are told that a capacitor is
designed to prevent the voltage drop associated with your lights dimming.
The number2 reason is that it is rumored to 'improve' sound quality or
'stiffen' the power supply/source.

WHY DO MY LIGHTS DIM?

Headlights brightness is in direct proportion to the source voltage. For
instance, if your car is running, system voltage is ~12.5 -14.4 VOLTS. Your
lights will be much brighter than when your car is turned off--where battery
voltage is ~12V. Most car alternators put out between 75 to 120 amps of
current. When this current draw threshold of the charging system is
exceeded, system voltage will drop as power demands are now shared by the
alternator and the storage devices (battery & cap). We are using battery
reserves beyond this point until the demand lessens

When playing your system really hard. Your lights dim because your
alternator can't keep up it's charging voltage (around 13.5V) and therefore,
demand exceeds output. When this happens, your electronic devices are
dipping into the power storage of the battery. Since the battery stores
power at ~ 12-12.5V, there is a 1.3 to 1.8V drop in voltage available. This
in turn is why your lights dim down.

HOW MUCH POWER DOES A CAPACITOR STORE?

1 Farad = 100 joules or 100W/second
850cca battery = ~2,200,000 farads

For storage purposes, you'd need ~2,200 1 Farad capacitors to equal the energy of your battery.

Due to its impedence (ESR & ESL), a cap's energy is only 50% available. What's worse, is that in order for a 1 Farad cap to discharge, first the alternator output must have maxed out, and the voltage must have dropped around 1.5 volts. But I thought a cap was supposed to prevent that (voltage drop)!!!!!????? Yep, you got the point.

IF A BATTERY = 2,200 CAPS, THEN WHY BUY A (PUNY) CAP?

My question exactly. Marketing is the reason why people buy caps. In many cases, upgrading wiring will help your system get the maximum transfer of current. Once that has been reached, adding a capacitor may have a minor effect on your system. 50W over the course of a second is not a lot of power considering an amplifier may draw 2000W to put out 1400 watts. Let's look at the situation from a resources standpoint.

These were copied from other forum..

04-04-2008, 11:19 PM	#11 (permalink)
aeroes Junior Member Join Date: Nov 2006 Posts: 19 iTrader: 0 / 0%	WHAT IS A CAPACITOR GOOD FOR? 1. Audio Jewelry- impress chicks with large cylindrical shiny thingy 2. Extra weight in winter time 3. A very POOR... BUT expensive distribution block 4. A projectile in the event of a crash 5. Rolling pin--for cooking purposes 6. A neat thing to tell your friend, "..Hey man, lick the top of this.. WHY?? READ: WHY DO PEOPLE BUY CAPACITORS? The number 1 reason would have to be because their lights dim when their system is playing HARD. In car audio, we are told that a capacitor is designed to prevent the voltage drop associated with your lights dimming. The number2 reason is that it is rumored to 'improve' sound quality or 'stiffen' the power supply/source. WHY DO MY LIGHTS DIM? Headlights brightness is in direct proportion to the source voltage. For instance, if your car is running, system voltage is ~12.5 -14.4 VOLTS. Your lights will be much brighter than when your car is turned off--where battery voltage is ~12V. Most car alternators put out between 75 to 120 amps of current. When this current draw threshold of the charging system is exceeded, system voltage will drop as power demands are now shared by the alternator and the storage devices (battery & cap). We are using battery reserves beyond this point until the demand lessens When playing your system really hard. Your lights dim because your alternator can't keep up it's charging voltage (around 13.5V) and therefore, demand exceeds output. When this happens, your electronic devices are dipping into the power storage of the battery. Since the battery stores power at ~ 12-12.5V, there is a 1.3 to 1.8V drop in voltage available. This in turn is why your lights dim down. HOW MUCH POWER DOES A CAPACITOR STORE? 1 Farad = 100 joules or 100W/second 850cca battery = ~2,200,000 farads For storage purposes, you'd need ~2,200 1 Farad capacitors to equal the energy of your battery. Due to its impedence (ESR & ESL), a cap's energy is only 50% available. What's worse, is that in order for a 1 Farad cap to discharge, first the alternator output must have maxed out, and the voltage must have dropped around 1.5 volts. But I thought a cap was supposed to prevent that (voltage drop)!!!!!????? Yep, you got the point. IF A BATTERY = 2,200 CAPS, THEN WHY BUY A (PUNY) CAP? My question exactly. Marketing is the reason why people buy caps. In many cases, upgrading wiring will help your system get the maximum transfer of current. Once that has been reached, adding a capacitor may have a minor effect on your system. 50W over the course of a second is not a lot of power considering an amplifier may draw 2000W to put out 1400 watts. Let's look at the situation from a resources standpoint. These were copied from other forum.. Last edited by aeroes; 04-04-2008 at 11:21 PM.