caps - what do they do or what do they supposedly do?

[CarAudioAddict 10+ year member]

This what I understand from everything I've ever heard/read on Caps (excluding this thread):

1. Caps store electrical energy

2. Caps can release (discharge) this energy extremely fast (micro-seconds)

3. While the discharge is quick, they take a bit of time to recharge in comparison (milli-seconds)

4. They will not increase the capacity of an already insufficient power system

5. By providing fast, easily available power storage, Caps help your amps can run at full power longer without drawing off your battery (milli-seconds longer, depending on Cap size and amplifier draw)

6. After discharging, the cap must be recharged, which puts an addittional drain (though momentary) on your cars power system.

7. Dimming headlights is often a sign of a weak charging system, and while a cap may ease this problem, it is only a band-aid (actually even worse as the extra draw caused by the recharge cycle will further weaken the charging system)

8. Without Diodes, a Cap affects the entire electrical system, not just the component it is attached with.

9. The best place to install a cap is near the component that needs the extra power. Although Caps affect the entire system, resistance in wires will reduce the effectiveness of the Cap when the device that demends the current is farther away

10. Caps are not a source of power, they must be charged everytime you start your car, and everytime you draw off of them.

They way I've always thought of Caps, is the same as a reservoir in a water system. When a towns (electrical system's) demand for water (power) is low, the pumps (alternator) can supply the water. But when demand is high, the reservoir will be drained until one of three things happens:

1. Demand goes down and the pumps can refill the reservoir

2. The reservoir is completely drained, in which case the town will suffer from a water shortage

3. More water is dumped into the reservoir (ie. rain, or tankers)

#3 above would be the equilivant of the battery supplying power after the cap is discharged below battery voltage

 

[ngsm13 5,000+ posts]

ive had a soundstream 10.0 that dimmed my lights i added a cap and the dimming went away ..thats real world application no theory behind it ...theres another guy in this argument ..i mean post who had the same luck ..tha fact is caps seem to work for a lot of people and for alot of applications ...ive been looking and the biggest aqlt i can find for my application withount fabbig up brackets is a 90 amp ...so ill be running a yellowtop out back with caps ...

http://www.excessiveamperage.com

also, i ain't touching a cap...useless. I got a 220 amp alt...close to 3000 watts of rms power...a red top under the hood and a yellow top in the rear...all wiring upgrade to 1/0 for power and ground....big 3 upgraded...and NO DIMMAGE OR VOLTAGE DROPS for any daily situation. peace

NG

 

[slick rick 10+ year member]

quick questions, what exactly is the big 3? i know its an old thread, i just searched.

 

[adam71 5,000+ posts]

This question is for helotaxi. I run a system with 4 amps as you see at the bottom of my posts. I don't have a cap in my system and I noticed my lights dimming when I cranked my system way up. They only dimmed on hard bass hits. I have 2 new 1F capacitors that I'm going to install as soon as the weather breaks. I'm using 2 amps for subs and therefore 2 caps. In your opinion, which I trust after reading your earlier posts in this thread, will these capacitors potentially help my problem.? Granted I don't get on my system that loud too often which is why I haven't spent the money on an alternator upgrade. I am however on my 3rd alternator for this car but I figured the other ones fried because I was cranking my system with the AC running at the same time.....stupid. Well any input you can give I would very much appreciate. Thanx.

Adam //content.invisioncic.com/y282845/emoticons/smokin.gif.f1dc8d2acb1809e863ebd6a47eaa0d45.gif//content.invisioncic.com/y282845/emoticons/crazy.gif.c13912c32de98515d3142759a824dae7.gif

 

[helotaxi 5,000+ posts]

A few questions...How big is your alternator? How big is your power wiring? Have you upgraded the ground strap for your battery and engine block and upgraded the positive wire from the battery to the alternator (slick rick those are the BIG 3)? If your main power wire is anything less than 4 ga you are wrong and I would be running at least 2 ga. Your alternator wire should be at least 4 ga. The battery ground should be the same size as your primary power wire. If the wiring isn't up to the task, especially under the hood, then the caps won't help at all. Those caps can help to lower the peak current demanded from the alternator and keep it from getting over tasked during music peaks, but the system will draw more than it ordinarily would for a second while the caps recharge back to the voltage level of the alternator. Your lights may still dim but it will not be as noticable because the caps will ease the transition between the 14V of the alternator and the 12V of the battery so it will be a slightly more gradual dimming and the voltage may only dip to say 13V because the caps don't discharge below that level. You won't know until you install them. They probably won't hurt and they may help, you never know until you try and since you already have them, you may as well try.

 

[Diplexers 10+ year member]

You're all crazy. I'm running 55, 1 farad caps to my Jensen amp which is moving my legacy 8" subs and hitting 168db................................. //content.invisioncic.com/y282845/emoticons/offwall.gif.29a91b9b265d47af4b8e33fc5b558d18.gif

 

[valant_94gt 10+ year member]

magic 3 ?? hmmmmm...... whats that ?

going from 8guage to 4guage would ake a difference?

I'm going to run 1, 200 watt amp for components and 1, 1200 watt amp for 1 12" 1200 watt sub. should i buy an alt ??or just upgrade wiring and add a cap. 1.5f ??

my whole outlook on caps has changed. always look deeper into the root of the problem. i'm on the fence here.

 

[adam71 5,000+ posts]

A few questions...How big is your alternator? How big is your power wiring? Have you upgraded the ground strap for your battery and engine block and upgraded the positive wire from the battery to the alternator (slick rick those are the BIG 3)? If your main power wire is anything less than 4 ga you are wrong and I would be running at least 2 ga. Your alternator wire should be at least 4 ga. The battery ground should be the same size as your primary power wire. If the wiring isn't up to the task, especially under the hood, then the caps won't help at all. .

Ok, my power wire back to the trunk is 1/0. My ground for my batter is also 1/0. The wire from the alt to the battery is still stock which is also on my project list of things to do. The alternator I believe is whatever GM puts in their cars. This is the 3rd alternator for this car (as I said in the last post) and I didn't tell my mechanic to upgrade to a higher amperage, I just told him NOT to put another Delco piece of **** in there. So whatever that is in amps is something I don't know without looking. I would ask my mechanic but he died last summer. But with that being said I'm going to put them both in this spring.

Adam //content.invisioncic.com/y282845/emoticons/suave.gif.858fc102f7646e678ee8af7e1fbc41d1.gif//content.invisioncic.com/y282845/emoticons/wacky.gif.cf4a48f9e6dfe9504ffd2c946fd2f340.gif

 

[Bodawg111 10+ year member]

Would a cap make my 1000 watt respond any better even though my lights arent dimming? or would it be a waste of my hard-earned dollars?

 

[CarAudioAddict 10+ year member]

Would a cap make my 1000 watt respond any better even though my lights arent dimming? or would it be a waste of my hard-earned dollars?

Take a volt meter and measure the Voltage at the Amplifier. Take the measurement while playing music that will make your Amp drive the hardest (in this case I'd guess subs).

If the voltage drops below 12.6 volts then a cap will possibly help.

 

[audioholic 5,000+ posts]

"upgraded" alternators often don't deliver much more idle-RPM current than stock alternators

"upgraded" alternators inherently rob horsepower, proportional to their increased size, by their larger drag on the motor at all RPM's

alternators are expensive, and possibly not available as a bolt on... rewinding a stock alternator leaves reliability concerns

if you have enough power in your car to actually seem to justify an alternator upgrade, and you can actually stand to be in the vehicle, under those conditions, for time periods long enough to seem to justify an upgrade - the alternator isn't your problem. You need to track down serious inefficiencies in your system.. in other words, you could be (should be) getting more output, with less power.

the money spent on an alternator could be more usefully spent elsewhere."

You frown on upgrading an alternator for these reasons? hmm okay. You judge a systems effeciency on whether or not a stock alternator can keep up with it? hmm okay. Which stock alternator are you talking about? because I know stock alts can go anywhere from 50amp to 120+ amp. Which of these sized alts are you using as your golden line as to a good draw on the charging system? The bottom line is the alternator is the only piece of your car's electrical system that actually produces energy, and if your draw is larger than your alternator's output (over time if you want to split hairs), you need to upgrade your alternator. If your alt doesn't keep up with the draw on it, upgrading wiring, batts, adding batts or caps, etc is only a shell game.

As for the earlier discussion of why to mount a capacitor as close to the battery as possible, it has nothing to do with the speed of electrons (lol tho), it has to do with voltage and resistance.

 

[Diplexers 10+ year member]

resistence is a fickle thing. //content.invisioncic.com/y282845/emoticons/wave.gif.002382ce7d7c19757ab945cc69819de1.gif

 

[helotaxi 5,000+ posts]

because I know stock alts can go anywhere from 50amp to 120+ amp.

At least 160A. Someone was actually thinking when they built my car, especially since no one makes a bolt on for it.

 

[audioholic 5,000+ posts]

"At least 160A. Someone was actually thinking when they built my car, especially since no one makes a bolt on for it."

Yep that's true. Ive also heard of stock alts going as low as 20 amp (on old cars). But I wanted to keep my range in the middle so it wouldn't look like I was using an extreme to prove my point. The point of course, was that judging your system's performance based solely on if the stock alt keeps up is nonsensical.

BTW you were lucky, my last car had a stock 90amp. 90 amps was with max with the casing size so no respin was possible, and it was the only case size made for my car.

Speaking of which, anyone recommend a good class D amp? lol Im looking to get a new sub amp, mmats still pretty much the best?

edit: I really should start using the quote feature properly

 

[helotaxi 5,000+ posts]

The point of course, was that judging your system's performance based solely on if the stock alt keeps up is nonsensical.

True.

BTW you were lucky, my last car had a stock 90amp. 90 amps was with max with the casing size so no respin was possible, and it was the only case size made for my car.

I was lucky. I bought the car more for transportation than for a rolling stereo, but since I had the equipment...I already had the car and was plesantly surprised when I found out that the alt. was a monster.

Speaking of which, anyone recommend a good class D amp? lol Im looking to get a new sub amp, mmats still pretty much the best?

How much power you want?

edit: I really should start using the quote feature properly

Yeah, what's up with that...sheesh... //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif