Biggiesacks

Capacitors don't store much power. They can deliver a quick burst of a small amount of power. One large bass hit and they are empty. They don't make power, and if your system is lacking that's just one more load that needs to be powered.

Capacitors have a small roll to play for a system that can handle the RMS of a stereo but not the peaks. AFAIK their small roll has been completely obsoleted by lithium batteries, which also have very low internal resistance, but actually hold a lot of power.

They were basically a gimmick or an upsell in the segment of car audio that I worked in a decade and a half ago, and I haven't seen anything since that would change my mind.

Biggiesacks

Like all the other upgrades one can do It's really subjective. Gotta factor in mods you have done to the car that use juice (fuel pump, ignition, widebands, radar detectors, etc.). The climate and the way you use the car also factor in. Maybe you never expect to find yourself in stop and go traffic in severe weather. So it's really hard to give a straight answer. What I can say is with a 400watt amp your not likely to damage the stock electrical. You will obviously need to run power and ground for the amp though, the stock harness if available isn't going to cut it. Then it's a question for your tuner if that power draw is going to negatively effect your fuel pump/injector/ignition system voltage during a pull.

Jp7

iTrader: (11)

The smart way to check this is to understand how your alternator field-coil is controlled. Most of them are pulse width modulated. As the pulsewidth is increased, the regulator is telling the alternator to create more "magnetic resistance" which allows it to generate more current going back to the battery.

If you install a large amplifier and all of a sudden your pulsewidth is showing 90% instead of say 60% (with many loads going at one time) it would be wise to upgrade your alternator.

I can measure this kind of thing with my picoscope.

Also in my 2012 mazda 3 I installed a different amp. It came with a bose amp from the factory, and it sounded like Junk so I completely re-engineered the entire audio system. When I added a capacitor I was surprised it helped with amplifier noise. It would be interesting to monitor battery voltage both with and without the capacitor to understand the difference. (I did not have my pico when I originally did this)

Biggiesacks

Being able to see what the ECU is doing is certainly helpful. We could log that through MUT, I'm sure other OEM's have a way to log that info as well. I've never seen it done that way in the wild though. A current clamp on the alternator wire is easy and universal. You see a lot of old stuff doing audio too, and they don't have those kinds of control signals. My mustang alternator is self regulating for example.

Jp7

iTrader: (11)

The current clamp trick is a fantastic idea but it needs to be done with a scope because the entire point is to see it switching. If you connect your current clamp to a typical voltmeter it will not update quick enough. I probably have a half-dozen DVMs and my fastest one updates about 4 times per second. A Current clamp kit can be a very powerful tool. I use it for many diagnostic purposes, including checking relative compression (cylinder vs cylinder). You can measure the individual cranking current each cylinder enforces to the starter motor during a starting event!

Biggiesacks

Realistically as a mobile electronics installer you just kind of have to assume that all the components in the system can handle all the iso/IEC type transients* and not worry too much about that time domain. That's why it's important to buy quality automotive electronics.

Totally different story when it comes to diagnosing issues though. I'm really just interested in a high level evaluation of the performance of the system under load over a decent amount of time.

* as outline here
https://www.st.com/content/ccc/resou...CD00181783.pdf

mitsuatb

iTrader: (6)

Cap's have far less internal resistance than lithium batteries. Cap's don't have to wait for electro chemical reactions. Music has gaps in amplitude to allow caps to charge. Might help you to read the article.

Biggiesacks

As someone who has done many board level repairs on amps, I can assure you that they already come with their own capacitors.

Biggiesacks

This is on the spectrum of arguing with flat earthers. This stuff is so basic in car audio that not knowing it is either just crazy lazy, or intentionally ignorant. Go spend 5 minutes on a stereo forum, or i dunno just google. It's so basic there is a common name for it called "The Big Three". Spoiler alert, capacitors aren't one of the 3.
Too lazy to do that, no worries here are some nice videos done by a guy that clearly knows what he is talking about.

mitsuatb

iTrader: (6)

If you think its true, then I have no interest. Lots of common knowledge is dead wrong. Take some physics then reconsider.

https://www.crutchfield.com/S-1iYLKY...citor-faq.html

Biggiesacks

arguing with you about this is pointless. You have some kind of ego block going on, and nothing you post is going to change my years of lived experience installing stereos.

Go ahead and buy up your capacitors, enough of your type does, that's why they keep selling them.

mitsuatb

iTrader: (6)

Crutchfield knows nothing about stereos? That's your argument? I am not the one with an ego block, take a look in a mirror.

Mitsuatb

Biggiesacks

did you read the article? I'm not sure what point you think it is making.

Set that aside, no I don't agree with Buck's recommendations.

Notice Crutchfield is only selling 2 capacitors for car audio, made by some obscure off name brand. If these things were a real solution you would see offerings from premium brands.

If you happened to crack open a manual for one of said premium brands amplifiers, you would notice no mention of capacitors. At least not that I have ever seen.

mitsuatb

iTrader: (6)

Yes I read the crutchfield article. Explains how to install caps and why and how to protect yourself from discharge. You have to understand that common caps the size of your finger are rated in micro farad's 1 Microfarad [µF] = 0.000001 Farad [F]. So they recommend a 1 to 2 Farad cap on 1000W RMS system This is 1 to 2 million times the size of a common filter or power cap. These things can easily kill people. They store large amounts of current with almost zero internal resistance or response time. Think 1000 X the power of a CD ignition. Super Cap's are used and proposed as better than batteries. Due to the pulsing of music there is time for them to charge taking surge current demands and perhaps preventing the need for larger alternator. If the power demand is continuous like you were running a search light then they would be of no help.

Biggiesacks

LOL end of discussion. This has been a "Tell me you don't know Car audio ( or electronics ) without telling me you don't know car audio" back and forth and you just finally came to it.

I am familiar with capacitors and their uses. No nobody thinks capacitors are a viable replacement for batteries in all but the most niche of applications. Real supercapacitors these are not, and if you think a 12 volt capacitor can kill you...well clearly you don't know 12 volt either. Why don't you grab a napkin and figure out how many watt minutes a farad is @12volts, then take a look at the RMS current of a decent amp.

The electrical engineers that designed the power stage of the amp would have included any/all capacitors the amp should need for proper operation.