Yo Luke - what's your take on those big capacitors?

[immajackuup]

So whats your take on flickering lights with bas hits?

bad alternator.

[Jean]

Hmmm. I'll have to check what I have. I have a m30b35.

You don't need a cap dude, b35s have manly alternators.

[Jean]

Also consider that car amplifiers aren't exactly using your 12 volts to make music, instead the 12 volts are used internally by a switched power supply circuit to make 2 rails (positive and negative) of 20-50 (on average) and have it's own line of capacitors PER rail to keep the voltage smooth DC like.

So, if you have a shitty amp putting a big cap before it might make a bigger difference vs. putting one on a high end or quality amplifier.

[bloodshot-e30]

i had a 2 farad cap with 1400 watts+ of power and 2 speaker amps and it never dipped below 12.5 volts at idle with my M52 swap

[europeanplates]

I will have to get out my old stereo pictures. I did a couple DB drag cars that had 10 and 14 1 farad units. Do the work? They did in my systems; but these where mega dollars systems.

Tyler

[Schnitzer318is]

LOL... I still think they are a waste of $$$, as Luke does apparently. I'll continue to not use them in my "ignorance."


PS: I also like the pretty digital voltmeter lights that they display, unfortunately they are almost always in the trunk where no one can see them.

[Vtec?lol]

This is the biggest bunch of malarkey this forum has spewn out in, well, days. What you meant to say was your stupid trunk rattling ricer special is killing your charging system.

I guess you could put it that way...

[Jparkr]

Capacitors do what they're designed to do, store charge. If you want snake oil, look no further than this:

http://www.bestbuy.com/site/Fuel+Doctor+-+Fuel+Efficiency+Booster+-+Gray/9754101.p?id=1218170982087&skuId=9754101&st=fuel%20save&contract_desc=null

Were you expecting a free lunch?

As for those of you calling me a stupid college kid, really? Half of the EE students I've met can barely figure out how to test a 9V battery. Most of what I know I learned by doing, reading about it is just good practice. Sometimes it blows up in your face, but most of the time it works just fine.


Well I think there are positive effects. Capacitors have lower internal resistance than batteries, so they'll do more discharging and recharging than the battery, evening out load on the alternator should make life easier for it. Systems at a steady state generally seem to hold up better than those constantly in flux.

Compare it to a well pump that is cycling on and off constantly, and one that is running continuously - the one that is just on will almost always outlast the one cycling on and off.

Wow, you are, like, so..... smart. I'm going to change your name to StereoInstaller2 if you keep it up.














Ps. Don't keep it up. Your opinion was not originally asked for and despite that has already been stated here several times. If you wanna argue such minuscule details, you can go somewhere else.

[u3b3rg33k]

Yo Luke - what's your take on those big capacitors?

Snake oil?
They do what they claim?
What's the deal?

Capacitors do what they're designed to do, store charge. If you want snake oil, look no further than this:

http://www.bestbuy.com/site/Fuel+Doctor+-+Fuel+Efficiency+Booster+-+Gray/9754101.p?id=1218170982087&skuId=9754101&st=fuel%20save&contract_desc=null

After [capacitors] are drained they are just another draw on your alternator.

Were you expecting a free lunch?

As for those of you calling me a stupid college kid, really? Half of the EE students I've met can barely figure out how to test a 9V battery. Most of what I know I learned by doing, reading about it is just good practice. Sometimes it blows up in your face, but most of the time it works just fine.

If a capacitor smooths ripple in the forest, but no one is there to see it, does it really matter?

If everything in the car is built to deal with it, and there isn't any positive effects - so unless you drive around looking at a scope...what's are you going on about? I'm lost. I've missed something.

Well I think there are positive effects. Capacitors have lower internal resistance than batteries, so they'll do more discharging and recharging than the battery, evening out load on the alternator should make life easier for it. Systems at a steady state generally seem to hold up better than those constantly in flux.

Compare it to a well pump that is cycling on and off constantly, and one that is running continuously - the one that is just on will almost always outlast the one cycling on and off.

[george graves]

If a capacitor smooths ripple in the forest, but no one is there to see it, does it really matter?

If everything in the car is built to deal with it, and there isn't any positive effects - so unless you drive around looking at a scope...what's are you going on about? I'm lost. I've missed something.

[u3b3rg33k]

...so if you have a 1800W amp and your pushing 4ohm loads of sub-50Hz bass, your 2farad cap is now leeching and killing your charging system.

This is the biggest bunch of malarkey this forum has spewn out in, well, days. What you meant to say was your stupid trunk rattling ricer special is killing your charging system.

Yea....in theory is should really help everything in the car out - like literally everything that electrical should be able to benefit from it. Why doesn't it? I don't know - maybe the battery's internal resistance is much higher than you expect - just a guess.

Automotive electrical systems aren't like anything else - they are wired in these odd ways, and generally use way too small of gauge wire (somehow getting away with it) and god the noise, alternator load dumps. It's a fucking mess.

In my unsolicited opinion, it does "help". If nothing else, it smooths out alternator ripple current, which, unlike that of a half decent DC power supply, is in the tens of amps (or more), not milliamps. Most things in a car are supposedly built to deal with this: ECU's must tolerate a wide variety of voltages (down to whatever the minimum voltage will be while cranking in the dead of winter with a weak battery), ignition noise, crappy common ground systems *cough* *cough*, etc...

Can the average person notice a capacitor smoothing out ripple? I doubt it. Is removing AC from a DC system a good thing to do? Generally, yes.

As for automotive electrical not being like anything else, I disagree. MOST wiring systems are designed on a budget (thank goodness for the NEC).
The only major difference is the common ground system, which is a stupid way to save weight. I'd rather the car had 75# more copper in it than the weight savings of common ground (it's even worse when sensors are common ground).
What kind of moron would wire a bathroom, a hallway, and an outdoor outlet on the same 15A circuit? The kind that would drop two wire gauges in a car to help out the bottom line.

[george graves]

Yea....in theory is should really help everything in the car out - like literally everything that electrical should be able to benefit from it. Why doesn't it? I don't know - maybe the battery's internal resistance is much higher than you expect - just a guess.

Automotive electrical systems aren't like anything else - they are wired in these odd ways, and generally use way too small of gauge wire (somehow getting away with it) Oh, and god the noise, alternator load dumps, 100 volt spikes, -20V negative spikes, low cranking voltages. It's a fucking mess.

So - in your experience Luke, it doesn't let smaller amps hit a bit harder? Or keep lights from dimming on? I could see how on a competition system if would have less benefit, I just thought on an average e30 with a deck and a few amps(small stuff), it might give a noticeable boost to the things.

[darrenforeal]

Hmmm...well, lets see...your "disagree" versus my having installed well over 100 caps in cars with big systems, and not having seen much change...hmmmm.

I guess that whole "30 years of experience" and "professional" thing doesn't carry much weight compared to your "engineering student" thing, does it?

+1

Obviously...but the talk of how well they work to fire up a freezer or whatever is just retarded...way too many books, way too little time actually DOING stuff.

And just so you know, I got my first 'scope when I was 12.

That would be 1975. Long long ago, in a galaxy far away.

We used a better one as a tachometer (three phase self triggering) on our local slot car track (GP 12, 20, 27 and open class Wing cars) and found our ideal gearing with that knowledge.

I am well versed in theory too, but it is pointless and useless. George knows his shit, if he wanted that kind of info he would haver done his own research. Instead he specifically asked me to address the issue.

And George, just for that I am gonna burn this motherfucker DOWN!

oh yeah...I still like the pretty lights.

I too have done a lot of installs on high and low end systems with and without a cap. Granted not like Luke but still. Does it make a noticeable "real world" difference? NO. The end. But for god sakes if you must use one don't get a 1 farad one.

Also, I haven't been around this board that long but it is easy to tell Luke knows his shit backwards and forward. And theory and application are worlds apart in car audio.

[KennyT]

oh yeah...I still like the pretty lights.

At least that is what is important.

Give my fellow student time, eventually he will realize the books and classes he has paid for don't teach you much.

[StereoInstaller1]

Luke, what should theoretically happen is what he's mentioning. The real question is if they do anything.

Obviously...but the talk of how well they work to fire up a freezer or whatever is just retarded...way too many books, way too little time actually DOING stuff.

And just so you know, I got my first 'scope when I was 12.

That would be 1975. Long long ago, in a galaxy far away.

We used a better one as a tachometer (three phase self triggering) on our local slot car track (GP 12, 20, 27 and open class Wing cars) and found our ideal gearing with that knowledge.

I am well versed in theory too, but it is pointless and useless. George knows his shit, if he wanted that kind of info he would haver done his own research. Instead he specifically asked me to address the issue.

And George, just for that I am gonna burn this motherfucker DOWN!

oh yeah...I still like the pretty lights.