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  #41   Report Post  
MZ
 
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Default CAFacitor Myths (was " Capacitor, how to find out what size?")

While I agree with most of what you say to the lil' CAF feller here, there
are a couple of points that I feel the need to open my big mouth about...

And when that happens, the voltage drops to the 12v level of the
battery so that it can kick in the few extra amperes that the
alternator can't for those brief moments in time...


That's wrong, way wrong. Voltage plays no role in which componant
supplies current. The battery and alternator always share the total load
of the cars electrical system. When current demands exceed that of the
alternators output capability, the battery (which has many times the
reserve of any alternator) shoulders a greater share of the load.
Voltage doesn't make any difference - the voltage doesn't even need to
drop for this to occur.


But it DOES drop with increasing current draw. The alternator doesn't all
of a sudden max out at a particular current. The current delivered is
limited by the output impedance of the alternator which, although highly
nonlinear due to the feedback nature of the alternator output, causes a v
drop with increasing current draw. This of course is the nature of the
system's v drop. And the CAFer is partly right in saying the voltage will
approach that of the battery as the battery is required to deliver more
current due to the decrease in v output from the alt. Unfortunately, he
decided to oversimplify things a bit.


Your light bulbs dim simply because light bulbs are brighter on 14.4v
than they are on 12v... that's not a sign of a charging problem.


Again, you ignore current. I'd like to see you light a household light
bulb with 10 AA batteries, and see how bright it gets. The dimming is
because of a lack of current. The dropoff in voltage is a symptom, not a
cause.


When you hook up those 10 AA batteries to the bulb, a current will flow.
This current will cause a v drop across the battery's effective output Z
such that the voltage at the terminal of the battery array will no longer be
15v. Ohm's law tells us that v and i are non-separable (except at the
asymptotes, I suppose).


The capacitor smooths the transition from alternator to battery,


There is no "transition".


Thank you. This needed to be pointed out. I don't know whether he's
oversimplifying here or if he truly believes the battery turns on and off
its current delivery.

quite
dramatically even.. the results can be seen in greatly reduced
headlight dimming, as there's a nice [relatively] slow transition down
to 12v now, rather than a temporary, sudden slam to even below 12v
every time there is a large transient peak.


This may come as a newsflash, but there are capacitors built into
amplifier power supplies, and generally they supply sufficient charge
for normal operation.


Yeah, but they're not good enough. Engineers don't know how to build their
own equipment, right?

Also, there is a lag time for caps too, and it is a function of the load
across the capacitors terminals. That is why manufacturers recommend you
locate the caps closest to the amps.


I have no idea why they recommend this. It can be demonstrated using ohm's
law that placing the caps as close to the headlights (or ECM, or whatever
device is exhibiting the symptom), and thereby lowering the ESL/ESR to the
symptomatic device, reduces the dimming/fluctuation.


  #42   Report Post  
Scott Gardner
 
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Default Capacitor, how to find out what size?

On Tue, 16 Mar 2004 19:10:04 -0500, thelizman
wrote:

Tha Ghee wrote:

if your batt. is weak which most times it is,


You're average car battery can put out more power than half a dozen
alternators.

--
thelizman "I didn't steal the FAQ either"


I think the point Ghee was trying to make was that as a battery gets
old and tired, its ESR increases, causing a larger voltage drop for a
given current draw, even if the associated wiring is clean and of a
proper gauge.

I've seen installations where dimming/flickering lights were solved by
replacing a five-year-old tired stock battery with a new, lower-ESR
battery. The new battery had a significantly lower ESR, both by
design and by virtue of the fact that it was new. The battery swap
was done after upgrading the power and ground leads under the hood, of
course.

Scott Gardner
  #43   Report Post  
MZ
 
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Default Capacitor, how to find out what size?

I think the point Ghee was trying to make was that as a battery gets
old and tired, its ESR increases, causing a larger voltage drop for a
given current draw, even if the associated wiring is clean and of a
proper gauge.

I've seen installations where dimming/flickering lights were solved by
replacing a five-year-old tired stock battery with a new, lower-ESR
battery. The new battery had a significantly lower ESR, both by
design and by virtue of the fact that it was new. The battery swap
was done after upgrading the power and ground leads under the hood, of
course.


People aren't replacing their batteries on a regular basis anyway?


  #44   Report Post  
Scott Gardner
 
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Default Capacitor, how to find out what size?

On Wed, 17 Mar 2004 18:01:03 -0500, "MZ"
wrote:

I think the point Ghee was trying to make was that as a battery gets
old and tired, its ESR increases, causing a larger voltage drop for a
given current draw, even if the associated wiring is clean and of a
proper gauge.

I've seen installations where dimming/flickering lights were solved by
replacing a five-year-old tired stock battery with a new, lower-ESR
battery. The new battery had a significantly lower ESR, both by
design and by virtue of the fact that it was new. The battery swap
was done after upgrading the power and ground leads under the hood, of
course.


People aren't replacing their batteries on a regular basis anyway?


Many people delay replacing their batteries until their car doesn't
start. It should be a routine maintenance item, but some people just
assume everything is fine until a problem crops up. It also doesn't
help that battery life varies so widely. In Texas, I felt I was doing
good to get three years out of a battery. In a more mild climate,
I've gotten significantly longer use out of batteries.

Scott Gardner
  #45   Report Post  
thelizman
 
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Default CAFacitor Myths (was " Capacitor, how to find out what size?")

MZ wrote:

But it DOES drop with increasing current draw.


Right, but gouleboys contention was that voltage was drawn down to a
certain point at which time the battery "kicked in". The voltage drop is
a symptom of current drain.

When you hook up those 10 AA batteries to the bulb, a current will flow.
This current will cause a v drop across the battery's effective output Z
such that the voltage at the terminal of the battery array will no longer be
15v. Ohm's law tells us that v and i are non-separable (except at the
asymptotes, I suppose).


The phenomenon you describe is Kirchoff's law (sum of voltage drops =
applied voltage); thanks for plugging ohms law. And yes, while current
and voltage are inseparable, this does not affect the fact that overall
power is a function of voltage AND current. Thats why light bulbs are
rated in watts, not volts (that and the voltage is assumed). Gouleboy
contends that lights dim because of voltage drops, and disregards
available current.

I have no idea why they recommend this. It can be demonstrated using ohm's
law that placing the caps as close to the headlights (or ECM, or whatever
device is exhibiting the symptom), and thereby lowering the ESL/ESR to the
symptomatic device, reduces the dimming/fluctuation.


That's if the idea of the cap is to reduce light dimming. Its not. It's
to act as a secondary reserve for your amps. Of course, in an otherwise
healthy electrical system with large gauge power wires, it wouldn't
matter where you stuffed the amp.

--
thelizman "I didn't steal the FAQ either"

Before you ask a question, check the FAQs for this newsgroup at
http://www.mobileaudio.com/rac-faq. It contains over a decade and
a half of knowledge.

teamROCS Car Audio Forums http://www.teamrocs.com/caraudio/
teamROCS Car Audio News http://www.teamrocs.com/news/
"It's about the music, stupid"

This post is Copyright (C) 2004. Reproduction of its content anywhere
other than usenet without the express written permission of the author
is forbidden.


  #46   Report Post  
thelizman
 
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Default Capacitor, how to find out what size?

Scott Gardner wrote:

I think the point Ghee was trying to make was


How can you be sure what Ghee was trying to say, he no speaka engrish!

I have to take him literally, and when he states that a battery is
weaker than an alternator, I have to correct him.

--
thelizman "I didn't steal the FAQ either"

Before you ask a question, check the FAQs for this newsgroup at
http://www.mobileaudio.com/rac-faq. It contains over a decade and
a half of knowledge.

teamROCS Car Audio Forums http://www.teamrocs.com/caraudio/
teamROCS Car Audio News http://www.teamrocs.com/news/
"It's about the music, stupid"

This post is Copyright (C) 2004. Reproduction of its content anywhere
other than usenet without the express written permission of the author
is forbidden.
  #47   Report Post  
MZ
 
Posts: n/a
Default CAFacitor Myths (was " Capacitor, how to find out what size?")

When you hook up those 10 AA batteries to the bulb, a current will flow.
This current will cause a v drop across the battery's effective output Z
such that the voltage at the terminal of the battery array will no

longer be
15v. Ohm's law tells us that v and i are non-separable (except at the
asymptotes, I suppose).


The phenomenon you describe is Kirchoff's law (sum of voltage drops =
applied voltage); thanks for plugging ohms law.


No, actually I was referring to ohm's law. I guess I just wasn't clear. I
was trying to point out that since the resistances are constant (well, to a
good approximation, under steady state conditions at least; a bulb's
resistance otherwise is anything but constant!), the voltage drop across the
effective output Z is a direct result of the current drawn.

I have no idea why they recommend this. It can be demonstrated using

ohm's
law that placing the caps as close to the headlights (or ECM, or

whatever
device is exhibiting the symptom), and thereby lowering the ESL/ESR to

the
symptomatic device, reduces the dimming/fluctuation.


That's if the idea of the cap is to reduce light dimming. Its not. It's
to act as a secondary reserve for your amps. Of course, in an otherwise
healthy electrical system with large gauge power wires, it wouldn't
matter where you stuffed the amp.


Yeah, but that notion is foolish. What do the amps need it for? They're
not the devices that are exhibiting the symptom. People buy caps because
their lights are dimming (or, more likely, because a salesman convinced them
of it, but that's another matter). So if their lights are dimming, then
they'll most effectively reduce that symptom by installing the cap as
electrically close to the headlights as possible. Manufacturers are being
disingenuous by telling people to go out of their way to mount it close to
the amps. I'm presuming they give this suggestion to maintain the facade
that caps improve bass output or some such nonsense.

In the end, I tell people to mount it wherever it's prettiest if they insist
on adding a cap. I think Eddie coined the term "jewelry caps". Fitting...


  #48   Report Post  
Scott Gardner
 
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Default Capacitor, how to find out what size?

On Thu, 18 Mar 2004 00:14:00 -0500, thelizman
wrote:

Scott Gardner wrote:

I think the point Ghee was trying to make was


How can you be sure what Ghee was trying to say, he no speaka engrish!

I have to take him literally, and when he states that a battery is
weaker than an alternator, I have to correct him.

--
thelizman "I didn't steal the FAQ either"


Okay, except that's not what he was saying. You posted the following
paragraph:


That's why cars have batteries. If you have flicker at idle, it's
because your power and ground wires at the battery and alternator are
insufficient are insufficient.

--

Ghee responded with this:


if your batt. is weak which most times it is, it doesn't matter, what the
alt or wires are like. if your going with a aftermarket alt. it may not
work any better.




He never compared a battery to an alternator, or claimed the battery
was weaker. He simply brought up the point that with a weak battery,
you can still get flickering or dimming at idle, even with a healthy
alternator and good wires, and if this is the case, an aftermarket
alternator might not improve the situation.

His English seems pretty good to me...

Scott Gardner




  #49   Report Post  
Tha Ghee
 
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"thelizman" wrote in message
...
Tha Ghee wrote:

if your batt. is weak which most times it is,


You're average car battery can put out more power than half a dozen
alternators.

--
thelizman "I didn't steal the FAQ either"


batteries don't put out power the store it, so how can they put out so
much??


  #50   Report Post  
Tha Ghee
 
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Default Capacitor, how to find out what size?

"MZ" wrote in message
...
I think the point Ghee was trying to make was that as a battery gets
old and tired, its ESR increases, causing a larger voltage drop for a
given current draw, even if the associated wiring is clean and of a
proper gauge.

I've seen installations where dimming/flickering lights were solved by
replacing a five-year-old tired stock battery with a new, lower-ESR
battery. The new battery had a significantly lower ESR, both by
design and by virtue of the fact that it was new. The battery swap
was done after upgrading the power and ground leads under the hood, of
course.


People aren't replacing their batteries on a regular basis anyway?

they should be especially in the Midwest, about every three years but most
don't.




  #51   Report Post  
Tha Ghee
 
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Default Capacitor, how to find out what size?

"thelizman" wrote in message
...
Tha Ghee wrote:


how can there be ripples in DC voltage??


...proof that there is such a thing as a "stupid question".


no there isn't just silly and cranky, people like the Liz.


  #52   Report Post  
Tha Ghee
 
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"thelizman" wrote in message
...
Scott Gardner wrote:

I think the point Ghee was trying to make was


How can you be sure what Ghee was trying to say, he no speaka engrish!

I have to take him literally, and when he states that a battery is
weaker than an alternator, I have to correct him.

but you didn't correct me, you were wrong and I showed you the errors in
your ways, don't be mad because Scott called you out.


  #53   Report Post  
Tha Ghee
 
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Default Capacitor, how to find out what size?

"Scott Gardner" wrote in message
...
On Thu, 18 Mar 2004 00:14:00 -0500, thelizman
wrote:

Scott Gardner wrote:

I think the point Ghee was trying to make was


How can you be sure what Ghee was trying to say, he no speaka engrish!

I have to take him literally, and when he states that a battery is
weaker than an alternator, I have to correct him.

--
thelizman "I didn't steal the FAQ either"


Okay, except that's not what he was saying. You posted the following
paragraph:


That's why cars have batteries. If you have flicker at idle, it's
because your power and ground wires at the battery and alternator are
insufficient are insufficient.

--

Ghee responded with this:


if your batt. is weak which most times it is, it doesn't matter, what the
alt or wires are like. if your going with a aftermarket alt. it may not
work any better.




He never compared a battery to an alternator, or claimed the battery
was weaker. He simply brought up the point that with a weak battery,
you can still get flickering or dimming at idle, even with a healthy
alternator and good wires, and if this is the case, an aftermarket
alternator might not improve the situation.

His English seems pretty good to me...

Scott Gardner

thank you Scott, the Liz has some nerve with all the drivel he spews. he
may intimidate a nooB but not me, ow well Liz go to CAF and fell like a big
man again.


  #54   Report Post  
Tha Ghee
 
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"thelizman" wrote in message
...
Tha Ghee wrote:

no Mark is correct here, the fluctuation is greatest at startup of the

car
and audio system.


You don't read engrish very well do you?

this is why most things break when you turn them off,
like light bulbs.


Light bulbs break when you turn them on. They break because over time
the filament loses mass as it is vapor deposited on the cool surface of
the inside of the bulb. When enough material vaporizes, the filament can
no longer handle the current passing through it.

they also break when there's to much current going through the circuit, but
you left that part out in your infinite wisdom.


  #55   Report Post  
thelizman
 
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Default Capacitor, how to find out what size?

Tha Ghee wrote:

but you didn't correct me, you were wrong and I showed you the errors in
your ways,


You're an idiot.

Lets take a battery rated at 550 cca. It can put out about 6,600 watts
of power for 30 seconds before it starts to lose strength, and that's at
0 degrees celcius.

Take a so-called "high power" alternator rated at 100 amps. At engine
idle, it is only capable of about 1,440 watts of power for 30 seconds.
If the engine isn't running, it puts out squat.

I think it's rather obvious that a battery can produce more power than
an alternator.

--
thelizman "I didn't steal the FAQ either"

Before you ask a question, check the FAQs for this newsgroup at
http://www.mobileaudio.com/rac-faq. It contains over a decade and
a half of knowledge.

teamROCS Car Audio Forums http://www.teamrocs.com/caraudio/
teamROCS Car Audio News http://www.teamrocs.com/news/
"It's about the music, stupid"

This post is Copyright (C) 2004. Reproduction of its content anywhere
other than usenet without the express written permission of the author
is forbidden.


  #56   Report Post  
thelizman
 
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Default Capacitor, how to find out what size?

Tha Ghee wrote:

thank you Scott, the Liz has some nerve with all the drivel he spews. he
may intimidate a nooB but not me


What are you talking about? You ARE a noob. And only semi-literate.

--
thelizman "I didn't steal the FAQ either"

Before you ask a question, check the FAQs for this newsgroup at
http://www.mobileaudio.com/rac-faq. It contains over a decade and
a half of knowledge.

teamROCS Car Audio Forums http://www.teamrocs.com/caraudio/
teamROCS Car Audio News http://www.teamrocs.com/news/
"It's about the music, stupid"

This post is Copyright (C) 2004. Reproduction of its content anywhere
other than usenet without the express written permission of the author
is forbidden.
  #57   Report Post  
thelizman
 
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Tha Ghee wrote:
"thelizman" wrote in message
...

Light bulbs break when you turn them on. They break because over time
the filament loses mass as it is vapor deposited on the cool surface of
the inside of the bulb. When enough material vaporizes, the filament can
no longer handle the current passing through it.


they also break when there's to much current going through the circuit, but
you left that part out in your infinite wisdom.


What part of "the filament can NO LONGER HANDLE THE CURRENT PASSING
THROUGH IT" escaped your comprehension, smacktard?


--
thelizman "I didn't steal the FAQ either"

Before you ask a question, check the FAQs for this newsgroup at
http://www.mobileaudio.com/rac-faq. It contains over a decade and
a half of knowledge.

teamROCS Car Audio Forums http://www.teamrocs.com/caraudio/
teamROCS Car Audio News http://www.teamrocs.com/news/
"It's about the music, stupid"

This post is Copyright (C) 2004. Reproduction of its content anywhere
other than usenet without the express written permission of the author
is forbidden.
  #58   Report Post  
Tony Hwang
 
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Default Capacitor, how to find out what size?

Tha Ghee wrote:
"thelizman" wrote in message
...

Tha Ghee wrote:

no Mark is correct here, the fluctuation is greatest at startup of the


car

and audio system.


You don't read engrish very well do you?


this is why most things break when you turn them off,
like light bulbs.


Light bulbs break when you turn them on. They break because over time
the filament loses mass as it is vapor deposited on the cool surface of
the inside of the bulb. When enough material vaporizes, the filament can
no longer handle the current passing through it.


they also break when there's to much current going through the circuit, but
you left that part out in your infinite wisdom.


Hi,
Most electrical load is inductive by nature. So in rush current when
turned on is lot more than normal running current. Like if a motor draws
10 Amp when running, it can draw even 30 Amp for short moment when
turned on, starts spinning.
Tony
  #59   Report Post  
MZ
 
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Default Capacitor, how to find out what size?

Hi,
Most electrical load is inductive by nature. So in rush current when
turned on is lot more than normal running current. Like if a motor draws
10 Amp when running, it can draw even 30 Amp for short moment when
turned on, starts spinning.


This has little to do with inductance. In the case of the light bulb, the
initial current is greater because of the temperature dependence of
resistivity for tungsten. A cold tungsten filament has a very low
resistance.


  #60   Report Post  
geolemon
 
Posts: n/a
Default CAFacitor Myths (was " Capacitor, how to find out what size?")

For a guy with such a big mouth, you really are ignorant to the ver
fundamentals of how a car electrical system works.
I -seriously- am shocked!
thelizman wrote:
*geolemon wrote:

ONLY if the -average- current draw exceeds your alternator's
capabilities do you have a -charging- problem...


That's oversimplified - and wrong. If the cables are corroded, the
biggest alternator in the world won't charge. If the connections are
corroded, the same. *

No one mentioned corrosion here.. if there's corrosion, that's
separate issue.
Your argument is like saying the geometry of your car's suspensio
doesn't matter, because you might get a flat tire.
*
Even smallish amplifiers can yield peak current demands which will
exceed even a large alternator's supply capabilities...


"Peak" does not equal "average". Even a large amplifier - on averag
-
doesn't drain more than a couple of amps of current, and transients
"peaks" only last a fraction of a second. These peak current draw
are
buffered by the amplifiers internal capacitor banks, and recharg
demand
is handled by the cars battery, because alternators simply don'
react
fast enough.
*

Exactly my point, with regard to the difference between "peaks" an
"average" current draw.
That's as I spelled it out.

And yes, capacitors that are on the rail-voltage side of the powe
supply are much more efficient - particularly the higher in impedanc
you go on the load side of the alternator.
More efficient, in terms of "stiffening" the amplifier's ability t
supply the output that it's supposed to.

Break that mindset.
I'm not talking about what a capacitor does to the output of a
amplifier. That's not relevant in the scope of my post at all.

I'm discussing the load that the amplifier places on your car'
electircal system... and simply that.
I'm discussing what happens when you exceed the current supply of th
alternator:

And when that happens, the voltage drops to the 12v level of the
battery so that it can kick in the few extra amperes that the
alternator can't for those brief moments in time...


That's wrong, way wrong. Voltage plays no role in which componant
supplies current. The battery and alternator always share the tota
load
of the cars electrical system. When current demands exceed that o
the
alternators output capability, the battery (which has many times the
reserve of any alternator) shoulders a greater share of the load.
Voltage doesn't make any difference - the voltage doesn't even nee
to
drop for this to occur.

The battery and alternator do share the load, that's my point.
As long as your average current draw (not peak!) is lower than th
average current output supply capability of the alternator (factorin
RPM and all that), then you will not have discharged your battery ove
the duration of that usage.
All is healthy... despite the fact that you might have had severa
light-dimming "holy cow" current draw moments, maybe even exceedin
175a!

Here's a scenario for you:
During an hour-long listening session, let's say my average curren
draw was around 15a...
During that time, I had two transient peaks that reached a huge 150a i
terms of current demand on my electrical system.
Are you advocating, that because my alternator is say, only an 80
alternator... that warrants my replacing my alternator?

What I am saying is that's ludicrous thinking.
Until you have a charging problem, replacing the alternator doesn'
make sense.
And until your -average- current draw becomes excessive - relative t
the capabilities of your stock alternator - you shouldn't replace it.


There -are- downsides to aftermarket alternators, whether you choose t
believe that or not (that's a personal problem). It can be measured..
in more ways than just the pocketbook.


The capacitor smooths the transition from alternator to battery,

There is no "transition".
Let me get this straight..
You actually are stating that the voltage will not fall when th
alternator's current capabilities are exceeded?
You are stating that the load on the battery does not rise, the
battery is not the thing "picking up the slack", supplying the
current that the alternator cannot?

In other words... let's for example assume at a given RPM an
alternator is able to supply 100a of current, at a 14.4v level.
Let's say you start to draw 150a.
Are you trying to claim that the voltage will not drop to the 12v
level of the battery, when this happens?

This is a very simple test that you can do with a voltmeter, if you
don't have one installed in your dashboard. Easy to do, with a CD of
test tones, and your volume knob, if you have an amp that's capable
of drawing those current levels.



Your light bulbs dim simply because light bulbs are brighter on

14.4v
than they are on 12v... that's not a sign of a charging problem.


Again, you ignore current. I'd like to see you light a household
light
bulb with 10 AA batteries, and see how bright it gets. The dimming
is
because of a lack of current. The dropoff in voltage is a symptom,
not a
cause.

No...
The light bulbs getting dimmer is a symptom of the voltage dropping.
The voltage dropping is a symptom of something else... the current
capabilities of the alternator being temporarily exceeded.

Two unrelated things...
But people "believe" that they are buying a capacitor to help light
dimming.
In actuality, they are buying a shock-absorber for their electrical
system... and a nice side effect is that headlight dimming is
reduced.

I suppose you believe headlight dimming is just as dramatic without a
capacitor as with?



quite
dramatically even.. the results can be seen in greatly reduced
headlight dimming, as there's a nice [relatively] slow transition

down
to 12v now, rather than a temporary, sudden slam to even below 12v
every time there is a large transient peak.


This may come as a newsflash, but there are capacitors built into
amplifier power supplies, and generally they supply sufficient charge
for normal operation.

Yes, capacitors are much more efficient on the rail voltage side of the
power supply than the supply voltage side.
Sufficient charge?

Remember, we aren't talking about the performance of the amp... I'm
talking about the demand on the electrical system that the amp places.
If your amplifier is demanding 150a for a transient peak... is that a
sign that the amplifier has enough internal capacitance? ;-)

That being said, we must now be concerned for what happens, when the
amp does demand 150a from your electrical system.
That's the point, and that's when I say the capacitor can behave like a
shock absorber, because the battery WILL be suddenly called heavily
into play to provide that which the alternator can't.
Voltage will drop, and the moment voltage drops, the capacitor begins
discharging, helping supply, until the battery is providing enough
current where the alternator and battery are equalized again, supply
meeting demand.
--
geolemon
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  #61   Report Post  
geolemon
 
Posts: n/a
Default CAFacitor Myths (was " Capacitor, how to find out what size?")

Also, there is a lag time for caps too, and it is a function of th
load
across the capacitors terminals. That is why manufacturers recommen
you
locate the caps closest to the amps.

The amount of charge stored in a capacitor is huge. There's a reaso
the
directions advise you to charge the cap through a resistor with the
engine running. You're not going to drain a 1 or 1/2 farad cap s
that
it can't deliver at least 12 volts with a car audio system.
Yes, there's some ESR in a cap, that does create some lag time.
But, bear in mind, this takes the capacitor down from being
"theoretically instantanious" device, to a "realistically just almos
instantanious" device.
Contrast that to a battery, whose transient response is inherentl
slow. Slow not only to charge, but to discharge as well.
And the transient response of a deep-cycle battery is inherentl
slower.. an intentional design trade-off, in using thicker, mor
warp-resistant plates in the battery. Takes abuse.. but doesn'
transfer the electrons as fast.
The rise time of a capacitor may as well be the "theoretica
instantanious", compared to the slow milliseconds it takes for
battery to respond.

Transient response of a battery compared to the transient response of
capacitor.

Yes, the charge stored in a capacitor is huge...
But we are only concerned with the amount of charge relative to a dro
from 14.4v down to 12v, the lowest a capacitor will discharge to in
car... how much current it can provide as it drops between those tw
voltages.
*

Another downside on an alternator (besides the high expense,
possibility of it being largely ineffective without setting you

idle
speed north of 2000RPM,


There's no need to idle up. A quality alternator is rated for outpu
at
idle. Otherwise, you can just slap a larger pulley on th
alternator.
*That's been shown not to be true, quite often.

RPM does affect current capability, and often the ratings are taken a
higher RPM's. Do your homework before buying - I'm not the only one t
suggest that for alternators.
[b]

and installation considerations that have been
mentioned) is the fact that a bigger alternator is a bigger dra

on
your engine... and it's a bigger drag all the time, not just whe

you
need it.


Wrong. An alternator only requires more torque when the demand place
on
it increases.
[b]

Yes, the electromagnetic forces will increase, increasing drag.
but there's a no-load increase in drag as well. The upgrade
alternator is larger than the non-upgraded unit... not necessaril
in terms of chassis dimensions...
A larger alternator is more difficult to spin, inherently.
Bigger
rotor, larger magnetic forces... they can really impact you
car's
performance, robbing horsepower.

Most aftermarket alternators are no larger in size than thei
stock
componants. The difference is in the number of turns in the coil
and
the increase in mass of the windings in negligable.
...but -especially- if chassis dimensions are unchanged, thi
forces the increases to be inherently in the windings. Mor
windings, more mass.
*You are full of information. MIS information.*

The problem with RAC is largely people like yourself... and onc
again, I point out that's likely why RAC popularity is declining
not growing.

It's not me who's spreading misinformation, it's people lik
yourself that believe if you bellow loudly enough, people wil
believe what you are saying.
This isn't Field of Dreams...
"If I say it..."

What's most disturbing to me, personally, is the inconsiderat
behavior. The rude attitude. The "F-you, get lost". The "If
didn't say it, shut the hell up.. no one can talk here but me
attitude.
That's based on observation, btw.

You know the old saying...
If a tree falls in the forest, and no one is around to hear it, di
it really fall?

Similarly...
If you say something... and no one disputes it, because they've
encountered immature little fits of beliggerant misunderstandings
in the past... does that make it right?

--
geolemon
------------------------------------------------------------------------
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  #62   Report Post  
thylantyr
 
Posts: n/a
Default CAFacitor Myths (was " Capacitor, how to find out what size?")

--CAFacitor Myths

What are you folks doing? grabbing individual thoughts posted
on CAF and assuming that is what everyone believes ?

I've debated with Geo about capacitors, a fun debate actually,
there is no hard feelings. In fact, we still discuss other issues,
we may or may not agree.

The point is, you will find discontinuity on every forum
regarding any issue and you shouldn't judge the whole forum.

If you want to discuss certain issues that were posted, then
a more appropriate thread title would be better.

/heh
-
thylanty
-----------------------------------------------------------------------
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  #63   Report Post  
geolemon
 
Posts: n/a
Default CAFacitor Myths (was " Capacitor, how to find out what size?")

thylantyr wrote:
*--CAFacitor Myths

What are you folks doing? grabbing individual thoughts posted
on CAF and assuming that is what everyone believes ?

I've debated with Geo about capacitors, a fun debate actually,
there is no hard feelings. In fact, we still discuss other issues,
we may or may not agree.

The point is, you will find discontinuity on every forum
regarding any issue and you shouldn't judge the whole forum.

If you want to discuss certain issues that were posted, then
a more appropriate thread title would be better.

/hehe *

I think more important to note, the maturity level is higher at CA
than RAC, with regard to discussions.

When Thy and I get into arguements - they aren't arguements.

There's a relative ease in being able to separate that which i
objective - which we end up agreeing on in the end - from that which i
a matter of opinion - which we respect each other's opinion on...
without the immature displays of aggression, without elementary-schoo
tossing about of personal insults - that have nothing to do with th
topic at-hand - but you certainly find that on RAC.

And I don't mean to generalize about RAC... there are some good member
who have taken insult when I've said something similar in the past..
to them, I clarify.

But there is a certain loudmouthed core of a few members that delud
themselves to be "the ruling party" that do behave in this manner, an
it simply prevents actual communication - as it does in all mediums
including spoken word.

I think it's a shame (obviously others do as well) - but in the end, i
is of no consequence to me, because I've been discouraged from visitin
RAC already, by the members...
I feel much more confident in the longetivity of the places that I hav
commited to use as objective resources
-
geolemo
-----------------------------------------------------------------------
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  #64   Report Post  
Kevin Murray
 
Posts: n/a
Default Capacitor, how to find out what size?

The inductive component of a load will limit the in-rush current, not enhance
it. You might be thinking of the stray capacitance of a circuit which tends to
cause high power-up currents.

A light bulb has a very low inductance. It has a high "instant-on" current
because it's resistance varies with temperature. As the filament heats up the
resistance rises and the current drops. In the case of electric motors, the
in-rush current occurs because the field is not yet present. Once the field is
established and the motor starts doing work, the current varies with the load on
the motor.



"Tony Hwang" wrote in message
news:s147c.866493$X%5.244200@pd7tw2no...
Tha Ghee wrote:
"thelizman" wrote in message
...

Tha Ghee wrote:

no Mark is correct here, the fluctuation is greatest at startup of the


car

and audio system.

You don't read engrish very well do you?


this is why most things break when you turn them off,
like light bulbs.

Light bulbs break when you turn them on. They break because over time
the filament loses mass as it is vapor deposited on the cool surface of
the inside of the bulb. When enough material vaporizes, the filament can
no longer handle the current passing through it.


they also break when there's to much current going through the circuit, but
you left that part out in your infinite wisdom.


Hi,
Most electrical load is inductive by nature. So in rush current when
turned on is lot more than normal running current. Like if a motor draws
10 Amp when running, it can draw even 30 Amp for short moment when
turned on, starts spinning.
Tony



  #65   Report Post  
gregs
 
Posts: n/a
Default CAFacitor Myths (was " Capacitor, how to find out what size?")

In article m, geolemon wrote:
Also, there is a lag time for caps too, and it is a function of the
load
across the capacitors terminals. That is why manufacturers recommend
you
locate the caps closest to the amps.

The amount of charge stored in a capacitor is huge. There's a reason
the
directions advise you to charge the cap through a resistor with the
engine running. You're not going to drain a 1 or 1/2 farad cap so
that
it can't deliver at least 12 volts with a car audio system.
Yes, there's some ESR in a cap, that does create some lag time.

But, bear in mind, this takes the capacitor down from being a
"theoretically instantanious" device, to a "realistically just almost
instantanious" device.
Contrast that to a battery, whose transient response is inherently
slow. Slow not only to charge, but to discharge as well.
And the transient response of a deep-cycle battery is inherently
slower.. an intentional design trade-off, in using thicker, more
warp-resistant plates in the battery. Takes abuse.. but doesn't
transfer the electrons as fast.
The rise time of a capacitor may as well be the "theoretical
instantanious", compared to the slow milliseconds it takes for a
battery to respond.


The only time lag for a battery to respond that I know of it
its temperature. When it get warm with current draw, its
able to produce more current.


Transient response of a battery compared to the transient response of a
capacitor.

Yes, the charge stored in a capacitor is huge...
But we are only concerned with the amount of charge relative to a drop
from 14.4v down to 12v, the lowest a capacitor will discharge to in a
car... how much current it can provide as it drops between those two
voltages.
*

Another downside on an alternator (besides the high expense,
possibility of it being largely ineffective without setting your

idle
speed north of 2000RPM,


There's no need to idle up. A quality alternator is rated for output
at
idle. Otherwise, you can just slap a larger pulley on the
alternator.


No, most need at least 1500 RPM.


*That's been shown not to be true, quite often.

RPM does affect current capability, and often the ratings are taken at
higher RPM's. Do your homework before buying - I'm not the only one to
suggest that for alternators.
[b]

and installation considerations that have been
mentioned) is the fact that a bigger alternator is a bigger drag

on
your engine... and it's a bigger drag all the time, not just when

you
need it.


Mostly false. I loads with current draw.

Wrong. An alternator only requires more torque when the demand placed
on
it increases.
[b]
Yes, the electromagnetic forces will increase, increasing drag..
but there's a no-load increase in drag as well. The upgraded
alternator is larger than the non-upgraded unit... not necessarily
in terms of chassis dimensions... [b]
A larger alternator is more difficult to spin, inherently.
Bigger
rotor, larger magnetic forces... they can really impact your
car's
performance, robbing horsepower.

Most aftermarket alternators are no larger in size than their
stock
componants. The difference is in the number of turns in the coil,
and


There seems to be some more misinformation about current draws. The alternator
provides virtually all current untill the voltage gets down to below 13 volts at which time the
battery starts pulling. It does not really begin to draw significant current untill it gets
in the mid 12.5 volts range. At high current such as with starting currents, it dips well
below 12 volts.


  #67   Report Post  
MZ
 
Posts: n/a
Default CAFacitor Myths (was " Capacitor, how to find out what size?")

There seems to be some more misinformation about current draws. The
alternator
provides virtually all current untill the voltage gets down to below 13

volts at which time the
battery starts pulling.


Which is, in effect, all the time. Ever run an audio system off an
alternator without a battery connected? (don't try this at home)


  #68   Report Post  
thelizman
 
Posts: n/a
Default CAFacitor Myths (was " Capacitor, how to find out what size?")

thylantyr wrote:

What are you folks doing? grabbing individual thoughts posted
on CAF and assuming that is what everyone believes ?


This is not CAF. This is rec.audio.car.

--
thelizman "I didn't steal the FAQ either"

Before you ask a question, check the FAQs for this newsgroup at
http://www.mobileaudio.com/rac-faq. It contains over a decade and
a half of knowledge.

teamROCS Car Audio Forums http://www.teamrocs.com/caraudio/
teamROCS Car Audio News http://www.teamrocs.com/news/
"It's about the music, stupid"

This post is Copyright (C) 2004. Reproduction of its content anywhere
other than usenet without the express written permission of the author
is forbidden.
  #69   Report Post  
thelizman
 
Posts: n/a
Default Capacitor, how to find out what size?

MZ wrote:
Hi,
Most electrical load is inductive by nature. So in rush current when
turned on is lot more than normal running current. Like if a motor draws
10 Amp when running, it can draw even 30 Amp for short moment when
turned on, starts spinning.



This has little to do with inductance. In the case of the light bulb, the
initial current is greater because of the temperature dependence of
resistivity for tungsten. A cold tungsten filament has a very low
resistance.


And in the case of electrical motors, the surge in current has to do
with the low impedance of the motors coil at startup.

--
thelizman "I didn't steal the FAQ either"

Before you ask a question, check the FAQs for this newsgroup at
http://www.mobileaudio.com/rac-faq. It contains over a decade and
a half of knowledge.

teamROCS Car Audio Forums http://www.teamrocs.com/caraudio/
teamROCS Car Audio News http://www.teamrocs.com/news/
"It's about the music, stupid"

This post is Copyright (C) 2004. Reproduction of its content anywhere
other than usenet without the express written permission of the author
is forbidden.
  #70   Report Post  
Tha Ghee
 
Posts: n/a
Default Capacitor, how to find out what size?

"thelizman" wrote in message
...
Tha Ghee wrote:

thank you Scott, the Liz has some nerve with all the drivel he spews.

he
may intimidate a nooB but not me


What are you talking about? You ARE a noob. And only semi-literate.

--

not at all, I may not be an old cranky installer like you but I'm far from a
nooB, and it's grammar not reading skills. but I know you wouldn't
understand that.




  #71   Report Post  
Tha Ghee
 
Posts: n/a
Default Capacitor, how to find out what size?

"thelizman" wrote in message
...
Tha Ghee wrote:

but you didn't correct me, you were wrong and I showed you the errors in
your ways,


You're an idiot.

Lets take a battery rated at 550 cca. It can put out about 6,600 watts
of power for 30 seconds before it starts to lose strength, and that's at
0 degrees celcius.

Take a so-called "high power" alternator rated at 100 amps. At engine
idle, it is only capable of about 1,440 watts of power for 30 seconds.
If the engine isn't running, it puts out squat.

I think it's rather obvious that a battery can produce more power than
an alternator.

not at all, don't be upset since people are calling you out and you shown to
be nothing more than a cranky old man that has no social life so you pick on
people on the net to make yourself feel better, this is sad.

what batt. can produce 6,600 watts show me some graphs, but you'll doctor
them up like you did with TN.


  #72   Report Post  
Tha Ghee
 
Posts: n/a
Default Capacitor, how to find out what size?

"thelizman" wrote in message
...
Tha Ghee wrote:
"thelizman" wrote in message
...

Light bulbs break when you turn them on. They break because over time
the filament loses mass as it is vapor deposited on the cool surface of
the inside of the bulb. When enough material vaporizes, the filament can
no longer handle the current passing through it.


they also break when there's to much current going through the circuit,

but
you left that part out in your infinite wisdom.


What part of "the filament can NO LONGER HANDLE THE CURRENT PASSING

THROUGH IT" escaped your comprehension, smacktard?

so in fact you just proved my point, that was the whole point of the post,
to show that you were incorrect and I wasn't. do you hate that I keep
showing you up in your only place of refuge??


  #73   Report Post  
Tha Ghee
 
Posts: n/a
Default Capacitor, how to find out what size?

"Tony Hwang" wrote in message
news:s147c.866493$X%5.244200@pd7tw2no...
Tha Ghee wrote:
"thelizman" wrote in message
...


Hi,
Most electrical load is inductive by nature. So in rush current when
turned on is lot more than normal running current. Like if a motor draws
10 Amp when running, it can draw even 30 Amp for short moment when
turned on, starts spinning.
Tony


that makes sense


  #74   Report Post  
Daniel Snooks
 
Posts: n/a
Default Capacitor, how to find out what size?

Notice that in the first response here, Tha Ghee asserts that most things
break when you turn them OFF. I hope he meant to say ON, or none of it makes
any sense whatsoever.
More importantly, in the final response by Tha Ghee, he states that the
whole point of the post was to show that thelizard was incorrect. Um, he
never showed that. On a side note ... what does a lightbulb filament have to
do with the price of escargot in Spain? IF I read this thread correctly, the
discussion is (once again) what to do about capacitors. Are they useful? if
so in what application, if not ... why not?

Don't think that I feel thelizard needs a hand, just putting in my $0.02

Dan Snooks

Tha Ghee wrote
this is why most things break when you turn them off,
like light bulbs.


thelizman wrote
Light bulbs break when you turn them on. They break because over time
the filament loses mass as it is vapor deposited on the cool surface of
the inside of the bulb. When enough material vaporizes, the filament can
no longer handle the current passing through it.


Tha Ghee wrote
they also break when there's to much current going through the circuit,
but you left that part out in your infinite wisdom.


thelizman wrote
What part of "the filament can NO LONGER HANDLE THE CURRENT PASSING
THROUGH IT" escaped your comprehension, smacktard?


Tha Ghee wrote
so in fact you just proved my point, that was the whole point of the

post,
to show that you were incorrect and I wasn't. do you hate that I keep
showing you up in your only place of refuge?



  #75   Report Post  
Daniel Snooks
 
Posts: n/a
Default Capacitor, how to find out what size?


Tha Ghee wrote
what batt. can produce 6,600 watts show me some graphs, but you'll doctor
them up like you did with TN.


Even an average should be able to produce 6,600W and should be able to do it
for more the 30 seconds.

Let's look at some examples:

550CA battery 80ah rating (ah=amp hour)

@12V the above battery can produce 6,600W (12x550)
it should be able to do this for almost 9 minutes (80/550*60)
it can produce 960W continuously for an hour

I have a Motormaster Eliminator in my Sunbird

750CA, 135ah rating

@ 12V it can produce 9,000W (12x750)
it should be able to do this for about 10 minutes (135/750*60)
it can produce 1,620W continuously for an hour

I have run my stereo system off the battery for in excess of 7 hours before
(continuously). Probably drawing ~ 200W on average the entire time. Still
had enough juice left over the start the car at the end of the shift.

does my full power timeline seem correct? I made that equation up on the
fly, seems reasonable to me.

Dan Snooks




  #76   Report Post  
Daniel Snooks
 
Posts: n/a
Default Capacitor, how to find out what size?

Tha Ghee wrote
batteries don't put out power the store it, so how can they put out so
much??


You are digging a very impressive hole for yourself with these kinds of
posts. You may want to quit while you are behind.

Batteries DO "put out" (produce) power. They ALSO store it. If batteries
could not put out power, things like wris****ches, cell phones and such
wouldn't work.


  #77   Report Post  
MZ
 
Posts: n/a
Default Capacitor, how to find out what size?

You are digging a very impressive hole for yourself with these kinds of
posts. You may want to quit while you are behind.

Batteries DO "put out" (produce) power. They ALSO store it. If batteries
could not put out power, things like wris****ches, cell phones and such
wouldn't work.


Daniel, you may as well give up. Ghee and I (and Les) had a discussion
about whether or not batteries are storage devices or voltage sources, and
after being presented with all kinds of evidence that they were in fact
voltage sources (hell, they're the prototypical voltage source!), he still
maintained that they are not. You're fighting a losing battle.


  #78   Report Post  
Daniel Snooks
 
Posts: n/a
Default Capacitor, how to find out what size?

MZ wrote
Daniel, you may as well give up. Ghee and I (and Les) had a discussion
about whether or not batteries are storage devices or voltage sources, and
after being presented with all kinds of evidence that they were in fact
voltage sources (hell, they're the prototypical voltage source!), he still
maintained that they are not. You're fighting a losing battle.


Hey Mark ... still fighting the good fight I see :-)

never ceases to amaze, but if everyone agreed life would be pretty boring
I still enjoy seeing some of these guys antagonize the regulars, keeps you
all on your toes ...


  #79   Report Post  
Tha Ghee
 
Posts: n/a
Default Capacitor, how to find out what size?

"Daniel Snooks" wrote in message
. ..
Tha Ghee wrote
batteries don't put out power the store it, so how can they put out so
much??


You are digging a very impressive hole for yourself with these kinds of
posts. You may want to quit while you are behind.

Batteries DO "put out" (produce) power. They ALSO store it. If batteries
could not put out power, things like wris****ches, cell phones and such
wouldn't work.

no they store power, they don't make their own power. if a battery isn't
charged it won't do anything but take up space.

they only develop power once they're charged.

I'm not digging any hole and I'm never behind.


  #80   Report Post  
Tha Ghee
 
Posts: n/a
Default Capacitor, how to find out what size?

"Daniel Snooks" wrote in message
. ..
Notice that in the first response here, Tha Ghee asserts that most things
break when you turn them OFF. I hope he meant to say ON, or none of it

makes
any sense whatsoever.
More importantly, in the final response by Tha Ghee, he states that the
whole point of the post was to show that thelizard was incorrect. Um, he
never showed that. On a side note ... what does a lightbulb filament have

to
do with the price of escargot in Spain? IF I read this thread correctly,

the
discussion is (once again) what to do about capacitors. Are they useful?

if
so in what application, if not ... why not?

Don't think that I feel thelizard needs a hand, just putting in my $0.02

Dan Snooks

no I said "ON" just goggle it you'll see. yes I did but I can see that your
reading comprehension is low so I'll let you slide. what the hell are you
saying, this bulb post is from a previous post. if you don't know what has
been said don't say anything.

if you want to put your hand on theliz by all means go head, I think you're
one the few humans that will do it for free.


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