I bought a 1.5 F Xpress capacitor for $50 to help stabilize my car's
electrical system when I have my loud music and inverter running. I
hooked it up exactly as the book said, using the 1000 ohm resistor
between the positive terminal of the cap and the positive battery wire,
with the ground connected to the negative terminal of the cap. The
voltage before the resistor is my car's battery voltage, about 13
volts. And the voltage accross the capacitor went somewhat quickly up
to about 4 volts, then seemed to completely stop charging at about 5
volts. So I got ****ed, drove all the way back to Fry's, and traded it
for another of the exact same cap. I hooked that up the same way
again, and it is pretty much doing the same thing. I don't know if
that brand is just crap or if I'm missing something here. I did the
calculation online and a 1.5 farad cap with a 1kohm resistor at 12
volts should take about 2 hours to fully charge, although it has been
more than 2 hours and i'm still stuck at 5 volts. Someone please help
me out.

In .com, on 05/20/06

at 08:46 PM, said:

I bought a 1.5 F Xpress capacitor for $50 to help stabilize my car's
electrical system when I have my loud music and inverter running. I
hooked it up exactly as the book said, using the 1000 ohm resistor
between the positive terminal of the cap and the positive battery
wire, with the ground connected to the negative terminal of the cap.
The voltage before the resistor is my car's battery voltage, about 13
volts. And the voltage accross the capacitor went somewhat quickly up
to about 4 volts, then seemed to completely stop charging at about 5
volts. So I got ****ed, drove all the way back to Fry's, and traded
it for another of the exact same cap. I hooked that up the same way
again, and it is pretty much doing the same thing. I don't know if
that brand is just crap or if I'm missing something here. I did the
calculation online and a 1.5 farad cap with a 1kohm resistor at 12
volts should take about 2 hours to fully charge, although it has been
more than 2 hours and i'm still stuck at 5 volts. Someone please help
me out.

Read the directions some more. Leaving that 1000 Ohm resistor in place
is like using a rope to pull a trailer into place, then forgetting to
tell you to connect the trailer hitch. If you succeed in charging the
capacitor, the stereo will operate briefly, then you'll have to turn it
off and charge the capacitor again.

If your stereo or any lamps or microprocessors are running, the 1000
Ohm resistor will prevent the capacitor from ever charging. Part of the
instructions should be to disconnect all of the equipment until the
capacitor charges.

It is possible that the capacitor is old and leaking enough that it
will not charge through a 1000 Ohm resistor. The leakage may improve
over time.

Read the directions again and see if they don't tell you to remove the
1000 Ohm resistor and replace it with a direct connection -- after the
capacitor charges. The goal of that 1000 Ohm resistor is to prevent the
uncharged capacitor from appearing as a short circuit at the instant it
is connected.

I'll leave as an exercise for the student to contemplate what happens
if the battery ever looses its charge, the capacitor discharges, then
the battery is replaced.

-----------------------------------------------------------
spam:
wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13 (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------

wrote in message
oups.com...
I bought a 1.5 F Xpress capacitor for $50 to help stabilize my car's
electrical system when I have my loud music and inverter running. I
hooked it up exactly as the book said, using the 1000 ohm resistor
between the positive terminal of the cap and the positive battery wire,
with the ground connected to the negative terminal of the cap. The
voltage before the resistor is my car's battery voltage, about 13
volts. And the voltage accross the capacitor went somewhat quickly up
to about 4 volts, then seemed to completely stop charging at about 5
volts.

what are you using to measure voltage with? do you know what a voltage
divider is?


So I got ****ed, drove all the way back to Fry's, and traded it
for another of the exact same cap. I hooked that up the same way
again, and it is pretty much doing the same thing. I don't know if
that brand is just crap or if I'm missing something here. I did the
calculation online and a 1.5 farad cap with a 1kohm resistor at 12
volts should take about 2 hours to fully charge, although it has been
more than 2 hours and i'm still stuck at 5 volts. Someone please help
me out.


what good is a "stiffening" capacitor with a 1k resistor in series?

some kind of buzz filter?

"TimPerry" wrote in message
...

wrote in message
oups.com...
I bought a 1.5 F Xpress capacitor for $50 to help stabilize my car's
electrical system when I have my loud music and inverter running. I
hooked it up exactly as the book said, using the 1000 ohm resistor
between the positive terminal of the cap and the positive battery wire,
with the ground connected to the negative terminal of the cap. The
voltage before the resistor is my car's battery voltage, about 13
volts. And the voltage accross the capacitor went somewhat quickly up
to about 4 volts, then seemed to completely stop charging at about 5
volts.

what are you using to measure voltage with? do you know what a voltage
divider is?


So I got ****ed, drove all the way back to Fry's, and traded it
for another of the exact same cap. I hooked that up the same way
again, and it is pretty much doing the same thing. I don't know if
that brand is just crap or if I'm missing something here. I did the
calculation online and a 1.5 farad cap with a 1kohm resistor at 12
volts should take about 2 hours to fully charge, although it has been
more than 2 hours and i'm still stuck at 5 volts. Someone please help
me out.


what good is a "stiffening" capacitor with a 1k resistor in series?

some kind of buzz filter?

That kind of energy storage could be dangerous, and probably marginally
useful at best. I wonder how many melted wiring harnesses, blown fuses,
shorted alternator rectifiers, etc., these things cause.

Thanks for your input. Also do you know what Built-In Telay means?

Barry Mann wrote:
In .com, on 05/20/06

at 08:46 PM, said:

I bought a 1.5 F Xpress capacitor for $50 to help stabilize my car's
electrical system when I have my loud music and inverter running. I
hooked it up exactly as the book said, using the 1000 ohm resistor
between the positive terminal of the cap and the positive battery
wire, with the ground connected to the negative terminal of the cap.
The voltage before the resistor is my car's battery voltage, about 13
volts. And the voltage accross the capacitor went somewhat quickly up
to about 4 volts, then seemed to completely stop charging at about 5
volts. So I got ****ed, drove all the way back to Fry's, and traded
it for another of the exact same cap. I hooked that up the same way
again, and it is pretty much doing the same thing. I don't know if
that brand is just crap or if I'm missing something here. I did the
calculation online and a 1.5 farad cap with a 1kohm resistor at 12
volts should take about 2 hours to fully charge, although it has been
more than 2 hours and i'm still stuck at 5 volts. Someone please help
me out.

Read the directions some more. Leaving that 1000 Ohm resistor in place
is like using a rope to pull a trailer into place, then forgetting to
tell you to connect the trailer hitch. If you succeed in charging the
capacitor, the stereo will operate briefly, then you'll have to turn it
off and charge the capacitor again.

If your stereo or any lamps or microprocessors are running, the 1000
Ohm resistor will prevent the capacitor from ever charging. Part of the
instructions should be to disconnect all of the equipment until the
capacitor charges.

It is possible that the capacitor is old and leaking enough that it
will not charge through a 1000 Ohm resistor. The leakage may improve
over time.

Read the directions again and see if they don't tell you to remove the
1000 Ohm resistor and replace it with a direct connection -- after the
capacitor charges. The goal of that 1000 Ohm resistor is to prevent the
uncharged capacitor from appearing as a short circuit at the instant it
is connected.

I'll leave as an exercise for the student to contemplate what happens
if the battery ever looses its charge, the capacitor discharges, then
the battery is replaced.

-----------------------------------------------------------
spam:
wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13 (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------

In .com, on 05/20/06

at 11:04 PM, said:


Thanks for your input. Also do you know what Built-In Telay means?

No.

Could this be a misprint and they are trying to say "Relay" or "Delay"?

By the way, if you should succeed in charging this thing, be careful
not to short circuit it. A capacitor this large will make a mess out of
a screwdriver if you slip and touch both terminals.

Either the directions are incorrect or you are misreading them.

-----------------------------------------------------------
spam:
wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13 (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------

"Karl Uppiano" wrote in message
news:tgTbg.1645$oA6.1263@trnddc06...

"TimPerry" wrote in message
...

wrote in message
oups.com...
I bought a 1.5 F Xpress capacitor for $50 to help stabilize my car's
electrical system when I have my loud music and inverter running. I
hooked it up exactly as the book said, using the 1000 ohm resistor
between the positive terminal of the cap and the positive battery wire,
with the ground connected to the negative terminal of the cap. The
voltage before the resistor is my car's battery voltage, about 13
volts. And the voltage accross the capacitor went somewhat quickly up
to about 4 volts, then seemed to completely stop charging at about 5
volts.

what are you using to measure voltage with? do you know what a voltage
divider is?


So I got ****ed, drove all the way back to Fry's, and traded it
for another of the exact same cap. I hooked that up the same way
again, and it is pretty much doing the same thing. I don't know if
that brand is just crap or if I'm missing something here. I did the
calculation online and a 1.5 farad cap with a 1kohm resistor at 12
volts should take about 2 hours to fully charge, although it has been
more than 2 hours and i'm still stuck at 5 volts. Someone please help
me out.


what good is a "stiffening" capacitor with a 1k resistor in series?

some kind of buzz filter?

That kind of energy storage could be dangerous, and probably marginally
useful at best. I wonder how many melted wiring harnesses, blown fuses,
shorted alternator rectifiers, etc., these things cause.


these things are "de regular" in high power car audio. i think you charge
them up with the resister to avoid huge inrush current and the assisiated
spark. then they are premanantly attached to +12 without the resistor.

the idea is to smooth out the voltage drop accoss the DC wire to the battery
when a high energy pulse such as a bass beat demands a huge amount of
current.

You take the resistor away once the cap is charged.
Didn't instructions come with it? Here's some:
http://www.caraudiohelp.com/car_audi...stallation.htm

TimPerry wrote:

these things are "de regular" in high power car audio.

French "de rigeur" meaning "strictly required". As other people have
commented there are safety considerations that need to be done.

In this context it seems prudent to suggest that intallation should be
done by a proficient installer instead of by a person with an incomplete
understanding of car and car stereo electrics.

See also: alt.support.tinnitus ....


Kind regards

Peter Larsen

--
*******************************************
* My site is at: http://www.muyiovatki.dk *
*******************************************

wrote:

I bought a 1.5 F Xpress capacitor for $50 to help stabilize my car's
electrical system when I have my loud music and inverter running. I
hooked it up exactly as the book said, using the 1000 ohm resistor
between the positive terminal of the cap and the positive battery wire,
with the ground connected to the negative terminal of the cap. The
voltage before the resistor is my car's battery voltage, about 13
volts. And the voltage accross the capacitor went somewhat quickly up
to about 4 volts, then seemed to completely stop charging at about 5
volts. So I got ****ed, drove all the way back to Fry's, and traded it
for another of the exact same cap. I hooked that up the same way
again, and it is pretty much doing the same thing. I don't know if
that brand is just crap or if I'm missing something here. I did the
calculation online and a 1.5 farad cap with a 1kohm resistor at 12
volts should take about 2 hours to fully charge, although it has been
more than 2 hours and i'm still stuck at 5 volts. Someone please help
me out.

Most likely explanation is that the negative end of the cap is not
connected to ground. Are you sure you are correctly grounded? What are
you using for the ground connection?

"Peter Larsen" wrote in message
...
TimPerry wrote:

these things are "de regular" in high power car audio.

French "de rigeur" meaning "strictly required". As other people have
commented there are safety considerations that need to be done.

In this context it seems prudent to suggest that intallation should be
done by a proficient installer instead of by a person with an incomplete
understanding of car and car stereo electrics.

See also: alt.support.tinnitus ....


Kind regards

Peter Larsen

parden my french please

i ment "commonly seen"

i have had a giant electrolytic explode with spectacular results. my
recomendation is don't put it in at all.

"TimPerry" wrote in message
...

"Karl Uppiano" wrote in message
news:tgTbg.1645$oA6.1263@trnddc06...

"TimPerry" wrote in message
...

wrote in message
oups.com...
I bought a 1.5 F Xpress capacitor for $50 to help stabilize my car's
electrical system when I have my loud music and inverter running. I
hooked it up exactly as the book said, using the 1000 ohm resistor
between the positive terminal of the cap and the positive battery
wire,
with the ground connected to the negative terminal of the cap. The
voltage before the resistor is my car's battery voltage, about 13
volts. And the voltage accross the capacitor went somewhat quickly up
to about 4 volts, then seemed to completely stop charging at about 5
volts.

what are you using to measure voltage with? do you know what a voltage
divider is?


So I got ****ed, drove all the way back to Fry's, and traded it
for another of the exact same cap. I hooked that up the same way
again, and it is pretty much doing the same thing. I don't know if
that brand is just crap or if I'm missing something here. I did the
calculation online and a 1.5 farad cap with a 1kohm resistor at 12
volts should take about 2 hours to fully charge, although it has been
more than 2 hours and i'm still stuck at 5 volts. Someone please help
me out.


what good is a "stiffening" capacitor with a 1k resistor in series?

some kind of buzz filter?

That kind of energy storage could be dangerous, and probably marginally
useful at best. I wonder how many melted wiring harnesses, blown fuses,
shorted alternator rectifiers, etc., these things cause.


these things are "de regular" in high power car audio. i think you charge
them up with the resister to avoid huge inrush current and the assisiated
spark. then they are premanantly attached to +12 without the resistor.

Right. But what happens when someone simply disconnects the battery cables
for some reason, and the thing discharges? The huge inrush will occur unless
big warnings are plastered everywhere. The inrush could blow fuses and melt
down wiring harnesses.

the idea is to smooth out the voltage drop accoss the DC wire to the
battery
when a high energy pulse such as a bass beat demands a huge amount of
current.

I understand the theory, I just question the solution. Why not just run
heavier cables between the battery and the load?

Right. But what happens when someone simply disconnects the battery cables
for some reason, and the thing discharges? The huge inrush will occur
unless
big warnings are plastered everywhere. The inrush could blow fuses and
melt
down wiring harnesses.


typically these are used with awg 8, 6, 4 , or larger cable.


the idea is to smooth out the voltage drop accoss the DC wire to the
battery
when a high energy pulse such as a bass beat demands a huge amount of
current.

I understand the theory, I just question the solution. Why not just run
heavier cables between the battery and the load?


the ridiculous amount of peak current demanded by the ridiculous amplifier.
at 100 amps .1 ohms of resistance would be a 10 volt drop.

say you run both plus and minus to the battery for a total of 30 feet using
8 AWG copper. if the resistance is .64 ohms per 1000 ft and peak current is
100 (just to pick a round number) voltage drop on the wire is going to be
something like 1.92 volts.
the internal resistance of the battery and whether or not the alternator is
running will also determine the voltage at the load.

"TimPerry" wrote in message
news

Right. But what happens when someone simply disconnects the battery
cables
for some reason, and the thing discharges? The huge inrush will occur
unless
big warnings are plastered everywhere. The inrush could blow fuses and
melt
down wiring harnesses.


typically these are used with awg 8, 6, 4 , or larger cable.


the idea is to smooth out the voltage drop accoss the DC wire to the
battery
when a high energy pulse such as a bass beat demands a huge amount of
current.

I understand the theory, I just question the solution. Why not just run
heavier cables between the battery and the load?


the ridiculous amount of peak current demanded by the ridiculous
amplifier.
at 100 amps .1 ohms of resistance would be a 10 volt drop.

So it's not the cap that's ridiculous; it's the entire thing.

say you run both plus and minus to the battery for a total of 30 feet
using
8 AWG copper. if the resistance is .64 ohms per 1000 ft and peak current
is
100 (just to pick a round number) voltage drop on the wire is going to be
something like 1.92 volts.
the internal resistance of the battery and whether or not the alternator
is
running will also determine the voltage at the load.

Then I guess the thing to do would be to put a regulated inverter right next
to the batter/alternator and run the amplifiers at 120 volts or so.

"Karl Uppiano" wrote in message
news:bA3cg.2904$oA6.1302@trnddc06...

"TimPerry" wrote in message
news

Right. But what happens when someone simply disconnects the battery
cables
for some reason, and the thing discharges? The huge inrush will occur
unless
big warnings are plastered everywhere. The inrush could blow fuses and
melt
down wiring harnesses.


typically these are used with awg 8, 6, 4 , or larger cable.


the idea is to smooth out the voltage drop accoss the DC wire to the
battery
when a high energy pulse such as a bass beat demands a huge amount of
current.

I understand the theory, I just question the solution. Why not just run
heavier cables between the battery and the load?


the ridiculous amount of peak current demanded by the ridiculous
amplifier.
at 100 amps .1 ohms of resistance would be a 10 volt drop.

So it's not the cap that's ridiculous; it's the entire thing.

specifically the concept of creating a continuous load on the charging
system that is near maximum or exceeds the maximum amount of current it is
rated for.




say you run both plus and minus to the battery for a total of 30 feet
using
8 AWG copper. if the resistance is .64 ohms per 1000 ft and peak current
is
100 (just to pick a round number) voltage drop on the wire is going to
be
something like 1.92 volts.
the internal resistance of the battery and whether or not the alternator
is
running will also determine the voltage at the load.

Then I guess the thing to do would be to put a regulated inverter right
next
to the batter/alternator and run the amplifiers at 120 volts or so.


this is kind of what i do, sometimes, for live events at locations where
there is no power.
2 deep cycle batteries in parallel loaded by a 1200W /2400W peak inverter.

typically i get a couple hours use with the engine off.

in the past i rigged a system using 4 golf cart batteries in series parallel
and a DBI (dual battery isolator) for use with a "live" truck. the problem
here is that the drive time following each event was insufficient to
recharge the depleted batterys. they required a couple days of recharging
which the people who were operating the thing refused to do.

some of the trucks an vans that kind of fall under my area of responsibility
have car audio power amps installed. they are cabled to PA speakers. the
operators have been known to deplete the battery in 30 min. or so while
lining up for a parade.

the (only) advantage (IMO) in this type of system is you don't have the
noise of a generator and you don't have to breath gasoline fumes as you
drive to an from an event.
the advantage, from the operators point of view is it's real easy: you don't
have to unwind an extension cord and plug into an outlet. OMG you have to
wind it up at the end of a show. how awful.dripping sarcasm

Karl Uppiano wrote:
"TimPerry" wrote in message
...
"Karl Uppiano" wrote in message
news:tgTbg.1645$oA6.1263@trnddc06...
"TimPerry" wrote in message
...
wrote in message
oups.com...
I bought a 1.5 F Xpress capacitor for $50 to help stabilize my car's
electrical system when I have my loud music and inverter running. I
hooked it up exactly as the book said, using the 1000 ohm resistor
between the positive terminal of the cap and the positive battery
wire,
with the ground connected to the negative terminal of the cap. The
voltage before the resistor is my car's battery voltage, about 13
volts. And the voltage accross the capacitor went somewhat quickly up
to about 4 volts, then seemed to completely stop charging at about 5
volts.
what are you using to measure voltage with? do you know what a voltage
divider is?


So I got ****ed, drove all the way back to Fry's, and traded it
for another of the exact same cap. I hooked that up the same way
again, and it is pretty much doing the same thing. I don't know if
that brand is just crap or if I'm missing something here. I did the
calculation online and a 1.5 farad cap with a 1kohm resistor at 12
volts should take about 2 hours to fully charge, although it has been
more than 2 hours and i'm still stuck at 5 volts. Someone please help
me out.

what good is a "stiffening" capacitor with a 1k resistor in series?

some kind of buzz filter?
That kind of energy storage could be dangerous, and probably marginally
useful at best. I wonder how many melted wiring harnesses, blown fuses,
shorted alternator rectifiers, etc., these things cause.

They shouldn't cause any of the above, if properly implemented. IMO,
there should be a relay to safely charge the unit initially, and to
disconnect if from the system when the ignition is switched off, with a
bleed resistor to take the charge off it.

these things are "de regular" in high power car audio. i think you charge
them up with the resister to avoid huge inrush current and the assisiated
spark. then they are premanantly attached to +12 without the resistor.

Right. But what happens when someone simply disconnects the battery cables
for some reason, and the thing discharges? The huge inrush will occur unless
big warnings are plastered everywhere. The inrush could blow fuses and melt
down wiring harnesses.

I'm trying to figure out how that could happen, even without the safety
measures I mentioned above. Why would there be a 'massive inrush' when
the battery was disco'd? There's only 12 volts (nominal) on this thing.
Sure, it can supply a lot of current in a hurry (it's intended
application in this case) but unless something is *drawing* massive
current...and what would that be?

If the system is installed correctly, there is a fairly hefty fused lead
from the battery to the cap, probably enough to supply normal load for
the vehicle, except for the starter. In the scenario you
describe--assuming someone would disconnect the battery with the engine
running (and why would they?)--the cap simply would backfeed powering
the electrical system until it was discharged...nothing massive.

If someone disconnected the battery, then dropped the positive lead to
ground, there might be a problem; but I'm assuming anyone doing such an
installation correctly would have fused the feed to the cap. I've seen
huge fuse blocks for this purpose in the sound departments at auto parts
stores.

the idea is to smooth out the voltage drop accoss the DC wire to the
battery
when a high energy pulse such as a bass beat demands a huge amount of
current.

I understand the theory, I just question the solution. Why not just run
heavier cables between the battery and the load?

This is answered later in this thread. Sure, there's a bit of
'phoolery' in the implementation; but the theory is fairly sound. It's
not intended to supply current all of the time, only on peaks...the same
reason there are big filter caps in good audio amps.

OTOH, I'm sure that people overuse--and misuse--them....

jak

"jakdedert" wrote in message
. ..
Karl Uppiano wrote:
"TimPerry" wrote in message
...
"Karl Uppiano" wrote in message
news:tgTbg.1645$oA6.1263@trnddc06...
"TimPerry" wrote in message
...
wrote in message
oups.com...
I bought a 1.5 F Xpress capacitor for $50 to help stabilize my car's
electrical system when I have my loud music and inverter running. I
hooked it up exactly as the book said, using the 1000 ohm resistor
between the positive terminal of the cap and the positive battery
wire,
with the ground connected to the negative terminal of the cap. The
voltage before the resistor is my car's battery voltage, about 13
volts. And the voltage accross the capacitor went somewhat quickly
up
to about 4 volts, then seemed to completely stop charging at about 5
volts.
what are you using to measure voltage with? do you know what a voltage
divider is?


So I got ****ed, drove all the way back to Fry's, and traded it
for another of the exact same cap. I hooked that up the same way
again, and it is pretty much doing the same thing. I don't know if
that brand is just crap or if I'm missing something here. I did the
calculation online and a 1.5 farad cap with a 1kohm resistor at 12
volts should take about 2 hours to fully charge, although it has been
more than 2 hours and i'm still stuck at 5 volts. Someone please
help
me out.

what good is a "stiffening" capacitor with a 1k resistor in series?

some kind of buzz filter?
That kind of energy storage could be dangerous, and probably marginally
useful at best. I wonder how many melted wiring harnesses, blown fuses,
shorted alternator rectifiers, etc., these things cause.

They shouldn't cause any of the above, if properly implemented. IMO,
there should be a relay to safely charge the unit initially, and to
disconnect if from the system when the ignition is switched off, with a
bleed resistor to take the charge off it.

these things are "de regular" in high power car audio. i think you
charge
them up with the resister to avoid huge inrush current and the
assisiated
spark. then they are premanantly attached to +12 without the resistor.

Right. But what happens when someone simply disconnects the battery
cables for some reason, and the thing discharges? The huge inrush will
occur unless big warnings are plastered everywhere. The inrush could blow
fuses and melt down wiring harnesses.

I'm trying to figure out how that could happen, even without the safety
measures I mentioned above. Why would there be a 'massive inrush' when
the battery was disco'd? There's only 12 volts (nominal) on this thing.
Sure, it can supply a lot of current in a hurry (it's intended application
in this case) but unless something is *drawing* massive current...and what
would that be?

If the system is installed correctly, there is a fairly hefty fused lead
from the battery to the cap, probably enough to supply normal load for the
vehicle, except for the starter. In the scenario you describe--assuming
someone would disconnect the battery with the engine running (and why
would they?)--the cap simply would backfeed powering the electrical system
until it was discharged...nothing massive.

Yes, but when they reconnect the battery, look out. That's what I really
meant.

If someone disconnected the battery, then dropped the positive lead to
ground, there might be a problem; but I'm assuming anyone doing such an
installation correctly would have fused the feed to the cap. I've seen
huge fuse blocks for this purpose in the sound departments at auto parts
stores.

the idea is to smooth out the voltage drop accoss the DC wire to the
battery
when a high energy pulse such as a bass beat demands a huge amount of
current.

I understand the theory, I just question the solution. Why not just run
heavier cables between the battery and the load?

This is answered later in this thread. Sure, there's a bit of 'phoolery'
in the implementation; but the theory is fairly sound. It's not intended
to supply current all of the time, only on peaks...the same reason there
are big filter caps in good audio amps.

Well designed amps have right-sized, not oversized filter caps. Oh well...

OTOH, I'm sure that people overuse--and misuse--them....

jak

Karl Uppiano wrote:
"jakdedert" wrote in message
snip
Right. But what happens when someone simply disconnects the battery
cables for some reason, and the thing discharges? The huge inrush will
occur unless big warnings are plastered everywhere. The inrush could blow
fuses and melt down wiring harnesses.

I'm trying to figure out how that could happen, even without the safety
measures I mentioned above. Why would there be a 'massive inrush' when
the battery was disco'd? There's only 12 volts (nominal) on this thing.
Sure, it can supply a lot of current in a hurry (it's intended application
in this case) but unless something is *drawing* massive current...and what
would that be?

If the system is installed correctly, there is a fairly hefty fused lead
from the battery to the cap, probably enough to supply normal load for the
vehicle, except for the starter. In the scenario you describe--assuming
someone would disconnect the battery with the engine running (and why
would they?)--the cap simply would backfeed powering the electrical system
until it was discharged...nothing massive.

Yes, but when they reconnect the battery, look out. That's what I really
meant.

Okay, I can see that. Hopefully the line is fused. If the thing was
installed as I recommended, that would not be a problem, but I doubt
that's the case.

snip
Well designed amps have right-sized, not oversized filter caps. Oh well...

Your word, oversized, implies bad design. Right-sized, in the case of
professional amps, is usually pretty big....

jak

Peter Larsen wrote:
TimPerry wrote:


these things are "de regular" in high power car audio.


French "de rigeur" meaning "strictly required". As other people have
commented there are safety considerations that need to be done.

In this context it seems prudent to suggest that intallation should be
done by a proficient installer instead of by a person with an incomplete
understanding of car and car stereo electrics.

For that matter, 99% chance it's not needed in the first place. Very
few systems REALLY need them, and they're more often than not used to
compensate for an underpowered charging system. In reality, a cap
should be the LAST thing used to solidify a system, AFTER the alternator
and battery have been beefed up.


See also: alt.support.tinnitus ....

Heheheh.


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Karl Uppiano wrote:

these things are "de regular" in high power car audio. i think you charge
them up with the resister to avoid huge inrush current and the assisiated
spark. then they are premanantly attached to +12 without the resistor.


Right. But what happens when someone simply disconnects the battery cables
for some reason, and the thing discharges?

No, because it has nowhere to discharge to. If the system is still
running when the battery is disconnected, it may keep the amp running a
couple seconds longer, and drain out through there, but only until the
turn-on lead shuts down anyway.

The huge inrush will occur unless
big warnings are plastered everywhere. The inrush could blow fuses and melt
down wiring harnesses.

Uh, no... the only wires that have to carry that current are the leads
connected directly to the cap, and if you're drawing enough current to
even need a cap, those should be pretty hefty cables to begin with.

I understand the theory, I just question the solution. Why not just run
heavier cables between the battery and the load?

This is the thing: a cap is the LAST thing you should add to a system.
If your amps are drawing so much current that your lights are dimming,
then you're not PRODUCING enough current to begin with. A cap won't fix
that problem, a deep-cycle battery won't fix that problem; the only
thing that will help that is to PRODUCE more power, and that requires a
higher-capacity alternator.


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Robert Gault wrote:
wrote:

I bought a 1.5 F Xpress capacitor for $50 to help stabilize my car's
electrical system when I have my loud music and inverter running. I
hooked it up exactly as the book said, using the 1000 ohm resistor
between the positive terminal of the cap and the positive battery wire,
with the ground connected to the negative terminal of the cap. The
voltage before the resistor is my car's battery voltage, about 13
volts. And the voltage accross the capacitor went somewhat quickly up
to about 4 volts, then seemed to completely stop charging at about 5
volts. So I got ****ed, drove all the way back to Fry's, and traded it
for another of the exact same cap. I hooked that up the same way
again, and it is pretty much doing the same thing. I don't know if
that brand is just crap or if I'm missing something here. I did the
calculation online and a 1.5 farad cap with a 1kohm resistor at 12
volts should take about 2 hours to fully charge, although it has been
more than 2 hours and i'm still stuck at 5 volts. Someone please help
me out.

Most likely explanation is that the negative end of the cap is not
connected to ground. Are you sure you are correctly grounded? What are
you using for the ground connection?

If the negative side of the cap wasn't grounded, the cap wouldn't charge
AT ALL.


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TimPerry wrote:
"Peter Larsen" wrote in message
...

TimPerry wrote:


these things are "de regular" in high power car audio.

French "de rigeur" meaning "strictly required". As other people have
commented there are safety considerations that need to be done.

In this context it seems prudent to suggest that intallation should be
done by a proficient installer instead of by a person with an incomplete
understanding of car and car stereo electrics.

See also: alt.support.tinnitus ....


Kind regards

Peter Larsen


parden my french please

i ment "commonly seen"

i have had a giant electrolytic explode with spectacular results. my
recomendation is don't put it in at all.

A friend of mine took an EE course in college once years ago, with an
instructor who liked to demonstrate quite vividly for each new class,
what happens when a big electrolytic is hooked up wrong... but taking a
470,000uF cap and hooking it up to a line cord... then getting everyone
to the other side of the room and plugging the cord into the wall.

"Spectacular" would be a good word to describe the results.

We used to have a fun little trick when I was working in a larger
car-audio install shop... when a guy is putting in an alarm, sneak in
under the hood while he's working inside the car or gone out for a
smoke, and connect a small-ish (maybe 4700uF), low-voltage (6VDC)
electrolytic reverse-polatiry across his siren or light-flash leads
*UNDER THE HOOD* (NOT inside the car). First time he tests it...
*chirp-chirp* BANG! and a little puff of nasty-smelling black smoke from
under the hood. Great fun!


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Matt Ion wrote:

Robert Gault wrote:

wrote:

I bought a 1.5 F Xpress capacitor for $50 to help stabilize my car's
electrical system when I have my loud music and inverter running. I
hooked it up exactly as the book said, using the 1000 ohm resistor
between the positive terminal of the cap and the positive battery wire,
with the ground connected to the negative terminal of the cap. The
voltage before the resistor is my car's battery voltage, about 13
volts. And the voltage accross the capacitor went somewhat quickly up
to about 4 volts, then seemed to completely stop charging at about 5
volts. So I got ****ed, drove all the way back to Fry's, and traded it
for another of the exact same cap. I hooked that up the same way
again, and it is pretty much doing the same thing. I don't know if
that brand is just crap or if I'm missing something here. I did the
calculation online and a 1.5 farad cap with a 1kohm resistor at 12
volts should take about 2 hours to fully charge, although it has been
more than 2 hours and i'm still stuck at 5 volts. Someone please help
me out.

Most likely explanation is that the negative end of the cap is not
connected to ground. Are you sure you are correctly grounded? What are
you using for the ground connection?


If the negative side of the cap wasn't grounded, the cap wouldn't charge
AT ALL.


But if it is connected not to ground but through resistance, then the
cap would not fully charge.

Robert Gault wrote:
Matt Ion wrote:

Robert Gault wrote:

wrote:

I bought a 1.5 F Xpress capacitor for $50 to help stabilize my car's
electrical system when I have my loud music and inverter running. I
hooked it up exactly as the book said, using the 1000 ohm resistor
between the positive terminal of the cap and the positive battery wire,
with the ground connected to the negative terminal of the cap. The
voltage before the resistor is my car's battery voltage, about 13
volts. And the voltage accross the capacitor went somewhat quickly up
to about 4 volts, then seemed to completely stop charging at about 5
volts. So I got ****ed, drove all the way back to Fry's, and traded it
for another of the exact same cap. I hooked that up the same way
again, and it is pretty much doing the same thing. I don't know if
that brand is just crap or if I'm missing something here. I did the
calculation online and a 1.5 farad cap with a 1kohm resistor at 12
volts should take about 2 hours to fully charge, although it has been
more than 2 hours and i'm still stuck at 5 volts. Someone please help
me out.

Most likely explanation is that the negative end of the cap is not
connected to ground. Are you sure you are correctly grounded? What
are you using for the ground connection?



If the negative side of the cap wasn't grounded, the cap wouldn't
charge AT ALL.


But if it is connected not to ground but through resistance, then the
cap would not fully charge.

Yes it would. It would just take longer to do so. 5RC.


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Connecting 1.5F (or any other cap) into a battery power circuit via a
1k resistor won't do anything. You need VERY low impedance connections
from the cap to the power amp (or whatever) to have it work.

Some supercaps have built-in LEDs, discharge resistors, etc that would
prevent a full charge when fed via a resistor (just as you
experienced). If your 1k resistor drops 7V when feeding the supercap,
that's 7mA, and if you eliminate the resistor, whatever's in the
supercap may draw 20mA or more at 12V, so make sure the circuit is
switched so it doesn't flatten your battery if you leave it unattended
for a month or more.

Does the book mention why they suggest the 1k resistor?

Tony

wrote:

I bought a 1.5 F Xpress capacitor for $50 to help stabilize my car's
electrical system when I have my loud music and inverter running. I
hooked it up exactly as the book said, using the 1000 ohm resistor
between the positive terminal of the cap and the positive battery wire,
with the ground connected to the negative terminal of the cap. The
voltage before the resistor is my car's battery voltage, about 13
volts. And the voltage accross the capacitor went somewhat quickly up
to about 4 volts, then seemed to completely stop charging at about 5
volts. So I got ****ed, drove all the way back to Fry's, and traded it
for another of the exact same cap. I hooked that up the same way
again, and it is pretty much doing the same thing. I don't know if
that brand is just crap or if I'm missing something here. I did the
calculation online and a 1.5 farad cap with a 1kohm resistor at 12
volts should take about 2 hours to fully charge, although it has been
more than 2 hours and i'm still stuck at 5 volts. Someone please help
me out.

Tony (remove the "_" to reply by email)

Tony wrote:

Connecting 1.5F (or any other cap) into a battery power circuit via a
1k resistor won't do anything. You need VERY low impedance connections
from the cap to the power amp (or whatever) to have it work.

Some supercaps have built-in LEDs, discharge resistors, etc that would
prevent a full charge when fed via a resistor (just as you
experienced). If your 1k resistor drops 7V when feeding the supercap,
that's 7mA, and if you eliminate the resistor, whatever's in the
supercap may draw 20mA or more at 12V, so make sure the circuit is
switched so it doesn't flatten your battery if you leave it unattended
for a month or more.

100 ohms ( use a ~ 3 watt type ) would make more sense. It'll still take several
minutes to charge.

Graham

Pooh Bear wrote:
Tony wrote:

Connecting 1.5F (or any other cap) into a battery power circuit via a
1k resistor won't do anything. You need VERY low impedance
connections from the cap to the power amp (or whatever) to have it
work.

Some supercaps have built-in LEDs, discharge resistors, etc that
would prevent a full charge when fed via a resistor (just as you
experienced). If your 1k resistor drops 7V when feeding the supercap,
that's 7mA, and if you eliminate the resistor, whatever's in the
supercap may draw 20mA or more at 12V, so make sure the circuit is
switched so it doesn't flatten your battery if you leave it
unattended for a month or more.

100 ohms ( use a ~ 3 watt type ) would make more sense. It'll still
take several minutes to charge.

Graham

use a taillight bulb... when it stops glowing its done

On Fri, 26 May 2006 23:43:27 -0400, "TimPerry"
wrote:

Pooh Bear wrote:
Tony wrote:

Connecting 1.5F (or any other cap) into a battery power circuit via a
1k resistor won't do anything. You need VERY low impedance
connections from the cap to the power amp (or whatever) to have it
work.

Some supercaps have built-in LEDs, discharge resistors, etc that
would prevent a full charge when fed via a resistor (just as you
experienced). If your 1k resistor drops 7V when feeding the supercap,
that's 7mA, and if you eliminate the resistor, whatever's in the
supercap may draw 20mA or more at 12V, so make sure the circuit is
switched so it doesn't flatten your battery if you leave it
unattended for a month or more.

100 ohms ( use a ~ 3 watt type ) would make more sense. It'll still
take several minutes to charge.

Graham

use a taillight bulb... when it stops glowing its done

Supercaps certainly might prefer to be charged relatively slowly, but
even 100 ohms with 1.5F is a 150 second time constant, so needs 5
minutses or so for a reasonable charge. A taillight bulb would be much
faster, and with a little more constant current (also good). But
clearly I'm missing something here; what does any of that do to
stabilize the car's battery/amplifier system, unless the load connects
directly to the supercap (which is clearly impossible if it's fed via
such an impedance)? Are these things just for show? Is this thread
really a joke that I'm not getting?

Tony
Tony (remove the "_" to reply by email)

Tony wrote:

On Fri, 26 May 2006 23:43:27 -0400, "TimPerry"
wrote:

Pooh Bear wrote:
Tony wrote:

Connecting 1.5F (or any other cap) into a battery power circuit via a
1k resistor won't do anything. You need VERY low impedance
connections from the cap to the power amp (or whatever) to have it
work.

Some supercaps have built-in LEDs, discharge resistors, etc that
would prevent a full charge when fed via a resistor (just as you
experienced). If your 1k resistor drops 7V when feeding the supercap,
that's 7mA, and if you eliminate the resistor, whatever's in the
supercap may draw 20mA or more at 12V, so make sure the circuit is
switched so it doesn't flatten your battery if you leave it
unattended for a month or more.

100 ohms ( use a ~ 3 watt type ) would make more sense. It'll still
take several minutes to charge.

Graham

use a taillight bulb... when it stops glowing its done

Supercaps certainly might prefer to be charged relatively slowly, but
even 100 ohms with 1.5F is a 150 second time constant, so needs 5
minutses or so for a reasonable charge. A taillight bulb would be much
faster, and with a little more constant current (also good). But
clearly I'm missing something here; what does any of that do to
stabilize the car's battery/amplifier system, unless the load connects
directly to the supercap (which is clearly impossible if it's fed via
such an impedance)? Are these things just for show? Is this thread
really a joke that I'm not getting?

The 100 ohm/tail lamp whatever is just to charge the thing up safely. In use
it's removed.

Graham

The resistor or tail lamp are wired between the battery and the
capacitor. Once the capacitor is charged you should replace the
resistor or tail lamp with a fuse.

The audio system is connected to the capacitor with a fat wire.

The capacitor and fat wire can smooth over minor variations in the
car's electrical system and help the audio system out during large bass
thumps.

Note that this capacitor doesn't know or care who is asking for some
energy. If there is a minor dip in the alternator's output, the
capacitor will try to help out the headlights and car's battery too.

-----------------------------------------------------------
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wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13 (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------

Barry Mann wrote:

The resistor or tail lamp are wired between the battery and the
capacitor. Once the capacitor is charged you should replace the
resistor or tail lamp with a fuse.

The audio system is connected to the capacitor with a fat wire.

A low value resisitor might make more sense or even a schottky diode.

The capacitor and fat wire can smooth over minor variations in the
car's electrical system and help the audio system out during large bass
thumps.

Note that this capacitor doesn't know or care who is asking for some
energy. If there is a minor dip in the alternator's output, the
capacitor will try to help out the headlights and car's battery too.

Yes. which ultimately limits the sense of such a scheme. A power inveter would
be more sensible since it can raise the 12V to something more practical as well.

Graham

Tony wrote:

Supercaps certainly might prefer to be charged relatively slowly, but
even 100 ohms with 1.5F is a 150 second time constant, so needs 5
minutses or so for a reasonable charge. A taillight bulb would be much
faster, and with a little more constant current (also good).

The ONLY time you put a resistance in series with the cap is for the
initial charging, otherwise an uncharged cap initially looks like a
dead-short and the instantaneous current draw will likely blow the fuse
(that one SHOULD have AT THE BATTERY), or potentially melt the wire's
insulation, or at the very least produce a really big spark.

Once the cap is charged, the resistance is removed from the circuit.

clearly I'm missing something here; what does any of that do to
stabilize the car's battery/amplifier system, unless the load connects
directly to the supercap (which is clearly impossible if it's fed via
such an impedance)? Are these things just for show? Is this thread
really a joke that I'm not getting?

Caps CAN be useful for systems with very heavy current draw; they're
mounted near the amps with very short connections from the cap to the
amp's power input. The idea is to compensate for the resistance of a
long power feed from the battery, and for a battery's internal
resistance that can limit the speed at which it can satisfy
instantaneous high-current demands, such as you might get a very heavy
kick-drum hit, or maybe an explosion (see: 1812 Overture).

Unfortunately they've been marketed as a quick-fix for all manner of
other system deficiencies, such as an under-powered alternator, and are
typically thought of as cure-all for problems like bass hits causing
one's lights to dim.

Usually such system deficiencies are addressed in exactly the opposite
order that they should be - first a cap is added, then a heavy-duty
deep-cycle battery (again, because too many people have heard of or seen
these things in high-end systems and figure it's "required", without
actually understanding what function they perform), and finally the
alternator is upgraded. Of course, this is also usually the ascending
scale of cost - the cheapest "fix" is applied first, instead of the
proper one.


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In , on 05/29/06
at 02:45 AM, Pooh Bear
said:

A low value resisitor might make more sense or even a schottky diode.

The diode is obvious, but we know that someone will forget to pre
charge the capacitor and blow up the diode. We can't even depend on the
wiring harness internal impedance to limit the current because someone
will change that. The diode and current limit resistor would need to be
buried inside the capacitor assembly.

-----------------------------------------------------------
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wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13 (Barry Mann)
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-----------------------------------------------------------

Barry Mann wrote:

The diode and current limit resistor would need to be
buried inside the capacitor assembly.

Now that's not a bad idea.

Graham

Barry Mann wrote:
The resistor or tail lamp are wired between the battery and the
capacitor. Once the capacitor is charged you should replace the
resistor or tail lamp with a fuse.

The audio system is connected to the capacitor with a fat wire.

The capacitor and fat wire can smooth over minor variations in the
car's electrical system and help the audio system out during large bass
thumps.

Note that this capacitor doesn't know or care who is asking for some
energy. If there is a minor dip in the alternator's output, the
capacitor will try to help out the headlights and car's battery too.



Wouldn`t it be easier and cheaper to just use a second car battery? or a
larger main battery? or am I missing something here?

Ron(UK)

In , on 05/29/06
at 12:53 PM, "Ron(UK)" said:
[ ... ]
Wouldn`t it be easier and cheaper to just use a second car battery? or
a larger main battery? or am I missing something here?

There is a L-A-R-G-E population segment that is driven more by legend
and folklore than fact and engineering. Besides, if it only costs
$50-100 and "the guy" said it would make things better, why not? There
is just enough mystery associated with a capacitor (it sounds so
technical) that people believe it will perform some sort of voodoo
magic.

I don't like the idea of a second battery unless there is some sort of
charging management. If two batteries are identical, a parallel scheme
can work, but in the uncontrolled environment of a car, they won't be
identical for long.

--

In my opinion a capacitor is mostly a paste-on attempt to salvage a bad
installation. With proper charge current limiting, a diode, an RF choke
and bypass, a capacitor might improve an already competent system, but
I'd much prefer that the system components be properly designed and not
need the capacitor in the first place.

While hostile, the auto environment is well understood and one can
design equipment that will flourish -- for a price. I'm not sure how a
$200.00 (installed) system is up to that task.

-----------------------------------------------------------
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wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13 (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------

Barry Mann wrote:
In , on 05/29/06
at 12:53 PM, "Ron(UK)" said:
[ ... ]

Wouldn`t it be easier and cheaper to just use a second car battery? or
a larger main battery? or am I missing something here?


There is a L-A-R-G-E population segment that is driven more by legend
and folklore than fact and engineering. Besides, if it only costs
$50-100 and "the guy" said it would make things better, why not? There
is just enough mystery associated with a capacitor (it sounds so
technical) that people believe it will perform some sort of voodoo
magic.

Well put

I don't like the idea of a second battery unless there is some sort of
charging management. If two batteries are identical, a parallel scheme
can work, but in the uncontrolled environment of a car, they won't be
identical for long.

That's why battery isolators are used. They're a pretty straighforward
device, inexpensive and readily available from any RV-accessories
dealer. They give the added benefit of not allowing your stereo to
drain your main battery, so you never get stuck with a dead battery.

-----

What Ron is missing is the difference in functions performed by a
battery vs. a capacitor. A battery is designed to store large amounts
of energy and release it gradually. A capacitor is designed to store
smaller amounts of energy but release it very quickly.

However, neither will compensate properly for the deficiency most people
are try to cover with them: lack of sufficient current supply, which
requires a heftier alternator, period. As I've already noted in this
thread, most people tend to attack the problem by using the cheapest
patch first, when the PROPER fix is unforunately usually the most expensive.


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Pooh Bear wrote:
Barry Mann wrote:

The diode and current limit resistor would need to be
buried inside the capacitor assembly.

Now that's not a bad idea.

Graham


lets sell the idea to Behringer.... the
EuroUltraStiffeningCapProtectionSystem2006.

lets sell the idea to Behringer.... the
EuroUltraStiffeningCapProtectionSystem2006.

You don't have to SELL it to Behringer. If it's any good they'll nick
it :-)

ducks for cover

Laurence Payne wrote:

lets sell the idea to Behringer.... the
EuroUltraStiffeningCapProtectionSystem2006.

You don't have to SELL it to Behringer. If it's any good they'll nick
it :-)

So, so true.

ducks for cover

Lol !

Graham

p.s. btw I have a solution to the dissipation caused by the series diode btw. (
i.e to reduce it to nearly nil ).