Re: Car stereo capacitor not charging


"TimPerry" <timperry@xxxxxxxxxxxxxxxxxxx> wrote in message
news:FqadneXYlMMqqe3ZnZ2dnUVZ_t-dnZ2d@xxxxxxxxxxxxxxx

"Karl Uppiano" <karl.uppiano@xxxxxxxxxxx> wrote in message
news:tgTbg.1645$oA6.1263@xxxxxxxxxxx

"TimPerry" <timperry@xxxxxxxxxxxxxxxxxxx> wrote in message
news:aOednVpqJ6FVY_LZnZ2dnUVZ_uWdnZ2d@xxxxxxxxxxxxxxx

<subliznime@xxxxxxxxx> wrote in message
news:1148183175.583325.294200@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
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 pissed, 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?


.

Relevant Pages

  • Re: He who laugh last, laughs loudest, was Re: Wet your pants funny-- A.J. as an EE
    ... if you look at the LM675 spec sheet it shows 90db of power supply ... If the power supply voltage varies ... going to get 60 volts peak-to-peak out, which is about 20 volts RMS ... So this added resistor has used up all the IC's power ...
    (rec.audio.tubes)
  • Re: P2B-DS and generic slotkets
    ... The slockets are labeled "Cpu Card ... processors are requesting 2.0 volts instead of 1.65 volts. ... If R3 is a 56 ohm resistor, ... With regard to the voltage being requested, ...
    (alt.comp.periphs.mainboard.asus)
  • Laughing even louder at the "engineers", thanks Old Hack Re: He who laugh last, laughs loudest, was
    ... if you look at the LM675 spec sheet it shows 90db of power supply ... If the power supply voltage varies ... going to get 60 volts peak-to-peak out, which is about 20 volts RMS ... So this added resistor has used up all the IC's power ...
    (rec.audio.tubes)
  • Re: P2B-DS and generic slotkets
    ... processors are requesting 2.0 volts instead of 1.65 volts. ... If R3 is a 56 ohm resistor, ... With regard to the voltage being requested, ... you sure the slocket doesn't have a way to modify the VID ...
    (alt.comp.periphs.mainboard.asus)
  • Re: P2B-DS and generic slotkets
    ... processors are requesting 2.0 volts instead of 1.65 volts. ... If R3 is a 56 ohm resistor, ... With regard to the voltage being requested, ... The BIOS displays 1.5v - it's not very accurate, and appears to round up in 0.5v increments. ...
    (alt.comp.periphs.mainboard.asus)