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  • Capacitor

    Well, i just thought of this idea, instead of me using a relay and wiring the main power wire directly to the battery, could i possibly wire up the relay to the capacitor i have in my car, it is a one farad, and then hookup my blue wire from my amp, which is the amp turn on wire. also should it be able to survive crank, since technicaly one farad should be enough power to power the invertor while cranking and once crank it will get the power from the battery which is conected to the battery via 4 agu power wire

  • #2
    This has been furiosly debated. I am sure that you havn't done a search for it on this board.

    Just a heads up. People don't give out freebies here. They will just tell you to search especially when this has been covered alot in many threads.

    You should learn to use the search function. It is very helpful and accurate.

    Just trying to save you some trouble. The answers are out there but don't expect to be hand fed

    Cheers
    -Jesus- King of Kings Lord of Lords

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    • #3
      V2 = V1 * e^(-t/(R*C))

      You read this equation like this: the expresion with the e gives you the percentage of voltage you have after an ammount of time t given a resistance and a capacatance. with a time of 0 you get 100 percent.

      This is the equation for sizing a cap. You model your load with a resistor. A 4 ohm resistor is about a 3 amp load or a computer that draws 3 amps.

      t is time in seconds.

      R is the equiv resistance of the computer (4 ohms = 12v/3amps)

      C is the capacitance in Farads. (1 F)

      V1 is the voltage of cap at time zero. (12v)

      V2 is the voltage of the cap after time t. (11.5V)

      So say you go from 12 volts down to 11.5 volts without causing a hickup.

      Solve the equation for t and you get how much time a 1 F cap buys you.

      -Jeff
      MPEGBOX - Plexiglass Computer
      www.mpegbox.com

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      • #4
        and in case you dont know how the search button looks like

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        • #5
          zootjeff, that is the best explanation I've read =)
          New Lilliput EBY701 For Sale http://www.nusantech.com/index.asp?c...at=TOUCHSCREEN
          SiRF3 Bluetooth GPS http://www.nusantech.com/index.asp?cat=GPS

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          • #6
            alright i am sorry if i ****ed of someone, i tried to search, but only found one post where someone recommended a 4300 uf, cap to someone else.
            the only reason i ask, is i have a rockford fosgate cap for my system, "zootjeff" thanks for that kick *** post, i would do the math but my calculator (ti-83) is not here, also i was wondering on my cap packaging it says on there it is 16v and the monster cap which i didn't buy was 20v. i wish i had my multimeter, but since i moved from dallas to the boonies, i have misplaced my multimeter so i could measure right of the cap. If someone could do the math for me, at 12v and one at 13.5 and one at 16v. i will pray that you have many pleasure's in your life

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            • #7
              Capacitor only states its maximum charge voltage. It could be 100V and it would not make any difference. Maximum voltage is not to be exceeded. Since in a car voltage should not go above 14.5 Volts, a 16V Cap would work well.

              With a fully charged battery, your cap should get about 12.3 Volts with the car off.

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              • #8
                Originally posted by faiz_23
                i would do the math but my calculator (ti-83) is not here
                basic algebra shows:
                -(R*C*ln(V2/V1)) = t


                The above example shows that a 1 Farad cap with a 3 amp computer gives about 170 milliseconds of hickup protection. That assums that you have a diode, cause the starter moter could also be the load if you don't..

                You need an O-scope to know if 170ms is enough for you..


                Jeff
                MPEGBOX - Plexiglass Computer
                www.mpegbox.com

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                • #9
                  Wait a sec, my ti-83 wasn't here either. I used the calculator in windows. what gives?
                  MPEGBOX - Plexiglass Computer
                  www.mpegbox.com

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                  • #10
                    I must concure, I think some of us are getting a little lazy here.....

                    would you like a wiring diagram and maybe we could all come by and hook it up for ya too.....

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                    • #11
                      This has been furiosly debated. I am sure that you havn't done a search for it on this board.

                      LOL yeah...it cant be missed really. I have posted the equations about 3 times already before.

                      zootjeff...thanks for backing me up

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                      • #12
                        dug1967, hey if you want to come up here, more power to you, i will see to it that you will be reimbursed by a 12pack of beer, any taker, just kidding, well i found my multimeter and when the car is off i get about 12.3-12.5v, but for some reason when i hooked up the multimeter, i see it go from 12v down to 10.58 and then upto 14.3. so i guess it wouldn't work, because the starter pulls power from the battery and the cap, i guess i could use a diode, but how do you wire up a tiny little diode to a 4agu wire.

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                        • #13
                          i guess i could use a diode, but how do you wire up a tiny little diode to a 4agu wire.

                          please dont ask question like that

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                          • #14
                            you know what, screw all this, instead of using a standard capacitor, which most of us know doesn't work, lets try a flux capacitor, i will setup a group buy for all those intrested, pm me, so i know how many people want to buy one.

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                            • #15
                              I'm in. I've already got the 1.21GW generator.

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