isolating farad capacitor

teknofix wrote: I am about to install an 8 Farad Capacitor parallel to Battery to improve my Audio system performance I have been reading forums about how to install an Farad Capacitor, everybody is talking about charging the capacitor thro' the 12v  bulb an installing as close to the Amplifier. That's all fine. The purpose of the Farad Capacitor is, smooth, bump-up and hold the stored voltage, they are rated up to 24 Volts.  Ok. lets say Battery voltage is : +12V before entering the Farad Capacitor, and it is bumped up to +16 Volts by the Capacitor, so there is a 4 Volt difference between Battery and the Capacitor, nobody mentions how to isolate the voltage difference between the batttery and the Capacitor, another words preventing bumped-up voltage by Capacitor going back to battery but intsted only going to amp. I think, This can be done by simply placing a high wattage rating Diode between the battery and Capacitor on the + wire , hence Diode conducts only one way, Voltage stored on the Capacitor will only go to the amplifier, and it will be blocked to go back to battery, but the battery will supply to the Capacitor.Anybody agree or disagree with me or any suggestions how to isolate the mentioned voltage difference ? Teknofix@bellsouth.net

A cap will not "bump up" the voltage. A cap will help to "smooth out" the voltage fluctuations like you mentioned but it will be about the same voltage at the cap as at the battery. It would actually be slightly smaller at the cap because of voltage drop due to the resistance in the wire but that is another story. Also, the voltage when the car is running will be around 13.8-14.4 volts for an average car. This would be about what you would expect to see on the voltmeter the cap has.

Now the Capacitors are MAGIC.   We should give up.

Probably around 13.4 until the diode shorts.  Then it will be 13.8.

Forget the capacitor. As I have written elsewhere (also dealing with an 8F capacitor), a cheaper small AGM battery will do far better. Caps are for looks only, and to provide certain people with a "non-value-add" income stream.

teknofix wrote: I am about to install an 8 Farad Capacitor parallel to Battery to improve my Audio system performance

This is yor first mistake. If you have not addresed the power source in your car (two guesses, and the first seven don't count), you are wasting your time and energy, thinking this is going to "fix" or "help" anything.

teknofix wrote: I have been reading forums about how to install an Farad Capacitor, everybody is talking about charging the capacitor thro' the 12v bulb an installing as close to the Amplifier. That's all fine.

First, it's a capacitor. JUST capacitor. Not a farad capacitor. Farad is the capacitance value.

teknofix wrote: The purpose of the Farad Capacitor is, smooth, bump-up and hold the stored voltage, they are rated up to 24 Volts.

Wrong. The purpose of a capacitor when installed in a system with an inadequate charging source (have you figured it out yet?) is to pad the profit margin of the dealer selling it to unsuspecting, uninformed and undereducated consumers.

teknofix wrote: Ok. lets say Battery voltage is : +12V before entering the Farad Capacitor, and it is bumped up to +16 Volts by the Capacitor, so there is a 4 Volt difference between Battery and the Capacitor, nobody mentions how to isolate the voltage difference between the batttery and the Capacitor, another words preventing bumped-up voltage by Capacitor going back to battery but intsted only going to amp.

Wrong again. The capacitor cannot output more voltage than it is connected to. If you are connecting it to a 12V source, that is the voltage you will read across it's terminals.

teknofix wrote: I think, This can be done by simply placing a high wattage rating Diode between the battery and Capacitor on the + wire , hence Diode conducts only one way, Voltage stored on the Capacitor will only go to the amplifier, and it will be blocked to go back to battery, but the battery will supply to the Capacitor.Anybody agree or disagree with me or any suggestions how to isolate the mentioned voltage difference?

I disagree. First, diodes are rated by current @ a given voltage, not "wattage". Second, knowing this now, any diode of sufficient current rating to pull amplifier current demands through, will be HUGE, and will probably require you to mount it securely to the chassis of the car, (as the heatsink) in literally a ½" hole. I might also mention to you the expense of said diode! (Expect $100 or more...!)

teknofix wrote: What happens if I place Diode between Batt. and Cap. as shown below : ? Batt = + 13.8 V ---------------I>I-------------I I-------------> +V  to Amp         Diode           Farad Cap

Nothing. The cap doesn't go in series as you have indicated in your diagram. It's a parallel connected device.

teknofix wrote: I know there will be 0.6V drop across the Diode, but what Will be the final Voltage at the Cap +  ( using 8 Farad Cap ) ?    A = 13.2V     B =  14.4 V    C =  14.6 V     D =   None  ?

First, it's .7V drop for silicon diodes, and about .3V for germanium diodes. (Not really sure who told you it was .6V...) So, in answer to your question, AND based on the illustrated voltage of 13.8V, your cap will be charged to 13.1 volts, using the most common diode material - silicon. It will be around 13.5 volts using the less common, and more expensive germanium. Again, using your diagram, what will be the voltage at your amplifier? Zero. Your amp will not even turn on.

teknofix wrote: I will let you know, after I experiment to find correct answer (awaiting ordered 8 Farad Cap)

You already HAVE the correct answer: You are $200 poorer (give or take), will see little to absolutely zero benefit for that $200 loss, AND have still not addressed the POWER SOURCE in your car. (Have you guessed it yet?)It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

I know...I know...!!!!  He needs a new _____________! Mr .I will send you a schematic as a "How To"...I bet he will send it for ...Oh...Lets say...$149.99...Off the top you have saved $50 bucks and countless hours of trying to explain why it will work in your situation...! I think im going to refer to caps as "anti-spark" from now on...!M.E.C.P & First-Class

Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

http://bcae1.com/capacitr.htm ......................... http://bcae1.com/chargin2.htm ........................................... Just some basics... Where in your readings did someone recommend adding a cap...?M.E.C.P & First-Class

Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

haemphyst wrote: teknofix wrote: I think, This can be done by simply placing a high wattage rating Diode between the battery and Capacitor on the + wire , hence Diode conducts only one way, Voltage stored on the Capacitor will only go to the amplifier, and it will be blocked to go back to battery, but the battery will supply to the Capacitor.Anybody agree or disagree with me or any suggestions how to isolate the mentioned voltage difference? I disagree. First, diodes are rated by current @ a given voltage, not "wattage". Second, knowing this now, any diode of sufficient current rating to pull amplifier current demands through, will be HUGE, and will probably require you to mount it securely to the chassis of the car, (as the heatsink) in literally a ½" hole. I might also mention to you the expense of said diode! (Expect $100 or more...!)

Third: The capacitor cannot output more voltage than it is connected to. If you are connecting it to a 12V source, that is the voltage you will read across it's terminals.

tommy... wrote: http://bcae1.com/capacitr.htm ......................... http://bcae1.com/chargin2.htm ........................................... Just some basics... Where in your readings did someone recommend adding a cap...?

Probably car audio dot com, online car stereo dot com or woofers etc dot com... Or... Wait for it... BEST BUY!!!! YEA!!!! I love those guys. So amsrt! You know how those guys are. And to the OP... Have you guessed what you are missing yet? All the hints dropped in my first post to you haven't helped at all?It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."