Brian617 Posted October 4, 2013 Report Share Posted October 4, 2013 I've read a bit on the forum and have a couple of questions I'd love an answer to. The first question deals with a video found on this site showing a 1 F capacitor helping dynamic output while a much larger (30 F?) one makes little improvement. The second is one I've had for years seeing 16v and 20v rated capacitors when shopping. I've always been told get the 20v, they're "better", which makes sense from a more is better perspective. But if my thinking is correct, the higher rated capacitor doesn't reach it's full potential until charged to its rated voltage, while the lesser rated capacitor would reach it's full energy storage at a lower voltage. 1) I wonder if the apparent success of the 1 F capacitor tested over the larger one is due to the charging cycle needed after discharge? Is there any rule of thumb on how long it takes to charge from 13.4v to 14.4v per unit of capacitance with a stock alternator? It seems an upper capacitance limit may be practical for a system. 2) Is the measure of capacitance dependent on voltage? If a 20v 1 F capacitor is charged to 14.4v, does it hold the same energy as a 16v 1 F capacitor charged to 14.4v? Link to comment Share on other sites More sharing options...
Wicks Posted October 4, 2013 Report Share Posted October 4, 2013 "Bigger" capacitors are not always better. Capacitors need to be specified for their specific application to do their job properly. Look inside an amplifier, there are MANY different sized caps, all doing different functions. If one cap was best then every cap in the product would be the same. The voltage rating on a capacitor is simply a safety rating and states the maximum voltage that a cap can be charged to. 16V caps could be completely fine in a system that doesn't reach or go over 16V. Of course its always better to have plenty of headroom with voltage ratings. The RC time constant, also called tau, the time constant (in seconds) of an RC circuit, is equal to the product of the circuit resistance(in ohms) and the circuit capacitance (in farads), i.e. = R * C. It is the time required to charge or discharge the capacitor, through the resistor, by ≈ 63.2 percent of the difference between the initial value and final value. It takes 5 "time constants" to fully charge or discharge a cap. Energy in a capacitor= 0.5CV^2. Therefore yes a 20V cap and 16V contain the same energy when charged to 14.4V. The 20V cap just has the capacity to hold more energy, but if you never charge that high then both caps are similar. The 20V cap just gives you more headroom since you NEVER want to over-voltage an electrolytic cap! They can vent out gases and electrolyte and in some cases explode apart. Seeing as though alternators can produce voltage spikes and most voltmeters used in car audio only measure RMS, then you never see those voltage spikes. Therefore personally I'd lean towards the 20V cap. It's common in electrical designs to over rate your needed capacitor voltage rating by 2x. So if you're circuit operates at 12V, a 25V cap would be great for reliability. This post sent with 100% recycled electrons. 2004 BMW M3Mechman 280A 2 - XS Power XP30001 - XS Power D375 500F of Maxwell SuperCaps (soon to be 1000F) iPadMini2Dash mounted O-scopeAudison bitOne (Remote DRC MP) Highs Amp - PPI Art A404 Hertz HSK130 (HSK165 waiting...) DC Audio DC9.0K 2- DC Audio XL12m2LEGAL - 147.3dB @ 41Hz OUTLAW - 150.2dB @ 45Hz OUTLAW - 145.7dB @ 30Hz JUNE 2014 SOTM WINNER 2014 COLORADO PEOPLE'S CHOICE WINNER SOTM BUILD:http://www.stevemeadedesigns.com/board/topic/141656-wicks-e46-m3-build-bass-turbo-button-and-a-big-new-addition/page-68#entry2802026 Link to comment Share on other sites More sharing options...
1two3 Posted October 4, 2013 Report Share Posted October 4, 2013 What he said lol Car: 2000 Honda CRV Battery: XS Power D5100R Alternator: Stock 90A Head Unit: Pioneer DEH-X9500BHS Front Speakers: Alpine Type S Rear Speakers: JBL GTO 628's Wires: All Knu 4g. Soon to be 0g. Big 3 in 0g Volt Meter: SMD VM-1 Amps: Rockford Fosgate T400-2, T1000-1bdCP Subs: 2 SSA XCON 15's Sealed Tint: Privacy glass + 5% in the back and 25% in fronts Link to comment Share on other sites More sharing options...
bassman619 Posted October 5, 2013 Report Share Posted October 5, 2013 I've read a bit on the forum and have a couple of questions I'd love an answer to. The first question deals with a video found on this site showing a 1 F capacitor helping dynamic output while a much larger (30 F?) one makes little improvement. The second is one I've had for years seeing 16v and 20v rated capacitors when shopping. I've always been told get the 20v, they're "better", which makes sense from a more is better perspective. But if my thinking is correct, the higher rated capacitor doesn't reach it's full potential until charged to its rated voltage, while the lesser rated capacitor would reach it's full energy storage at a lower voltage. 1) I wonder if the apparent success of the 1 F capacitor tested over the larger one is due to the charging cycle needed after discharge? Is there any rule of thumb on how long it takes to charge from 13.4v to 14.4v per unit of capacitance with a stock alternator? It seems an upper capacitance limit may be practical for a system. 2) Is the measure of capacitance dependent on voltage? If a 20v 1 F capacitor is charged to 14.4v, does it hold the same energy as a 16v 1 F capacitor charged to 14.4v? yes u are right..the voltage is just a cap tha the u dont want to go above at all..if theyre both charged at the he same rate and volts then the theyll both be the same..but then the farads really in my opinion tell u how fast itll discharge and recharge. For example a 10 farad cap would discharge quicker than a 1 farad cap. But the brand comes in to play too. Cheap brands do the same with capacitor farad ratings as they do with amp watts.. they advertise peak not constant to fool the nube..some people will tell never to get a cap. And just to upgrade the alternator and install extra agm batteries. But the way I see it ..what can it hurt? I like caps and feel they help provide more voltage stability to my amp when hitting hard bass notes playing loud. Keep in mind you will get voltage drops when playing loud but as long as it doesnt dip low like 10v or less then ur alright. But just dont use a cap to keep from upgrading electrical.if u have enough watts you will need tk upgrade alternator and battery choices.. You need trunk space to get groceries and shit...bitches love groceries Link to comment Share on other sites More sharing options...
Wicks Posted October 5, 2013 Report Share Posted October 5, 2013 I've read a bit on the forum and have a couple of questions I'd love an answer to. The first question deals with a video found on this site showing a 1 F capacitor helping dynamic output while a much larger (30 F?) one makes little improvement. The second is one I've had for years seeing 16v and 20v rated capacitors when shopping. I've always been told get the 20v, they're "better", which makes sense from a more is better perspective. But if my thinking is correct, the higher rated capacitor doesn't reach it's full potential until charged to its rated voltage, while the lesser rated capacitor would reach it's full energy storage at a lower voltage. 1) I wonder if the apparent success of the 1 F capacitor tested over the larger one is due to the charging cycle needed after discharge? Is there any rule of thumb on how long it takes to charge from 13.4v to 14.4v per unit of capacitance with a stock alternator? It seems an upper capacitance limit may be practical for a system. 2) Is the measure of capacitance dependent on voltage? If a 20v 1 F capacitor is charged to 14.4v, does it hold the same energy as a 16v 1 F capacitor charged to 14.4v? yes u are right..the voltage is just a cap tha the u dont want to go above at all..if theyre both charged at the he same rate and volts then the theyll both be the same..but then the farads really in my opinion tell u how fast itll discharge and recharge. For example a 10 farad cap would discharge quicker than a 1 farad cap. But the brand comes in to play too. Cheap brands do the same with capacitor farad ratings as they do with amp watts.. they advertise peak not constant to fool the nube..some people will tell never to get a cap. And just to upgrade the alternator and install extra agm batteries. But the way I see it ..what can it hurt? I like caps and feel they help provide more voltage stability to my amp when hitting hard bass notes playing loud. Keep in mind you will get voltage drops when playing loud but as long as it doesnt dip low like 10v or less then ur alright. But just dont use a cap to keep from upgrading electrical.if u have enough watts you will need tk upgrade alternator and battery choices.. I quoted the capacitor time constant in my above post. t=RC The time of charge/discharge is directly proportional to the capacitance. Therefore the higher the capacitance, the higher the charge/discharge time. A 10F cap will take longer to charge/discharge then a 1F cap. A 10F cap holds more energy then a 1F cap so it makes sense that it would take longer to charge. Electrolytic caps are rated at a certain capacitance with a usual 20% tolerance. Cheaper caps will sit lower in that spec. Higher quality caps will be higher in the spec'd range. This post sent with 100% recycled electrons. 2004 BMW M3Mechman 280A 2 - XS Power XP30001 - XS Power D375 500F of Maxwell SuperCaps (soon to be 1000F) iPadMini2Dash mounted O-scopeAudison bitOne (Remote DRC MP) Highs Amp - PPI Art A404 Hertz HSK130 (HSK165 waiting...) DC Audio DC9.0K 2- DC Audio XL12m2LEGAL - 147.3dB @ 41Hz OUTLAW - 150.2dB @ 45Hz OUTLAW - 145.7dB @ 30Hz JUNE 2014 SOTM WINNER 2014 COLORADO PEOPLE'S CHOICE WINNER SOTM BUILD:http://www.stevemeadedesigns.com/board/topic/141656-wicks-e46-m3-build-bass-turbo-button-and-a-big-new-addition/page-68#entry2802026 Link to comment Share on other sites More sharing options...
Krakin Posted October 5, 2013 Report Share Posted October 5, 2013 I quoted the capacitor time constant in my above post. t=RC The time of charge/discharge is directly proportional to the capacitance. Therefore the higher the capacitance, the higher the charge/discharge time. A 10F cap will take longer to charge/discharge then a 1F cap. A 10F cap holds more energy then a 1F cap so it makes sense that it would take longer to charge. Electrolytic caps are rated at a certain capacitance with a usual 20% tolerance. Cheaper caps will sit lower in that spec. Higher quality caps will be higher in the spec'd range. Are there any pros or cons in running a 1F cap over two two 500μF in parallel or two 2F in series? Edit: For the comparison lets say it is already parallel from battery to amp, so the amount of terminations will stay constant. Krakin's Home Dipole Project http://www.stevemeadedesigns.com/board/topic/186153-krakins-dipole-project-new-reciever-in-rockford-science/#entry2772370 Krakin, are you some sort of mad scientist? I would have replied earlier, but I was measuring the output of my amp with a yardstick . . . What you hear is not the air pressure variation in itself but what has drawn your attention in the two streams of superimposed air pressure variations at your eardrums An acoustic event has dimensions of Time, Tone, Loudness and Space Everyone learns to render the 3-dimensional localization of sound based on the individual shape of their ears, thus no formula can achieve a definite effect for every listener. Link to comment Share on other sites More sharing options...
Wicks Posted October 5, 2013 Report Share Posted October 5, 2013 I quoted the capacitor time constant in my above post. t=RC The time of charge/discharge is directly proportional to the capacitance. Therefore the higher the capacitance, the higher the charge/discharge time. A 10F cap will take longer to charge/discharge then a 1F cap. A 10F cap holds more energy then a 1F cap so it makes sense that it would take longer to charge. Electrolytic caps are rated at a certain capacitance with a usual 20% tolerance. Cheaper caps will sit lower in that spec. Higher quality caps will be higher in the spec'd range. Are there any pros or cons in running a 1F cap over two two 500μF in parallel or two 2F in series? Edit: For the comparison lets say it is already parallel from battery to amp, so the amount of terminations will stay constant. Assuming you mean two 500,000uF caps in parallel. There are definitely pros and cons to using multiple smaller caps rather them one large one. Design engineers will use multiple caps for reliability purposes. If one fails, the others can take up the slack and keep the circuit working. Multiple smaller caps may have a lower resulting ESR (equivalent series resistance) which could help reduce power loss and voltage drop. In some cases a larger cap may have the better ESR. Depends on your needs. Always a good idea to check the ESR of your cap options before you purchase. You might use caps in series to increase your resulting voltage capability since caps in series can handle an overall higher voltage applied to them then a single cap. This really comes into play with super caps or ultra caps with voltage ratings of only ~2.7V. Caps have "ripple current" ratings. Sometimes your circuit requires a ripple current higher then one cap can handle. Therefore you use multiple caps to spread out the current between many caps which also increases the life of the caps. This post sent with 100% recycled electrons. 2004 BMW M3Mechman 280A 2 - XS Power XP30001 - XS Power D375 500F of Maxwell SuperCaps (soon to be 1000F) iPadMini2Dash mounted O-scopeAudison bitOne (Remote DRC MP) Highs Amp - PPI Art A404 Hertz HSK130 (HSK165 waiting...) DC Audio DC9.0K 2- DC Audio XL12m2LEGAL - 147.3dB @ 41Hz OUTLAW - 150.2dB @ 45Hz OUTLAW - 145.7dB @ 30Hz JUNE 2014 SOTM WINNER 2014 COLORADO PEOPLE'S CHOICE WINNER SOTM BUILD:http://www.stevemeadedesigns.com/board/topic/141656-wicks-e46-m3-build-bass-turbo-button-and-a-big-new-addition/page-68#entry2802026 Link to comment Share on other sites More sharing options...
Brian617 Posted October 5, 2013 Author Report Share Posted October 5, 2013 I appreciate the replies. I see now that capacitance is not the total amount of charge, but determines the amount of charge per volt. I also see that the rate of charging varies with the ESR of each particular capacitor, which can vary. Link to comment Share on other sites More sharing options...
bassman619 Posted October 5, 2013 Report Share Posted October 5, 2013 I've read a bit on the forum and have a couple of questions I'd love an answer to. The first question deals with a video found on this site showing a 1 F capacitor helping dynamic output while a much larger (30 F?) one makes little improvement. The second is one I've had for years seeing 16v and 20v rated capacitors when shopping. I've always been told get the 20v, they're "better", which makes sense from a more is better perspective. But if my thinking is correct, the higher rated capacitor doesn't reach it's full potential until charged to its rated voltage, while the lesser rated capacitor would reach it's full energy storage at a lower voltage. 1) I wonder if the apparent success of the 1 F capacitor tested over the larger one is due to the charging cycle needed after discharge? Is there any rule of thumb on how long it takes to charge from 13.4v to 14.4v per unit of capacitance with a stock alternator? It seems an upper capacitance limit may be practical for a system. 2) Is the measure of capacitance dependent on voltage? If a 20v 1 F capacitor is charged to 14.4v, does it hold the same energy as a 16v 1 F capacitor charged to 14.4v? yes u are right..the voltage is just a cap tha the u dont want to go above at all..if theyre both charged at the he same rate and volts then the theyll both be the same..but then the farads really in my opinion tell u how fast itll discharge and recharge. For example a 10 farad cap would discharge quicker than a 1 farad cap. But the brand comes in to play too. Cheap brands do the same with capacitor farad ratings as they do with amp watts.. they advertise peak not constant to fool the nube..some people will tell never to get a cap. And just to upgrade the alternator and install extra agm batteries. But the way I see it ..what can it hurt? I like caps and feel they help provide more voltage stability to my amp when hitting hard bass notes playing loud. Keep in mind you will get voltage drops when playing loud but as long as it doesnt dip low like 10v or less then ur alright. But just dont use a cap to keep from upgrading electrical.if u have enough watts you will need tk upgrade alternator and battery choices.. I quoted the capacitor time constant in my above post.t=RC The time of charge/discharge is directly proportional to the capacitance. Therefore the higher the capacitance, the higher the charge/discharge time. A 10F cap will take longer to charge/discharge then a 1F cap. A 10F cap holds more energy then a 1F cap so it makes sense that it would take longer to charge. Electrolytic caps are rated at a certain capacitance with a usual 20% tolerance. Cheaper caps will sit lower in that spec. Higher quality caps will be higher in the spec'd range. my bad I should have been more specific...I meant a lager cap will have quicker response once charged and in use...like it can respond to the voltage dips while in use quicker than a smaller one can You need trunk space to get groceries and shit...bitches love groceries Link to comment Share on other sites More sharing options...
bassman619 Posted October 5, 2013 Report Share Posted October 5, 2013 Also if you use a cap be sure to wire it to a distributor block..having multiple wires connected to the terminals on a cap can hinder it..i hate seeing a cap with 3 or 4 power wires coming out of it..you only need 1 power and 1 ground and 1 remote if applicable..unless u use that rockford 10f cap or something similar..cuz it pretty much has a distribution block built in...or if you do multiple caps than multiple wires are understandable..but then when you do multiple caps you probably spend enough money to where you could have just bought an extra battery or two instead..but thats all up to you bud...dnt let anybody tell you not to do something u want to do cuz at the end of the day its yours not theirs .. You need trunk space to get groceries and shit...bitches love groceries Link to comment Share on other sites More sharing options...
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