Wicks Posted December 13, 2012 Report Share Posted December 13, 2012 Caps don't hold enough power to be useful - even nice ones will be drained in a fraction of a second My DC5K has 24 1200uF caps in its power supply input which are used to produce >5kW. That adds to 28,800uF. Most basic stiffening caps are 1F = 1,000,000uF. Still think they're "small"? yes... still small.. the capacitors in that 5k's power supply section are not there to be the supply of power.. see snafu's post from before on how capacitors are used for many different purposes in electronics, from conditioning, to filtering, etc. Yes, I realize that and I'm not stating that the amp runs solely off of the input caps. They are there to reduce the ripple voltage to the power supply and stabilize the voltage. Stiffening caps are used for the same purpose at the input to an amp. I was merely comparing what a 5kW amp uses at its input to the actual size of most stiffening caps that people buy. 1F >>> 28,800uF. Caps in the trunk are not meant to supply power to the amp, they are to stabilize the voltage. Quote 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...
Brandon15zzz Posted December 13, 2012 Report Share Posted December 13, 2012 Ready to learn.....or teach. Quote Vehicle: 1995 Impala SSHead Unit: Pioneer AVH-P4400BHMids And Highs: (still deciding)Batteries: 1 Deka Group 34 Time to make a race car.My Build Log: Solo X 12"http://www.stevemead...don15zzz-build/My Build Log: DC lvl 4 xl 15"http://www.stevemead...don15zzz-build-My Wall Build Log: 4 Lanzar 15's/ 3k+ RMShttp://www.stevemead...t-by-techforce/My Feedback:http://www.stevemead...1 Link to comment Share on other sites More sharing options...
armykyle1 Posted December 13, 2012 Report Share Posted December 13, 2012 Not reading all the posts. Some people need to look into supercap setups. Bunch of 2.3v caps in series. It will stop ass Quote TEAM XS POWERTEAM HEAVY HERTZMy build- http://www.stevemeadedesigns.com/board/topic/194454-e46-bmw-build-pos/#entry2914134youtube- http://www.youtube.com/user/armykyle1big build starting Link to comment Share on other sites More sharing options...
zxsonnyxz Posted December 13, 2012 Report Share Posted December 13, 2012 Nice numbers Sanitarium, but it seems SO wrong! Can someone confirm my thought, or is it me that's in the wrong? Quote STD Passat Build 151db+STD Omega BuildMitsubishi Colt Build - Alpine|Focal|PeerlessHome Stereo BuildSmall Tang Band build - 4" fullrangeBox for 4 8"My Saab 9000 Build- I'd be very happy if you cared to check out the logs and give feedback! Link to comment Share on other sites More sharing options...
I.V Posted December 13, 2012 Report Share Posted December 13, 2012 This looks like a lot of headache ...lo Quote 06 Trailblazer ss2 Team shok industries tsx 18sPhoenix Gold ''THE ONE''2 Phoenix gold 800.44 crescendo mp6.2 crescendo mp8bass processor Dc power 270xp 150ft 1/0 ofc sky high cable1 juicebox lithium 0.5kwh 14v/40ahkenwood dnx8120BCAE1.com YouTube channel : REaudioxxx1build log: http://www.stevemeadedesigns.com/board/topic/160106-trailblazer-ss-xxx/ Link to comment Share on other sites More sharing options...
Wicks Posted December 13, 2012 Report Share Posted December 13, 2012 J=CV^2 (J= joules, C=capacitance, V=voltage) for a 1 farad capacitor on a system charging at 14.2 (voltage = random number somewhere around normal car voltage I pulled out my ass for the sake of this post) J = 1 x (14.2x14.2) J = 201.64 ok lets round that to 200 ok so 1 joule = 1 watt for 1 second. now lets play with those numbers. we all know amplifiers aren't perfect, power is lost to heat, etc. a pretty common number to see is 70% efficiency at 1 ohm on a class D amp. lets say you're the typical sort of SMD person. you want bass. you want it in your face, you like the long drawn out demo music, low notes, etc.. you stive for a big, powerful system. so lets start the number game at 5000 watts, at 70% efficiency, that amp needs 7142 watts of input. and remember from before, 1 farad = roughly 200 joules = 200 watts at 1 second. 7142 / 200 = 35.71 . round it up to keep from getting bogged down. 36 so that's 36 joules if the amp is operated for 1 second. lets keep playing with the numbers cause 36 farads is a ridiculous number for 1 second of play. say you put a nice single 275 amp alt under the hood, that charges at the 14.2 as we started this whole thing out at. wattage = voltage x amperage 275 x 14.2 = 3905 watts from the alternator bare minimum to run the car itself is say.. 60 amps or (60x14.2=852) call it 900 watts for overhead. so we got.. call it 3000 watts left for the system 7142 - 3000 = 4142 watts still needed for the system 4142 watts @ 1 second = 4142 joules / 200 = 20.71 call it 21 farads needed.. per second still haven't taken batteries into the equation here but we'll leave them out of this for now. ok so 21 farads per second, for 30 seconds of a bass race 630 farads. So who's buying me a 630 farad capacitor bank? This is some interesting math and don't get me wrong, I love working through some equations to figure out a problem, but it is assuming that you are running the amp totally from a capacitor so obviously you'd need a very large capacitor bank to operate the amp for any amount of time. Your math also assumes that you are completely draining the cap to ~0V. An amp can't really operate below ~9-10V so your usable voltage range is really only 14.2V to ~9V. 1 Quote 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...
Sanitarium Posted December 13, 2012 Report Share Posted December 13, 2012 This is some interesting math and don't get me wrong, I love working through some equations to figure out a problem, but it is assuming that you are running the amp totally from a capacitor so obviously you'd need a very large capacitor bank to operate the amp for any amount of time. Your math also assumes that you are completely draining the cap to ~0V. An amp can't really operate below ~9-10V so your usable voltage range is really only 14.2V to ~9V. very good that you point out these two things, 1. your battery doesn't provide very much juice above resting voltage so essentially as soon as you outrun youru alternator, your voltage starts dropping and you start draining the capacitor bank. 2 about the capacitors, as soon as the capacitors reach the resting voltage of the battery/batteries they then become neutral to the system, ready to draw from it as soon as voltage increases again, or provide power as soon as the demand grows, for a short while. so you can see for the purpose of pushing numbers around, putting these two things into the equation really just gums up the works and makes for more guess work in an otherwise clean exercise of throwing numbers at a board to see what sticks. 1 Quote Link to comment Share on other sites More sharing options...
Jessica Posted December 13, 2012 Report Share Posted December 13, 2012 (edited) I'm just curious how much current it takes to charge a cap per farad and how quickly they charge. I've never owned one, but everyone i know swears by them. But they all have stock charging systems and dimming headlights. Also, Can a capacitor help out with other things like the amplifier(s) for mid range speakers? Hopefully these questions get answered. edit: Also, don't things like capacitors start loosing efficiency as they get larger?, I mean, not only discharge time, but discharge vs charge time? Edited December 13, 2012 by strangeduck 1 Quote Rest in peace, walled 87 accord build log 03' Corolla build with AA Mayhem inside. My super random youtube channel and terrible camera work. Wiring comparison by CaptainzPlanetz Wire and fuse guide by Guest SyKo13 Link to comment Share on other sites More sharing options...
snafu Posted December 13, 2012 Author Report Share Posted December 13, 2012 Wow - we have some thinkers here . . . Quote Tony Candela - SMD Sales & Marketing Email me at [email protected] to learn about becoming an SMD Partner! Link to comment Share on other sites More sharing options...
8ight Posted December 13, 2012 Report Share Posted December 13, 2012 Wow - we have some thinkers here . . . Looks to me like you've inspired some thought! Quote I'm gonna hate Link to comment Share on other sites More sharing options...
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