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Silver Member Username: OlegSanta Monica, CA USA Post Number: 915 Registered: Nov-04 | Ok, so I do have an HO alt and a deep cycle batt. Now I want a cap. Why? So I can see how it works for myself, see the benefits, drawbacks, compare the system with and without it, etc So it was 1 farad per 1kW of dynamic power? Dynamic power of my system is probably are 4kW, but I'm going to get a 2F cap...that'll do? I know most caps are similar, but are there any recommendations as to the brand? Thanks!! |
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Gold Member Username: CtmikeCt. Post Number: 3994 Registered: Feb-06 | from everything i have heard it's 1 farad for every 1000wrms. as far as brands the most popular one i've heard of is stinger. |
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Gold Member Username: Nd4spd18Southeast PA Post Number: 1554 Registered: Jul-06 | For what it's worth: I've been into electronics in general for quite a while longer then I've been into car audio. When I first got into car audio, I once did the same exact test you are talking about doing. I already knew how electrical systems work, so I didn't expect the capacitor to make any difference, but my line of thinking was "if capacitors are so useless, why do they even make them?". I took a 500 watt system with a stock alt and battery, and installed a 1/2 farad capacitor near the amp. The result? I turned the system on and cranked up the volume, and what happened? Nothing. It sounded exactly the same as before, no audible change in loudness. Then I measured the voltage drop during long bass notes: no change. Then I turned on the headlights: they still dimmed. Now I think I realize why so many capacitors are sold, there are a a lot of newbs out there who are too cheap to upgrade their electrical systems, and WANT to believe that a $50 easy to install capacitor will solve their problems. |
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Silver Member Username: OlegSanta Monica, CA USA Post Number: 919 Registered: Nov-04 | Sounds interesting enough. I think this $40 experiment will be well worth the money. Do you think you would've seen different results if you had HO alt and deep cycle batt? |
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Platinum Member Username: GlasswolfWisteria, Lane USA Post Number: 11903 Registered: Dec-03 | the coke can caps are all the same. just make sure its got a low ESR, and if you want it, the volt display on top. |
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Gold Member Username: Nd4spd18Southeast PA Post Number: 1567 Registered: Jul-06 | I don't see why it would be any different. The alleged benefit of the capacitor is that it discharges energy very quickly. If it made no difference with a stock batt, then I see no reason why it would make a difference with a good battery (say a Kinetik), which discharges faster than the stock. The only potential benefit of a capacitor I've heard that sounds plausible is that it will "soften" sudden current demands, thereby extending the life of the alt's voltage regulator. However, I have not been able to find any research or data to back that up. |
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Platinum Member Username: GlasswolfWisteria, Lane USA Post Number: 11907 Registered: Dec-03 | misconception about capacitors. a cap's voltage mirrors the circuit voltage. if the alternator can't keep up and the voltage rails sag, so does the cap's voltage rail. this is essentially why cap's can't replace the need for an alternator. now that being said, if the alternator can maintain voltage where it belongs, with reserve current, then the capacitor serves two purposes: it acts as a filter for AC ripple produced by the alternator and not filtered adequately by the regulator, and the cap can reduce propagation delay or response time for the voltage regulator and alternator for peak demands. |
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Silver Member Username: KillswitchjdPost Number: 410 Registered: Apr-06 | so it would help with a ho alt basically |
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Silver Member Username: OlegSanta Monica, CA USA Post Number: 921 Registered: Nov-04 | The digital display on the cap indicates the circuit voltage, right? At those "spikes" I should see the voltage drop? BTW what's a low ESR rating? Also, i have few more questions... 1. Since i'll have a dist block, should the cap be before the dist block or should it be after and just dedicated to the sub amp? 2. my audiobahn amp's rated at 2400W rms (for subs) and my JBL is about 400W rms (mids/highs) so i need 2.5F cap? |
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Gold Member Username: N2audioLawrence, Ks USA Post Number: 1257 Registered: Mar-04 | "if capacitors are so useless, why do they even make them?". If you could build an item for $10 that didn't really do anything for anyone, but hundreds/thousands of people would pay you $50 for it would you stop making them?? |
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Silver Member Username: OlegSanta Monica, CA USA Post Number: 923 Registered: Nov-04 | lol i see the business point of this in car audio how bout my questions?? |
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Silver Member Username: OlegSanta Monica, CA USA Post Number: 924 Registered: Nov-04 | If it's one like this, with 2 "cans" lol it still only needs 1 power cable, right? http://cgi.ebay.com/POWER-ACOUSTIK-PCNC-2F-3-Farad-Car-Audio-Capacitor-Cap_W0QQi temZ220103027457QQihZ012QQcategoryZ75388QQrdZ1QQcmdZViewItem Or is this one better because it actually states the ESR rating? http://cgi.ebay.com/NEW-07-PYRAMID-3-Farad-Digital-Car-Audio-Capacitor-Cap_W0QQi temZ220101508731QQihZ012QQcategoryZ75388QQrdZ1QQcmdZViewItem |
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Gold Member Username: Nd4spd18Southeast PA Post Number: 1618 Registered: Jul-06 | ESR = Equivalent series resistance. Less is better. I would install it as close to the sub amp as possible, but I'm not sure how much it matters..... |
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Silver Member Username: OlegSanta Monica, CA USA Post Number: 925 Registered: Nov-04 | so i shouldn't use it for the jbl then, right? and what size do i need? 2.5F or 3F? |
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Silver Member Username: KillswitchjdPost Number: 415 Registered: Apr-06 | careful with those ratings, the ones that are 10, 15, 25, 50, 100 and rediculous sh*t numbers like that are what I thought was called batcaps. But they suck anyways... Yes, get either 3 or 4 farad for this "experiment". and fills us in asap |
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Silver Member Username: OlegSanta Monica, CA USA Post Number: 929 Registered: Nov-04 | thanks, i'll go for the 4F probably. i'm getting it all installed at the same time, probably Sunday. I'll post my findings. |
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Platinum Member Username: GlasswolfWisteria, Lane USA Post Number: 11910 Registered: Dec-03 | put the cap as close to the amp itself as possible (in the circuit) usually between the dist block and amp you really only need the cap on your sub amp(s) the full range amp for the mids/tweeters usually doesn't see sudden large demands for three times the RMS power like sub amps do |
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Silver Member Username: OlegSanta Monica, CA USA Post Number: 931 Registered: Nov-04 | So I'll also get a DMM then, too. To make measurements across the circuit, I just need to measure it at one point like the positive battery terminaly? |
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Platinum Member Username: GlasswolfWisteria, Lane USA Post Number: 11914 Registered: Dec-03 | depends on what you want to measure. you can read at the battery and at the amplifier and compare if you want to see voltage drop |