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<blockquote data-quote="helotaxi" data-source="post: 2770004" data-attributes="member: 550915">No it doesn&#039;t because it&#039;s wrong.&nbsp; The order of priority for current supply is alt, cap battery.&nbsp; The alt is the source for all current in the car.&nbsp; When it is tapped out the voltage starts to drop and the cap *can* ease this drop to he point that the battery discharge voltage is reached.&nbsp; At this point the cap&nbsp; has done all it is going to do for this evolution of the current spike.Now if you want to start looking at the math behind why a cap is not everything (or really anything) it&#039;s marketed to be, do some of the math.&nbsp; You will very quickly realize that a 1F cap will be spent much quicker than a single cycle of a bass note.If you crunch the numbers for a capacitor, you will find that the usable charge in a capacitor (discharging from 14V to 12V the difference between alt voltage and battery voltage) is .5 amp seconds per farad.&nbsp; &nbsp; A single cycle of a 60hz note is 17ms.&nbsp; If you only had a single cycle of that 60hz note (pretty much never the case) and a 30A deficit (pretty small really when you consider that a 1kW amp will draw in excess of 100A for a hard bass note and a stock alt usually only leaves you with 30-40A to play with) the 1F cap would keep the battery from being tapped (in theory).&nbsp; Sound like a reasonable way to spend $100+?What about the hybrid caps advertising 20F?&nbsp; Wow, you&#039;ve moved up to a whole 10A*s of reserve and spent several hundred dollars.&nbsp; How about getting a battery that carries a high float voltage and has a reserve measured in amp hours rather than seconds for less money?</blockquote>

[QUOTE="helotaxi, post: 2770004, member: 550915"] No it doesn't because it's wrong. The order of priority for current supply is alt, cap battery. The alt is the source for all current in the car. When it is tapped out the voltage starts to drop and the cap *can* ease this drop to he point that the battery discharge voltage is reached. At this point the cap has done all it is going to do for this evolution of the current spike. Now if you want to start looking at the math behind why a cap is not everything (or really anything) it's marketed to be, do some of the math. You will very quickly realize that a 1F cap will be spent much quicker than a single cycle of a bass note. If you crunch the numbers for a capacitor, you will find that the usable charge in a capacitor (discharging from 14V to 12V the difference between alt voltage and battery voltage) is .5 amp seconds per farad. A single cycle of a 60hz note is 17ms. If you only had a [B]single cycle[/B] of that 60hz note (pretty much never the case) and a 30A deficit (pretty small really when you consider that a 1kW amp will draw in excess of 100A for a hard bass note and a stock alt usually only leaves you with 30-40A to play with) the 1F cap would keep the battery from being tapped (in theory). Sound like a reasonable way to spend $100+? What about the hybrid caps advertising 20F? Wow, you've moved up to a whole 10A*s of reserve and spent several hundred dollars. How about getting a battery that carries a high float voltage and has a reserve measured in amp [B]hours[/B] rather than seconds for less money? [/QUOTE]

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