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!!!! ](./images/smilies/eusa_wall.gif "Brick wall"){kind=small}
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~800 on an MR2, the battery voltage will be nearer 14.5v (Optimal Battery Charging voltage)... Unless you are some kind of SPL Monkey - you are unlikely to notice the difference... the dB scale is not linear with power...,, ! 
=D> 
... 12v-14v would not make any difference...(unless they have changed them recently) Many amps have unregulated power supplies....... and there is a SPL test with points!.. More volts in = greater power supply rail inside the amp = more power out... Fahrad CAPs, No matter what anyone tells you... do absolutely nothing... they certainly do nothing to stop lights dimming / maintain a higher voltage 
! paul port wrote:PS.
A lead acid battery can't cope with pulses of high demand.Stef Derner wrote:
I thought the only point in using large caps close to an amp is to be able to cope with high instantaneous current demand, the kind of thing a high power bass pulse might require.
.. a Lead Acid is more capable of supplying that current than a cap!(Especially the likes of an Optima!) have a very low output impedance and hold an awful lot of 'charge'...you learn a new thing every day! I've had some big installs in the past (not in MR2s) and have never had the need for a power cap.-*- Mk2 Turbo Rev2 -*- Mk1 NA -*- Mk2 Turbo Rev 3 = all gone!"Cruisey, Sporty, more innovation, more adult. A Man In Dandism. Powered mid-ship specialty."Nige wrote:I know this is moving slightly off topic now, but I haven't seen anyone on IMOC with a split-charge system for their big ICE installs to prevent the main battery from running down.
. or asking if anyone else had used a particular bit of kit. Damn my feeble memory.Nige wrote:Interesting.
I know this is moving slightly off topic now, but I haven't seen anyone on IMOC with a split-charge system for their big ICE installs to prevent the main battery from running down.
! Good install cant go without one ! 
Gareth Hill wrote:Nige wrote:I know this is moving slightly off topic now, but I haven't seen anyone on IMOC with a split-charge system for their big ICE installs to prevent the main battery from running down.
Ive got one
Got any pictures or info on your split charge setup?-*- Mk2 Turbo Rev2 -*- Mk1 NA -*- Mk2 Turbo Rev 3 = all gone!"Cruisey, Sporty, more innovation, more adult. A Man In Dandism. Powered mid-ship specialty."paul port wrote:Actually.
Consider what current is delivered when cranking the starter! a lead acid
The Amps power supply should contain enough input capacitance to deal with the power supply needs already
paul.
You can discharge a cap in microseconds without killing it, but if you short a battery, it will explode, or at the very least warp the plates, damaging it. A battery produces energy through a chemical reaction, which takes time. A cap holds a charge across the two plates and can quickly discharge and then charge again (relatively slowly) from the battery. Add the resistance of the wires and everything becomes slower. Unfortunately very little in life is built with quality over cost...(14.5v) to the battery (Who's source voltage is ~12v)(which is now a LOAD) - right up until the point you outstrip the alternator capacity, it's supply voltage under load falls to the same as the battery, at which point the Battery now becomes a SOURCE and provides the ADDITIONAL current required.= C dV(t) / dt Current through a capacitor is proportional to the rate of change in voltage across the capacitor(Manufacturer quote)/ Meter@ 12v, 5 Meters of 4Gauge cable, a 1Farhad Cap @ 12v, and your amp pulling 100Amps(is actually quite significant for crappy car 1F caps!)@ 100A+ 5x0.00096 = 0.0078 Ohms= 100 * 0.0078 = 0.78v(Ignoring the capacitors significant source resistance) the battery as the only other source (engine off) will then supply all current.-100A constant current flowing, the voltage across a 1F capacitor will drop by 0.78v in 0.0078 Seconds.... So, basically 7.8 milli-Seconds into your bass beat, the capacitor has become a load.'Good' capacitor like Stinger quotes source resistance around 0.0016Ohms, and this does not include connection resistance etc which all adds up... God forbid you buy a capacitor with a built in disconnect relay - as even a 40A Automotive relay has about 0.05Ohms contact resistance... Add up real world resistances, and you can see the capacitor becomes little more than install !!BLING!! and will do nothing useful for a bass beat - remember one cycle of a 50Hz tone lasts 1/50 = 0.02 Seconds - That is a long duration for any capacitor to deliver a high load for - and also a long duration compared to any chemical reaction in the battery.... DC-CD converter - and are not intended to supply any long duration load.(distorted) until the INTERNAL power rails fall below that required to deliver the expected voltage to the speaker load! Drive your amp within it's rated capacity with adequate cable and you won't have a problem. i bought one from ebay for next to nothing and at worst it wont damage my system. I have heard from my local ICE house, and quite a reputable one, that they are worth installing, but wont make a massive difference. A highbrid between the two, not heard anyhting bad about these!Neil_turbo wrote:The age old discussion on whether caps are good or bad will never be solved!!!
The future, maybe?!?!?, is in batcap.
Cheers
NEil
...Dina dina dina dina, dina dina dina dina... batcap, batcap, BATCAP!!!!!=oP