twonks

My Octavia VRS (Petrol) is due in August , and I intend to put my own stereo system in.

I've been told that on most new cars that run Can Bus, like the Octavias, I will need to reprogramme the main cpu (I presume) so it knows to expect a large current draw from and allows the alternator to cope with it.

As the current draw of my amps will be around 60A - 80A at full tilt, does anybody know if I need to reprogramme anything or will the car self learn and teach itself that the large draw is not a fault?

Thanks.

TeflonTom

it willbe the alternator that's struggling to cope... might be worth fitting a large capacitor in series with the battery near the amplifier to smooth out the massive battery discharges

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twonks

Thanks for the reply.

tbh I've been into car audio for years and know all about current draw and alternator capabilities etc, and caps are not really any good apart from show.

I think the factory electrics will be able to cope, although I may do the big three under the bonnet.

I was mainly concerned just with this canbus issue and whether the cars electrics would sense that the excessive current draw would shut something down as it thought there was a fault - ie dead short somewhere etc.

Lummox

It wont do and there isnt anything you can really reprogram anyhow.

There is a system built into the car that should current draw exceed battery and alternator output is will selectively start shutting things down to limit barrety drain. But providing the battery and alternator are able to cope you wont have a problem.

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TeflonTom

they do look nice... but isn't that what it's all really about anyway???

oh and... the capacator is in parallel with the battery, not series like i said above.... phew! brain not switched on today yet

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twonks

Thanks Lummox.

This makes my life a little easier

twonks

Capacitors are really only any good where you have a single excessivley large current demand every once in a while.

As car audio and music usually has constant beats and very quick succesive need for current, all the cap will do is charge up before the first then essentially act as a large piece of cable. The reason for this is that it won't have time to charge before the next bass hit.

As for looks, well my system is mainly hidden from view, apart from the head unit. Stealth is more the thing then c.hav esque looks for me

TeflonTom

that's not what a capacitor is there for... it's there to just smooth the voltage out, if you place too much demand on the battery/alternator the voltage will drop...

i think of it as a buffer, rather than expecting it to solely supply all the required current

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twonks

I agree about the voltage and demand thing, but capacitors do not belong in the power train of car audio

I don't want to get into an argument with a long standing member of BriSkoda, especially as I haven't even got a Skoda yet lol, however if you want to read about what is generally thought regarding capacitors, have a look over at talkaudio.

I'll leave it at that as my original post has now been answered.

Thanks all

TeflonTom

i hate them... if you ever taken a battery terminal off a car not realising it has a capacator fitted you can get a nasty bolt from it... it's not something i can recommend

i'm just a newbie..... i will check out talkaudio

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tfboy

A decent car battery will have a shed load more instant power available from it than any cap ever would!

Unless you're into silly power with class A/B amps, I think you would be OK. The big issue is when people who compete in SPL events with 1.0 corsas expect small capacity batteries and alternators to cope with well over 100 amp currents.

Not an issue with a modern decent sized car such as the octavia IMHO

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