i think i may have a weak alternator but not sure, not sure if this is in the right place either :confused:

i have noticed over the last few months a strange thing happening when i flash people through, if i flash while stationary(i.e. not revving) then my front speakers dip for a second. all my speakers are amped and off an aftermarket stereo.

i have also noticed since installing a new pair of speakers that if i play a track with strong deep base(like dre for example) at a decent volume then they keep cutting out too.

i think i may have a weak alternator, is there an easy way for me to test my alternator :confused:

alos does anyone know which alternator i will have on my car as there are three different ratings listed fo rthe octavia, a 70A, 90A and 120A(i think thats right) :confused:

thanks in advance

The UK-spec 4X4 is normally fitted with the 90A alternator. This is listed as 8GD in the primary option codes for the Octavia. 8GL is the 120A alternator and 8GM the 70A one. See the following thread for more Octavia codes:

http://www.briskoda.net/forums/showthread.php?t=2954

might look into this then, others have suggested battery. skoda did have trouble charging it so for now i'm gonna nick the battery from the nova seeing as its new and a heavy duty diesel battery

Do you have a volt meter?

Try the battery voltage with the engine switched off.

Start the engine and the voltage should go up to around 13 to 14 Volts. Switch on every thing you can think of, lights heated screen etc. The voltage should still be above 13volts ish and should go up to the original voltage with a few revs. If it does the alternator is OK.

You could have a duff battery but this usually shows up with not being able to start the car in a morning.

What I suspect is you have a wiring or connection problem. You probably have a section of wiring, connection or bad earth that struggles to flow the current when high demand is taking place (Like flashing your lights or a deep bass sound)

I'd start by checking the size of cable and connections to your amps(Positive and earth). Where are your amps connected?

At the end of the day if you have a mega sound system a standard car electrical system will struggle to cope. I used to run around 3000W with 3 subs. The headlights would dim along with the bass notes. I ended up running a liesure battery and split charge system. Now days a lot of people use capacitors but haven't tried them myself.

Cheers

Lee

i have two 300W rms dvc subs, components up front and all running off seperate amps, the stereo is wired in zero gauge live and earth with a power cap back there too. nice solid earth bolted on with the seatbelt under the seat. gonna go test the alternator in a minute to see what i get, this should be done with the engine running?? :confused:

i have two 300W rms dvc subs, components up front and all running off seperate amps, the stereo is wired in zero gauge live and earth with a power cap back there too. nice solid earth bolted on with the seatbelt under the seat. gonna go test the alternator in a minute to see what i get, this should be done with the engine running?? :confused:

Yep,

Battery Voltage should be a touch over 12V, start the engine and you should see 13V upto around 14.2V as the alternator charges. Put the alternator onload by turning on all the lights and heaters and maker sure the voltage is still up above 13V. Rev the engine a little and the Voltage should be up nearer 14V.

Cheers

Lee

i have two 300W rms dvc subs, components up front and all running off seperate amps, the stereo is wired in zero gauge live and earth with a power cap back there too. nice solid earth bolted on with the seatbelt under the seat.

Where are the amps positive cables connected, direct on the battery or rear of the fuse box?

Cheers

Lee

straight onto the battery.

i just went out and it turns out that my test equipement doesn't work on 12v :( only mains sadly

but i did go and change the batery with the one on the now dead nova which is a heavy duty 66AH battery compared to the normal 60AH slightly dodgy battery on mine and it seems to have helped, can now run the stereo louder without it cutting out but it does still cut out when i put it upto what i consider loud on tracks with heavy base.

i think i will see how much the 120A alternator is and maybe get prices from breakers, would the same alternators be used on VW/AUDI etc?? i personally would have thought so but not sure.

anyone know of prices??

It does look like you are getting volts drop on high current consumption. Your amps protection circuit is cutting in and that's why you are loosing the sound.

It will still be worth checking your alternator and all the amplifiers wiring as well as the capacitor wiring. I would even try it without the capacitors and see what happens.

A larger capacity alternator will help but you are not flattening your battery so yours is still providing enough charge to run the car and a bigger alternator may not provide that instant reserve of current you need when the bass goes ooomph.

You may want to try a big TDi Octy battery and see how that goes or setup a split charging system and have an additional battery or even try bigger capacitors.

Depends what you can rig up or borrow I suppose.

Just as a passing thought, make sure all the cars battery and earth connections are good. Sometimes the manufacturers earth point onto the body isn't upto running large current dragging circuits. Not looked at the Octy's though.

Cheers

Lee

was thinking of the battery from a tdi L&K

the wiring is fine, only went in a few weeks ago and have changed the speakers since then.

next thing to try is removing the cap fomr the circuit

just got a price of a new 120A alternator from the local stealer

about

Sounds about right, those things aren't cheap

have spoken to my local friendly shop and found an aftermarket 120A item for around