Dimming Lights

[whitevrboi]

Just wondering how much power is needed from a sub and amp in order to dim the lights? I only have one 400wrms sub running of a 400wrms amp and my lights dim with bass line even when the volume is at half.

My battery is near new. not sure what size power cable i am running...came in a installation pack from straty car radios, could my alternator need adjusting or should i get a bigger one?

any help would be great. cheers jack

[VSIIBerlinaL67]

i have the same problem very annoying

[daron]

if your power cable is to small you will get dimming lights
find out what size it is

[VrWagz1]

Also, you can reduce this a fair bit by making sure your battery terminals and clamps are clean. Plus if you have just earthed your amp to the car, did you bolt the lug down good to a good shiny peice of steel, not just a self tapper in the floor over the paint.
The other big thing i see heaps that can cause this problem, if you earthed your amp to the body, is not upgrading the wire that goes from the body to the battery - terminal, they spend all day running a big amp wire but only have a tiny cable going from the battery to the body. these few things should help reduce light fade to a minimum, but you will never fully stop it.

[Phreddy]

Let's think about this logically - if the power feed wire for the amp is too small, or the ground for the amp isn't too good, how would that cause the headlights to dim?? It's on a completely separate circuit from the battery, so even if there was a voltage drop along that cable / ground point, that voltage drop would only be affecting the amp, not the headlights.

Check the ground from the battery to the chassis certainly, if the voltage drop is occurring there then that would cause the problem, otherwise I would recommend getting the alternator checked out. Also, bear in mind that at engine idle speed the alternator won't be producing all the current it's able to. Do the headlights still dim down when you bring the revs up to say 2000rpm??

Cheerz.

[pugga]

i get dimming lights also, i run 0 gauge for ground off the battery and run it to the boot, using a 1 farard cap and a heavy duty battery,

I would upgrade the battery to a optima and check all your wiring is grounded.

[Haydz]

upgrade your engine bay wiring to something like 4 gauge. engine to chasis etc.
also a dodgy alternator/battery clamp combo could be causing your head lights to dim

[DarkCrystal]

You won't need a cap unless you are running some mega mega big sounds... you'd be fine for well over 1500wrms...
I have a VT and also get the dimming lights, even at half volume... i'm running 2 amps, one at 1100wrms and one at 400wrms total power - so total of 1500wrms...what iv'e been told to do is increase the size of the charge wire from alternator to battery - this should fix the problem... i'm gonna do this this weekend... let ya's know how it works out...
Also, suss out the current draw of your amp/amps to ensure that your power wire can handle it...

[TMM]

Beef up the ground cables

[whitevrboi]

I think the prob may be my grounding as i only scraped away a bit fo the paint when i was grounding the amp. i'll check the grounding for the battery and also if my headlights dim at a higher rpm.

I heard somewhere that you can get the brushes in your alternator changed/fixed/aligned? has anyone else heard of this?

I'll change my cabling to something a bit bigger and see if that helps. thanks everyone who has given me their advice.

[Flat_White]

I use 8Gauge and this happened to me, i used a better grounding point and problem was solved.

[VrWagz1]

Let's think about this logically - if the power feed wire for the amp is too small, or the ground for the amp isn't too good, how would that cause the headlights to dim?? It's on a completely separate circuit from the battery, so even if there was a voltage drop along that cable / ground point, that voltage drop would only be affecting the amp, not the headlights.

Check the ground from the battery to the chassis certainly, if the voltage drop is occurring there then that would cause the problem, otherwise I would recommend getting the alternator checked out. Also, bear in mind that at engine idle speed the alternator won't be producing all the current it's able to. Do the headlights still dim down when you bring the revs up to say 2000rpm??

Cheerz.

If you think about it logically, yes it will dim the lights, because if you lose voltage on the amp cct then it obviously has to draw more current to make up for the voltage loss. And as your current draw gets higer, cables and connections get hotter and resistance continues to increase thus lowering the voltage even furthur to say 7volts temporarily, especially on high current draw of a bass note. Now that you have all this great extra current draw (almost double on a bass note, due to the voltage being nearly half), it starts to take its toll on a standard battery, as it will now drop 2-3 volts when these higher currents are drawn out of it, There is reason for that too, but thats another story

[immortality]

shuldn't fitting a CAP help with the big bas notes to maintian voltage. i also agree with checking the main charge cable from the alt to battery. even in stock standard cars these fail and are really a little small for peak loads

[kopper69]

shuldn't fitting a CAP help with the big bas notes to maintian voltage. i also agree with checking the main charge cable from the alt to battery. even in stock standard cars these fail and are really a little small for peak loads

Well, yes and no. Thats what a cap is designed to do - supply the current for that big punch when the battery cannot. It depends though - you may have a dying or insufficient battery, loose terminals on the battery etc. There are situations where a cap will fix the problem, but there are also situations where a cap will only make the problem worse.

[immortality]

Well, yes and no. Thats what a cap is designed to do - supply the current for that big punch when the battery cannot. It depends though - you may have a dying or insufficient battery, loose terminals on the battery etc. There are situations where a cap will fix the problem, but there are also situations where a cap will only make the problem worse.

true, i was working on the assumption that said people had their electrical systems up to scratch which would generally include checking connections, upgrading the main battery to chassis earth link to cope with stereo system etc

[whitevrboi]

ok well i have a near new battery but stock cables from alt to batt and from batt to chasis and my terminals are all good and tight. i'll change my amp grounding and upgrade my enigne bay cables and see if that helps. can anyone suggest a good grounding point in the boot of a vr? cheers everyone

[immortality]

ok well i have a near new battery but stock cables from alt to batt and from batt to chasis and my terminals are all good and tight. i'll change my amp grounding and upgrade my enigne bay cables and see if that helps. can anyone suggest a good grounding point in the boot of a vr? cheers everyone

i would also upgrade the battery to chassis cable as this need to cope with all the other electrical items that earth through the chassis let alone the stereo install

[Denno]

Hey guys, I have this same problem. I was talking to a mate and he suggested that my earthig wire is too long? Is this a possibility? I have a 4ga wire running to my amp from battery, and the ground is aother 4ga wire straight back to the battery, so the earthing wire is around 4m long.. Don't ask me why I have done this, just let me know if it's the problem or not Thanks.

[whitevrboi]

ok so i fixed up my earthing from amp to chasis and that has made a huge difference. I am also going to beef up my other cables as i plan on gettin another sub soon so it'll save me from doing it later on. thanks for all your help guys.

[VrWagz1]

Hey guys, I have this same problem. I was talking to a mate and he suggested that my earthig wire is too long? Is this a possibility? I have a 4ga wire running to my amp from battery, and the ground is aother 4ga wire straight back to the battery, so the earthing wire is around 4m long.. Don't ask me why I have done this, just let me know if it's the problem or not Thanks.

That should be ok, a slong as the cables are rated for the amount of current the amp is going to draw, then there is no issues there.

[/QUOTE] ok so i fixed up my earthing from amp to chasis and that has made a huge difference. I am also going to beef up my other cables as i plan on gettin another sub soon so it'll save me from doing it later on. thanks for all your help guys. [/QUOTE]

Good to see its all fixed up then

[Denno]

That should be ok, a slong as the cables are rated for the amount of current the amp is going to draw, then there is no issues there.

So if that's ok, then that mean I wouldn't have the same problem as whitevrboi. Could mine be alternator? Or what else could contribute to this problem? I have only really read upgrading the wire between the battry negative and chassis, which doesn't apply to me..

[Chirpstr]

Mine does this so annoying. The reg seems to be putting out a nice ouput...duno what is causing this. Running 2 subs and one amp atm. Lights dim and people thinking I'm flashing them. Maybe it's going come down to getting a cap...

[VrWagz1]

So if that's ok, then that mean I wouldn't have the same problem as whitevrboi. Could mine be alternator? Or what else could contribute to this problem? I have only really read upgrading the wire between the battry negative and chassis, which doesn't apply to me..

If it is really bad, i would suggest you try joining you 2 power wires you ran to the amp together. Then hook them both up to the + on the battery and amp. Upgrade your wire to the chasis and the battery -, and ground your amp with a bigger cable to the chasis, in a good clean, paint free spot prefferably under a bolt head not a screw. That shouldn't take long and a quick way to check to see if your cables were causing the problem, as you have now almost doubled the size of your power cabling.

[VrWagz1]

Mine does this so annoying. The reg seems to be putting out a nice ouput...duno what is causing this. Running 2 subs and one amp atm. Lights dim and people thinking I'm flashing them. Maybe it's going come down to getting a cap...

So you have taken your battery leads off and cleaned them up and checked your earths, upgraded the batt - to chasis wire. Have you tried running a bigger cable temporarily from the battery to the amp to test its not an under rated cable. Is your battery a decent sized battery, if you have replaced it with a smaller battery at some stage then it maybe undersized for 2 decent subs.

[TMM]

A cap will make matters worse if the problem is insufficient grounding.