Headlights dimming when volume turned up?

[jgi420]

So I've had a new system for about a year.

 

I have skar evl12s two of them and I have the rp2000d amp I also have a small door speaker amp. 

 

I noticed at night when I'm driving around In the bass hits my headlights dim. Now I know the maximum level of playing volume is different for different head units different people ect. 

 

My head unit seems to like to play clean around 21 to 24 volume. It was like this on the last two amps. 

 

The skar doesn't have a clip light Like the nvx amps do. I have the gain on the amp  set at about 3/4 of the way up.

 

Now a few of you might have seen me post in here and might remember What? I had going for a system and specs but some probably do not so I can briefly go over my setup.

 

One of the first things I did even when I had a stock alternator was the big three I ever since upgraded and did the big four and now I have an aftermarket alternator. I have a 250 amp js unit I've got one of the grounds on the alternator ect.

 

The main power wire going to the battery has a 150 amp fuse It never blows. 

 

I got a distribution block in the rear which is fused and that never blows either. 

 

I have a piece of 4 gauge ofc silver tinned Going to The monoblock subwoofer amp. 

 

I have recently replaced my battery because my original battery was 5 years old and failed. So around 2 months ago I picked up an EverStart Max Which is 800 cranking amps nothing super fancy but it starts the car. 

 

So basically my main concern is that I might not be receiving full power from the amp or that the sound quality might not be as good. Seems like with the Alpine head unit I have I turn the volume up to 18 or 19 and with certain songs and music, the headlights start dimming when the bass hits. 

 

Now I have general knowledge about electricity but I'm no electrician. I've had a few systems hadn't dealt with dimming too much.

 

I have a Grand Marquis Now I do realize that some of these cars have a lot of electronics and if you have a lot of things running You could be taxing your electrical system. 

 

I don't always crank my heat and I don't always crank my air conditioning when it's hot out yet I still get the dim. I thought about maybe turning off daytime running lights so my headlights wouldn't stay on during the day when I didn't need them and maybe that would help. My vehicle draw less but I haven't messed with that.

 

The only thing that I can think of is maybe the position of my subwoofer amp ground Is not in a good location or running my heat When it is cold out or using the AC when it is warm out cranking everything maybe the alternator can barely keep up. 

 

I have always been told that a vehicle is never going to use its full amount of alternator power all the time. 

 

The only way I could see my alternator being fully taxed is if the car is trying to draw 100 amps itself without the stereo running and then when you turn on the stereo that is requiring around 140 amps. Then maybe I would be close to exceeding my alternators output but I'm just not seeing anything that's adding up. 

 

I was considering grounding my amplifier to the frame which would mean I would have to drill a hole in my trunk somewhere and try to get my ground wire to reach to the frame. Then I would have to clean the area on the frame to get a good connection. But I was also thinking that you now have 4 ft of ground wire instead of two which would cause more resistance. I would also need a new piece of wire that is longer. 

 

I will post a picture of the ground wire and the way it's set up now as you can see, it's located  right next to the passenger side trunk arm

[Joe X]

You need a HO alternator and a deep cycle battery to run a 2K amp, big 3 and proper wiring to the trunk are also necessary.

 

Otherwise you are going to keep blowing batteries and at some point the stock alternator will blow as well.

 

One trick to reduce current draw is using the amp subsonic filter setting it to 30Hz, this does not fix the issue, just lessen the side effects.

[Kyblack76]

Doubt your making half the power you think you are.  Your js 250 should be doing fine, but any drop, like a tenth,  will dim old shitty halogens.

Put led in and that will cure that.  A alternator, will absolutely make full out put, IF, its demanded to. (also why your not popping your alt fuse)

  You could have 14.4vdc, and drop to 13.99 and old og bulbs, will dim. Healthy starting voltage or not. In fact, a better alt, can induce WORSE noticed dimming, because it chargers higher.  Does that make sense? But dimming issues, fast voltage drops, in a car, are so fast, the alt cant respond fast enough to remove that fast dip, and dim on the old bulbs. If your voltage is fine, then don't sweat the dimming. Part of the party.  LED's wont dim, regardless of drop. Due to their design.  

 

 

EDIT - Found a old vid.

1 Singer 320 clamped, just daily on music (not in the lanes letting it really rip on a tone). And i had 2. Both hair pins. And both would be taxed when i leaned on it. Never even looked or cared about my head lights. (old as fuck blazer, with old as fuck halogens) Never cared. 

 

 

[jgi420]

Well I guess that's pretty much probably what I've got going on. Just you know what a lot of people have said when you start running a lot of power your headlights will dim. Especially if they're old halogen bulbs like a few people said here. You know the only thing you can do is put in LEDs. 

 

And yeah I agree with the last poster. I'm probably I am probably not drawing that much. I don't know why though. When you watch some of these amp Dino videos they show RMS powers and on some of them it looks like they're pulling upwards of 200 to 240 amps Like on one video that I watched of the skar audio amp I saw where they showed an RMS burst at one home and it was pulling 240 amps. I don't seem to be drawing that much power. 

 

So from what's being implied here I should expect headlight dimming .

 

So far the only thing I did was turn down the gain level on the amp a little bit and now my headlights don't dim that much. 

 

I also tried to run the ground to the frame like someone suggested that I talked to and when I did that I had worse of a connection. 

I had resistance and I couldn't get the subs to play any music. So I put the ground wire back where it was by the trunk. 

 

And yes, when I checked the power going to the alternator before everything looks solid. It was almost no resistance and almost no voltage drop. 

 

So I guess for now I'll just leave everything alone

[jgi420]

On 2/24/2025 at 5:21 PM, Joe X said:

You need a HO alternator and a deep cycle battery to run a 2K amp, big 3 and proper wiring to the trunk are also necessary.

 

Otherwise you are going to keep blowing batteries and at some point the stock alternator will blow as well.

 

One trick to reduce current draw is using the amp subsonic filter setting it to 30Hz, this does not fix the issue, just lessen the side effects.

Yeah I got a big ass OFC 1/0g power wire going to the back to a distribution block and then I got a 4 gauge ofc piece of silver tinned going to the amp from the distribution block. 

 

And the alternator is either 240 or 2 50 amp from JS alternators. It's an aftermarket So I've already got an updated alternator. It's not stock. I haven't had stock in about 3 years and I just replaced The main starting battery 3 months ago I went from a Napa legend to an EverStart Max. 

[Kyblack76]

On 3/4/2025 at 1:48 PM, jgi420 said:

Well I guess that's pretty much probably what I've got going on. Just you know what a lot of people have said when you start running a lot of power your headlights will dim. Especially if they're old halogen bulbs like a few people said here. You know the only thing you can do is put in LEDs. 

 

And yeah I agree with the last poster. I'm probably I am probably not drawing that much. I don't know why though. When you watch some of these amp Dino videos they show RMS powers and on some of them it looks like they're pulling upwards of 200 to 240 amps Like on one video that I watched of the skar audio amp I saw where they showed an RMS burst at one home and it was pulling 240 amps. I don't seem to be drawing that much power. 

 

So from what's being implied here I should expect headlight dimming .

 

So far the only thing I did was turn down the gain level on the amp a little bit and now my headlights don't dim that much. 

 

I also tried to run the ground to the frame like someone suggested that I talked to and when I did that I had worse of a connection. 

I had resistance and I couldn't get the subs to play any music. So I put the ground wire back where it was by the trunk. 

 

And yes, when I checked the power going to the alternator before everything looks solid. It was almost no resistance and almost no voltage drop. 

 

So I guess for now I'll just leave everything alone

 

 

Amp dynos are a "reactive" load, not nominal, and why on those tests, you see all the amps, and all the power.  For you to do that real world, you would have to wire down to like .25, and even then,, a million factors come into play with load/resistance.  No idea what load you are presenting the amp (1ohm) but it can quadruple (and usually much more) with a moving driver, and on music not a tone, and such with the board, not making near, half the "MAX" power.   For a daily pounder, you are fine. The dimming can be annoying , but dem da breaks in this hobby.  Getting some source of knowing what your voltage is doing wouldn't be a bad idea. Some sort of meter. But if you pound on it driving, park it, and it cranks over the next day, chances are, your not killing your battery.  And remember, this is a 12v hobby. Dipping into battery voltage, isnt a horrible thing. If you see 9vdc, .. your running through batteries constantly,.. need a jump in the morning, the amp goes into low volt protect, then id look into it deeper. Some light dimming (that you only noticed, because you had them on, and probably parked at idle, where the alt wont make much power/amps) isnt the end of the world. 

[Kyblack76]

EDIT- sounds like you watch Big D and his amp dynos. I do to. Hes a stud. Great dude.  In his videos, he will usually do a music test with the amm1 meter at the end.

 

   Watch the impedance or load change with the freq of the music, and the power at those loads, and why you dont see a board make 5k, when he just dyno'd it showing 5k (or whatever number and board).

 

  Music is dynamic, and changes the load. When he does the dyno, it doesnt change. The load is constant. 

 

Your alternator, is also rated to make its power at a certain RPM.  Sitting idle, (low rpm) its making its LEAST amount.  Reved up, usually around 2k, is "max" output.  I know Singer, and DC Power, Mechman, all of them. JS makes a great alternator also. But there is variables boss. Everywhere. 

Shit ton of variables mate.

Happy pounding bro. 

[Joe X]

On 3/4/2025 at 2:51 PM, jgi420 said:

Yeah I got a big ass OFC 1/0g power wire going to the back to a distribution block and then I got a 4 gauge ofc piece of silver tinned going to the amp from the distribution block. 

 

And the alternator is either 240 or 2 50 amp from JS alternators. It's an aftermarket So I've already got an updated alternator. It's not stock. I haven't had stock in about 3 years and I just replaced The main starting battery 3 months ago I went from a Napa legend to an EverStart Max. 

 

I would do a couple of things:

 

1) install a voltage gauge connected to the power terminals of your amp, preferably a fast one like the one SMD sells but a cheap one will suffice and then take note of your minimum and maximum voltages while playing at high level and then post those result on here.

2) I am really serious about the advise I posted before, setup your subsonic filter to 30Hz on your skar amp, that will prevent low inaudible frequencies to be amplified, that results in reduced current draw and potentially cleaner sounding bass.

 

Then I don't know that battery but the correct battery to use should be a deep cycle one not a regular battery.

 

Let us know your voltage results, in any case if your minimum voltage is no less than 12.5 volts you are not damaging your electrical, even if the headlight dim and then you only have to find a fix for the headlighs. If your minimum voltage goes down to 10V or so then likely that battery will have a reduced lifespan.