fog light and main beam

Thread Starter

Jeffyjd87

Joined Jun 2, 2022
3
Hi all, new here but would like some advice as I'm struggling to get my head around it.

I am planning on wiring my car fog lights to activate with the main beams. I know it is possible with a 4 pole relay or even a diode to prevent back feed to the main when I have the fogs on. My worry though is that doing it that way, if I forget when I have the fog lights on and decide to flash my mains, or even turn them on, I could potentially send double voltage to the fog lights. Can anyone think of a simple way around this?

Thanks and hello

Jeff
 

shortbus

Joined Sep 30, 2009
10,044
Not sure I understand what you want. By "main beams" do you mean what they call "high beams"? If so that's usually not a good idea, fog lights usually only work with the low beams. With the high beams on you won't get much extra light from the fog lights, because of all the reflection/dispersion of light from the highs.

Most modern cars the fogs only come on when the low beams are powered, they don't light without the low beams.
 

Audioguru again

Joined Oct 21, 2019
6,616
Lots of people drive around all the time with the high beams blinding other people because they do not know how to turn off the high beams. Smart cars and smart people turn off the high beams automatically.
Some stupid cars (Chrysler and Jeep) use the high beams as daytime running lights that blind most other people.
 

Ian0

Joined Aug 7, 2020
9,521
Hi all, new here but would like some advice as I'm struggling to get my head around it.

I am planning on wiring my car fog lights to activate with the main beams. I know it is possible with a 4 pole relay or even a diode to prevent back feed to the main when I have the fogs on. My worry though is that doing it that way, if I forget when I have the fog lights on and decide to flash my mains, or even turn them on, I could potentially send double voltage to the fog lights. Can anyone think of a simple way around this?

Thanks and hello

Jeff
Don't do that, the main beams just light up the fog, and you can't see anything, so you don't get any benefit from the fog lights.
Fog lights are best if used on their own (with sidelights) or along with dipped beams.
 

Thread Starter

Jeffyjd87

Joined Jun 2, 2022
3
Don't do that, the main beams just light up the fog, and you can't see anything, so you don't get any benefit from the fog lights.
Fog lights are best if used on their own (with sidelights) or along with dipped beams.
The fogs will still work independently as they should and not back feed to the main beams. Its just extra light when I use my main beams or flash someone. It's surprising how much extra light the fogs can add to my main beams. Like on modern lorries
 

Ian0

Joined Aug 7, 2020
9,521
The fogs will still work independently as they should and not back feed to the main beams. Its just extra light when I use my main beams or flash someone. It's surprising how much extra light the fogs can add to my main beams. Like on modern lorries
And an extra quarter of a horsepower to drive the alternator! At £1.80/litre!
 

MisterBill2

Joined Jan 23, 2018
17,855
I see fools driving with their fog lights on all the time, with the belief that somehow "it makes it safer". The fools do not understand that the fog lights reflecting off of some road surfaces sends glare into the eyes of oncoming traffic, and certainly does not increase safety one bit.
The problem is that the fog lights are easy to switch on accidentally, and some drivers have no clue as to switching them back off.
Nobody has been able to provide any reasonable description of how that extra glare makes anything safer, if there is no fog.
 

Audioguru again

Joined Oct 21, 2019
6,616
Fog lights were used a ling time ago when roads had only one lane.
In foggy daylight another car can see the car with fog lights coming.
In foggy darkness the driver of the car with fog lights sees only the fog.
 

MisterBill2

Joined Jan 23, 2018
17,855
Fog lights were used a ling time ago when roads had only one lane.
In foggy daylight another car can see the car with fog lights coming.
In foggy darkness the driver of the car with fog lights sees only the fog.
The key word here is FOG !!! When there is NO FOG AT ALL fog lights are a poor choice.
In my area we have a few minutes of fog every few years, maybe.
 
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