Relaying Headlamps

[James467]

Yes, I know this has been discussed before.

I'm relaying my headlamps and looking at the current standard two relay setup main and dipped will be on at the same time when main is selected.

To me that seems like a lot of power (60+55W so 115W) and heat for a standard H4 bulb to take. I'm concerned that my plastic headlamp bowl will melt during long duration's of high beam being used, which I expect it will be during the RBRR next year and drives on the continent.

Looking at the internet a lot of cars dipped beams extinguish when main is being used, apart form when you flash dipped and mains.

Thoughts please.

[dursley92]

Bit surprised as I all the cars I have had the dip filament usually goes out on main beam with a standard H4 setup?

[James467]

The way I see it all that is needed is an additional relay that the low beams run through triggered by high beam, when high beam turns on it turns off the low beam through terminal 87a.

If you wanted all lights flash function then you could set up a time delay relay for say half a second?

[Galileo]

Use a normally open and a change over relay.



Normally open relay to energise headlight circuit, then after that a change over relay with dipped on 87 and full beam on 87a, wire full beam switch to 85, 86 to chassis.

[James467]

Perfect, Thanks!

[Carledo]

Yes, I know this has been discussed before.

I'm relaying my headlamps and looking at the current standard two relay setup main and dipped will be on at the same time when main is selected.

To me that seems like a lot of power (60+55W so 115W) and heat for a standard H4 bulb to take. I'm concerned that my plastic headlamp bowl will melt during long duration's of high beam being used, which I expect it will be during the RBRR next year and drives on the continent.

Looking at the internet a lot of cars dipped beams extinguish when main is being used, apart form when you flash dipped and mains.

Thoughts please.

Why would you have dip and main on at the same time? If you have 2 relays, 1 for dip and one for main and use the dipswitch outputs as switching wires to the relays (This is kindergarten stuff, I know) then when you select main beam, the main beam filament of the outer bulb is energized and the dip filament drops out as the dip lead out of the dipswitch is no longer live so no switching feed to relay. Sure you CAN get both on at once, if you have the headlamps on dip and pull the "flash" switch - but that is only momentary and no big deal! At least, it's ok if you have relays and aren't melting the dipswitch!

For electrical purposes you can treat a twin filament bulb as 2 separate lamps.

Steve

[James467]

So the column stalk turns off power to the dipped beams when you flick it forward then, thus de-energising the relay.

<slaps forehead!> It's all so simple now!

Ok, now I'm feeling a bit silly!

Thanks Steve for pointing out the blinding obvious to me!

[Robert 352]

Details of my headlamp relay setup can be seen on my restoration thread where I mounted 3 relays on a plate that is tucked in beside the radiator. Some were concerned that the relays themselves might be exposed to rain/moisture passing beside the radiator itself but I positioned them so that they were shielded from the wet but in a position where they would be in a relatively cool position. Each relay is fused and is wired so that the relay pack plugs back into the standard wiring harness. The 12 volt positive feed was taken from the main battery to starter motor plug arrangement so the wiring looks as if it is part of the BL wiring loom.

Originally I used only two relays but added the third so that the low beam remained on when the high beam was triggered.

It all works very satisfactorily for me.

Robert

[Galileo]

So the column stalk turns off power to the dipped beams when you flick it forward then, thus de-energising the relay.

<slaps forehead!> It's all so simple now!

Ok, now I'm feeling a bit silly!

Thanks Steve for pointing out the blinding obvious to me!

To be fair, I never gave your question a second thought either! And I should know better as I'm always telling people at work not to just solve the problem given, but find out what the problem actually is...

[Carledo]

In need of a "smug" smiley here!

But probably a good job there isn't one, there, but for the grace of God, go I!

Steve

[killysprint]

Have a word with Jeroen - he made and supplied me(as well as a few others) a new front loom which includes relays for the lights (x2), the horn and a one for the electric fan.

Relay block sits under the battery, loom looks stock.

Quality piece of kit.

[tony g]

The only time all filaments are lit is when "flashing" by pulling the stalk towards you.

Tony