Dim Daytime Running Lights: How & Why

Hello!

I've already read a lot about daytime running lights.
From time to time, there are hints that one...
(for Austria, for example) dimming the normal low beam headlights.
can be made to shine.

However, I haven't found anything anywhere about how bright it is.
so that the lamps can still light up.

Perhaps one of you has done something similar before.

Sigi.

Hi.

The Austrian Touring Club (OEAMTC) has compiled information on its website regarding when and how lights must/are allowed to be used.
http://www.oeamtc.at/

To adjust the brightness, as far as I know, there's a resistor wire available from VW - there's information about it in the yellow T4 forum.
http://www.t4-forum.de/

Only dimming with a resistor is stupid because you waste the remaining energy in the resistor. It's better to do it properly with PWM .

m;

For my vehicle, the original Swedish wiring uses the following resistance wire:

Code:

Widerstandsleitung: N 900 120 02 (0,27Ohm/m; kürzen auf 5480mm)

As you can probably easily see, that's 1.4796 ohms.

@dieselmartin:

Of course, energy is lost as heat due to the resistance.
However, the total power consumption is slightly lower.
And it doesn't matter whether the power loss occurs in a resistance cable,
or is 'fried' in a separate resistor.

Ultimately, the main focus is on extending the lifespan.
to increase the brightness of the lamps.

PWM would be ideal, but it's too complicated for my needs in this case.
(Then it's better to just install your own daytime running lights.)

@wolfi_b:
Are you sure you didn't make a typo?
The resistance wire is over 5 meters long?

Is this a single wire for both headlights, or a separate wire for each?

Lamp lifespan ???

I have been driving for 16 years and have had 2 H4 bulbs burn out.
Once, 3 weld seams in the dome had torn through the windshield (with a crack that was 80 to 10 cm high...).
The other time, the car was 10 cm shorter in the front.

These two damages would not have been prevented by the R-cable either.

I have never blown out an H4 or H3 bulb through normal use.

m;

No, that's definitely correct. The cable is routed along the lower edge of the frame and serves both headlights (2 x 55W).
Both headlights then have a resistance of R = U²/P -> R = 14²/110 = 1.78 ohms.
Since the resistance curve is certainly not linear, it can be assumed that the resistance is even higher at a lower voltage. Based on a rough estimate, the voltage might be around 10V.

But:

Incandescent light bulbs have a lower efficiency at lower temperatures.
Resistance, as far as I remember...

(Exception: the very old carbon fiber lamps that Edison invented).


@wolfi_b:
Could you perhaps measure the voltage when the daytime running lights are on?
what is the issue?

Then I could at least roughly estimate the power loss and the output power.
calculate the power required to light the lamps.

Hi,

@Martin: My low beam headlights (H3 or H4... whatever is in the low beam headlights that only have one filament, because there's a separate high beam headlight) failed after 45,000 and 47,000 kilometers... no external impact.

Is this actually allowed in Germany?

A PWM (Pulse Width Modulation) circuit should be much easier to build than running a 5-meter cable just to dissipate energy.

Best regards,

Jan.

Hi,

"While some power is dissipated as heat in the resistor, the overall power consumption is definitely lower than without it. The resistance value in the VW T3 is reportedly 0.2 ohms. Either that value is incorrect, or it's different from the one mentioned earlier, which is over 1 ohm."
PWM is more efficient, but it's definitely not allowed to modify the device and add something homemade. Personally, the effort required to develop something like that would be too much for me.

I would be very critical of dimming halogen lamps, as there is a cyclical process occurring within the lamps that requires a certain operating temperature. Consequences of dimming could include a shorter lifespan or blackened lamp bulbs.


Greetings,
dieter

dieter wrote:

Personally, the effort involved would be too much for me to develop something.

Sure, there are definitely more fun things to do than building torque converters suitable for automotive applications.
When I think about my mobile phone charging circuit based on the LM2675...

hollari wrote:

Could you perhaps measure the voltage when the daytime running lights are on? is at issue?

Unfortunately, it's not installed yet. The resistor wire has been lying around for months, but it's been too cold until now, and I don't have the time for it at the moment. But maybe I'll get around to it next weekend...

hollari wrote:

From time to time, there are hints that one... (for Austria, for example) dimming the normal low beam headlights. can be made to shine.

I don't think the dimmed lighting is a good solution - nowadays, some other options are also allowed.

dieselmartin wrote:

http://www.oeamtc.at/

* Standard low beam headlights.
* Fog lights only.
* Fog lights and low beam headlights (I might let myself be convinced to use them at night, but who uses them during the day?)

Hi everyone!

This weekend, I finally had the time and motivation to install the daytime running light system.
Aber wie dieter schon gemeint hat ist der Widerstand viel zu groß. Normalerweise liegen am Scheinwerfer 12,5 V bei laufendem Motor an, mit dieser Leitung (Widerstandsleitung: N 900 120 02 (0,27Ohm/m; kürzen auf 5480mm) sinds nur noch 5,1 V. Damit leuchtet das Abblendlicht so schwach wie ein Standlicht. Ich habe nochmal nachgesehen, laut AKTE habe ich die richtige Leitung und die Länge stimmt. SThat's quite strange...

dieter wrote:

I would generally view dimming halogen lamps very critically, as the lamps operate using a cyclical process that requires a specific operating temperature. Consequences of dimming could include a shorter lifespan or blackened bulbs.

Here is the translation:

This article from Osram provides interesting information on this topic. While the voltage drop is lower than with conventional gas-filled lamps, it still increases the lifespan. (at 90% of Un -> lifespan approximately 220%). Less than I had hoped for.

Basically, dimming doesn't really make much sense, but I already have the wiring in place, so I'm going to use it anyway. The only question now is how much I should dim it.
In the "Gute Fahrt" magazine from 11/2005, it states that the lamps are dimmed to 70% of their normal brightness, but I believe that 70% refers to the light output (luminous flux) instead.
The manufacturer X.Light dims its module to 80% power consumption.

As it appears, there is no guideline that the ÖAMTC adheres to.
The luminous intensity must be high enough to achieve the legally defined values.

Quote:

I'm going to try setting the power consumption to 80%.

I have a different question.

Now that it's allowed, I'd like to use my fog lights (without the main or low beam function) as daytime running lights.

Has anyone ever done this before?

Hi,

Quote:

Now that it's allowed, I'd like to use my fog lights (without the main or low beam function) as daytime running lights.

Is it certain that this is also allowed in Germany? All the links mentioned above referred to Austria...

Best regards,

Jan.

No, it is currently not allowed in Germany!

Dimming incandescent light bulbs with resistors to save energy is a double-edged sword:

1.) A resistor reduces the overall efficiency. Instead, use a step-down converter or connect the two lamps in series.

As the load decreases, the efficiency of the incandescent lamp decreases, and the color temperature shifts unfavorably.

The energy saved is not proportional to the effort involved.

But here's a crazy thought: The purpose of daytime running lights is to be seen. However, only the straight-ahead light is crucial for that. But the dipped headlight is designed in such a way that most of the light beam doesn't reach other road users, but rather the road surface.

Here's a translation of the German text:

'However, the situation is different with high beams. What if we dimmed the high beams so much that they no longer cause glare? The disadvantage here would again be the yellowish color of the light, as it would have to be dimmed significantly. However, in older cars, headlights were even intentionally a bright yellow. Due to the higher optical efficiency of the high beam headlight (where almost all of the light from the lamp is directed towards other road users), I believe there is significant potential for energy savings here.'

EDIT: As a dimmer, for example, a speed controller for model engines (PWM) could be used. From a PC power supply test, I know that an H4 bulb can still be blindingly bright at 5V. So, at approximately 1/4 of its rated power, which is 2 * 15 = 30W. The taillight and license plate light can also be turned off during the day.

Okay, now it's Ulf's turn: How much fuel is saved with a 30W daytime running light compared to a 130W daytime running light (55+55+5+5+10W)?