General DRL turning off when lights on? Normal?

[Nuforce]

I have a 2014 500C with retrofitted halogen projector headlights.

I also have aftermarket LED DRL bulbs fitted.

When driving around I notice other 500s still have their DRL bulbs working when their headlights are on, so why don't mind?

Does the stock, non facelift DRL bulb have two elements?

 

[Piccolo Nero e Bella]

I have a 2014 500C with retrofitted halogen projector headlights.

I also have aftermarket LED DRL bulbs fitted.

When driving around I notice other 500s still have their DRL bulbs working when their headlights are on, so why don't mind?

Does the stock, non facelift DRL bulb have two elements?

Yes, that's correct, T20 21/5W bulbs. When the headlights are switched on the 21W DRL filaments go off and the 5W sidelight filaments switch on.

 

[steveras57]

Yes, that's correct, T20 21/5W bulbs. When the headlights are switched on the 21W DRL filaments go off and the 5W sidelight filaments switch on.

Yep your fine its something thats actually working as it should! save up your worrys and keep em in a box for later!.

 

[The Panda Nut]

If they are on less brightly its good as the others have said. If they go off all together it may indiate an issue swith the bulbs or fuses though.

 

[woz]

I have a 2014 500C with retrofitted halogen projector headlights.

I also have aftermarket LED DRL bulbs fitted.

When driving around I notice other 500s still have their DRL bulbs working when their headlights are on, so why don't mind?

Does the stock, non facelift DRL bulb have two elements?

DRL's are redundant when headlights are on is my take. I suppose if a headlight bulb fails they have some use. If others have bright DRL's on when their headlights are on, all it's doing is providing another 42W of unnecessary drag on the alternator (If they are on the bright setting?).

 

[Nuforce]

Amazon.co.uk

These led bulb specifically state they operate at dual output levels. They have a white version.

I see no reason why these wouldn't work in the same way as the dual filament T20 21/5W bulb?

Dual Brightness Modes for Versatility: These T20 7443 bulbs offer two brightness modes to suit different situations. Emitting 200 lumens during regular driving and a powerful 1500 lumens when braking, they provide enhanced visibility, signaling your intentions clearly to other drivers.

 

[Piccolo Nero e Bella]

My DRL bulb's are now twelve years old and I've never had one fail. The 21W filaments have been burning every moment of daylight driving, which in my case is probably about 97% of the 23,000mls I've covered. Those LED bulbs appear designed for a very different duty cycle, like brake lights, so I wonder how long they'd last in the DRL situation.

 

[woz]

Incandescent filament lifespan is only related to two things, time and current through the filament. As the filament ages it emits atoms and gets thinner (which is what you see on an old lamp as blackening). The reason lamps tend to fail on switch on is because the filament is already thin and the thermal shock at switch-on fractures the filament. Hopefully the filament will have been designed to give a certain number of hours (*I don't have a figure for car lamps yet but if the design parameters are similar to domestic lamps I'd expect at least 1000 hours) at a nominal typical voltage (not 12V but around 14V because the alternator will typically provide around 14.5V).
(* Bearing in mind that low voltage lamps run at much higher current than mains lamps so the filament has to be more substantial to get the same life)

So it all depends on how long it took you to do the 23,000 miles and your alternator voltage. (roughly speaking if you averaged 20mph you've had just over 1000 hours from the lamp) Even a small increase in voltage can see a filament off relatively quickly which is why lots of lamps fail if your alternator runs over-voltage for any length of time.
LED lamps are a different matter, and the life very much depends on how well the lamp is designed. The most critical parts of the design are the ability to lose heat from the led elements (aka the individual emitting diodes in the lamp (there are many) and the voltage regulation. Led's (the diodes) are designed to work at a particular voltage hence the need for some voltage regulation. There is no reason that a properly designed LED lamp (which many Chinese lamps are not) should last the life of the car. But like everything else a certain percentage of led elements will fail, and because they are (often) in series the lamp will fail. In a well designed LED lamp that is literally a matter of luck; or a matter of cheapness in other cases.
Sorry for the excessively geeky reply.

 

[Nuforce]

I ended up using these : https://amzn.eu/d/6CtzRUb

They are actually pretty white and bright.

And I added night breakers to the high beams at the same time. Took the bumper off to make it easier. Hopefully they will last a few years.

 

[Piccolo Nero e Bella]

I'd fully expect LED lamps, designed for the purpose, to last the life of the car. In 1988 I fitted a small red LED into my loungeroom Pioneer hifi as a 'power on' indicator and it's been glowing 24/7 for 37 years now! But how often have you pulled up behind a car whose LED brake lamps have dead sectors? Granted it's probably most often due to moisture ingress, or even fractured circuit boards, but I also think the diodes are being driven to within an inch of their lives to wring the maximum light output from them (particularly in the case of cheap units) and even a slight case of over-voltage, or inadequate heat-sinking, is enough to kill them.