I mean a 50% duty cycle is %50 on and 50% off, at a certain frequency, not sure what that frequency is, it's a very efficient way to dim incandescent lighting, but for LEDs they just turn on and off, but I agree when I had drls that were LEDs with a built in resistor...the flickering wasn't bad....but annoying enough for me to pay way too much...To be clear, there is a control board, this flicker is different than just straight, uncontrolled voltage underpowering the LED, so the flicker's not as bad as that. These are hella cheap tho
New DRL compatible headlight bulbs (1 Viewer)
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My guess is "no," I too have noticed a slight flicker if I'm not looking right at them. This is a byproduct I think of the lower wattage/voltage getting fed to the LEDs, and them stepping down in brightness. I'm not an electrical engineer, but I wanted to be sure it's not a problem before posting up in the other thread recommending them, so I've been driving around with them for months and haven't blown a fuse or anything else; I can't think of why it would hurt the alternator or any other electrical component. In other words, the flicker isn't a capacitor sending surges back into the system or something, my money is literally on it's fine, and for the $ "good enough."
My amateur BS science armchair degree says that LEDs don't actually dim; they just change the rate at which they turn on and off.
I THINK all LEDs actually switch on and off super fast, which is why a camera can see it (causing the roll effect when you point a digital camera at some LED bulbs). So my theory is when these are receiving DRL voltage, the control board says dim to, say, 50% output, which slows the on and off rate to less than 50 on off cycles a second, or REALLY close to that, so you can kind of see it. However, it is in fact dimmer.
When you click on high beams, the rate of on and off goes above 50Hz, so you no longer see flickering, and the brightness goes way up because the LED is on for longer, like say 100 on off cycles a second. So a manufacturer has to pick an LED that, when putting out low brightness, can be low enough but at more than 50 on/off cycles a second, and still offer a really bright output at full voltage.
I dunno. It makes sense to mehere's another way to look at it - so my guess is if you eliminated flicker entirely in low beam mode, either your low would be a little too bright and the highs a little too dim, or the lows would be OK and the highs would put out too much heat and be supernova bright. This is the challenge of making an LED bulb for this specific application, where the bulb serves as both low and high beam, the manufacturer has to pick an LED that is JUST right at low and high. At any rate, I can't see the flicker if I'm standing about 10ft plus away, will probably add that disclaimer when I decide to post up in the other aftermarket thread...
As an Electrical Enginerd, I can confirm your statements are correct regarding the effect of flicker on the vehicle. I turned off my DRLs because it may trigger epilepsy for super sensitive on coming drivers.
If you look at a dual function halogen bulb you would see 2 elements, one for DRL and one for high beams. The signal from the GX is ON or OFF and then when using LED bulbs, the driver interprets both signals (DRL and HB) and alternate the frequency on the single output to the LEDs.
Solution 1:
A dual output driver generating the same frequency to 2 separate sets of LEDs with a low voltage for DRLs and full voltage for High beams
Solution 2:
A driver that would sense which input is on and converts it to a change in voltage while maintaining the same Hz rate. This would require special LEDs that has a wide operating voltage range.
Another important factor is the effect of either solutions on the longevity of the LED life cycle.
I should add, if you don't get the way too expensive xenon depot LEDs...you pretty much have your high beams on all the time...but at a flicker during the day...I think a lot of people just turn off their drls and use the LEDs for high beams..or just get a steel bumper that has led drls
