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  #11  
Old 08-18-2013, 06:47 PM
jdd jdd is offline
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Quote:
Originally Posted by brian1950 View Post
It is a well known fact that LEDs will not tolerate flickering. I have had several sets burn out or go brown in the centre and weaken in brightness after only a few months, so I do know what I am talking about.
I would respectfully suggest you do more research regarding LED bulbs. They do not tolerate cold monitoring, or as you refer to it as lamp check signal.
As an electronic engineer with over 30 years design experience I have used many different types of LEDís in various applications and this is one of the most absurd things I have ever heard of.
There are many reasons why LEDís die but I can assure you pulsing them within their specs is not one of them.

If I get time later today Iím going to have a look at this lamp check signal on my own vehicle with a CRO to see if thereís anything unusual with it.
If itís a simple 0-12V switched signal, then there is no possible way this would cause premature failures.
If the signal switches from positive to negative there is a possibility this may cause issues if the lamp unit is not designed correctly as it would be momentarily applying reverse polarity voltage to the LEDís which they donít like. If this is the case, the cause is a design issue with the lamp unit and not the fact that the LEDís are being pulsed.

As an example of pulsed LEDís in an automotive environment; have a look at the brake/tail lights of any high end Audi or VW with LED lights. You will notice there is a bunch of LEDís that are used for both the tail and brake lights. These are pulsed very quickly to reduce their brightness when the tail lights are on without the brake lights, the pulsing stops when the brake lights are on to provide the added brightness for the brake lights. You will probably also find this setup on other Euro cars and from memory the later version of the Prius is setup like this too.
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  #12  
Old 08-18-2013, 10:15 PM
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I'm sorry but you are going off on a tangent and are completely on the wrong subject. I am not going to continue this debate with you as you are obviously convinced you know everything, and i am not willing to continue accepting your rudeness. I do not make absurd statements. You apparently know nothing about BMWs, or cold monitoring of LED Angel lights. End of story!!
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  #13  
Old 08-18-2013, 10:31 PM
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Cold monitoring off for Angel Eyes - KALTUEBERWACHUNG_SL_LV-nicht-activ; KALTUEBERWACHUNG_SL_RV-nicht-activ

Angel eyes still work when turned on but no longer flicker when engine first started.

Unfortunately I do not have the equipment to do this myself, so I Try to remember to turn mine on before starting engine to prevent cold monitoring from occurring

Thanks Frozenwaffles for your replies.
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Last edited by brian1950; 08-18-2013 at 10:34 PM. Reason: Thank Frozenwaffles
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  #14  
Old 08-19-2013, 03:43 AM
jdd jdd is offline
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I have checked both the cold and hot monitoring lamp check signals on my own X5, with some interesting results.
For the benefit of those non-believers on this forum I performed this test on the angle eyes circuit, although the results are likely to be the same for a number of other light circuits.

During hot monitoring the bulbs are pulsed once every 80mSec with a clean Ďsquare waveí from 12V to zero and back to 12V, this pulse is about 5mSec in duration. The hot monitoring phase starts more or less straight after the cold monitoring phase and is done so that if a bulb fails while youíre out driving around it will bring up a warning on the dash.

During the cold monitoring phase I found both positive and negative pulses.
While the positive going pulses should not cause any issues, the negative going ones are large enough to potentially damage a LED.
As I have mentioned previously, the issue is NOT the fact that the LEDís are pulsed, it is the fact that during the cold monitoring lamp check there are negative pulses generated which LEDís are sensitive to.

A simple solution for those who donít have the ability to turn this off would be to splice a diode of suitable amperage (eg IN5401 or similar) in series with the angle eye circuit with the grey wire connected to the anode and the cathode connected to the positive side of the LED.

Last edited by jdd; 08-19-2013 at 03:44 AM. Reason: removed references to forum troll
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