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Reliable Source for Low Beam Bulbs?

1K views 17 replies 10 participants last post by  exbenz 
#1 ·
It looks like I have lost a low beam bulb. Research suggests the Phillips 85122. I think the 4300K color should do fine, I don't want blue. Having trouble identifying a source for genuine Phillips bulbs at a decent price. Seems to be lots of knock offs and I don't want to risk crappy output. Searches come up with a lot of five year old links that don't work. Anyone have recommendations for a source used recently where I can get genuine parts for reasonable price and shipping?
 
#3 ·
Anyone have recommendations for a source used recently where I can get genuine parts for reasonable price and shipping?
Assuming it is not the ballast, umnitza?

Regards,
Jerry
 
#5 ·
Now I'm confused. Yesterday the light was out and I was getting the check headlight message. Today didn't get the message and when I checked when I got home, the light that was out now was on but at about 50% output and different color than the "good" one. I'm still thinking bulb??? I guess I will swap bulbs side to side to confirm it is not the ballast.

The lights have to come out anyway to get new adjusters and lenses that have been sitting on the shelf for over a year. I polished them two years ago but they are really bad again. Surprised I can see the road even with normal output.

Thanks for the leads so far.
 
#7 ·
I didn't specifically note the color other than it was darker and dimmer. Yeah, I guess it had a reddish-yellow tint to it while the other one was nearly white/blue.
 
#9 ·
Thanks. Will swap just for peace of mind. This car has already dished up enough surprises. Definitely both at the same time.
 
#10 ·
I am very curious how the LCM can tell the bulb is dead other than the circuit does not consume energy. With a HID bulb you are jumping a gap so resistance measure won't work and of coarse the ballast is before the bulb? Must just be power consumption, it likely can only tell the system does not work and no more than that. Another BMW system to wonder how it works maybe it is just magic. ;)
 
#12 · (Edited)
My guess is a current sense resistor in line with each bulb or circuit. The processor measures the voltage drop across the resistor to determine the current flow and compares it to the stored value. The comparison could be done in HW rather than SW, but software is cheaper if you already have the processor and required inputs available. This is how we do it on some of our products at work (servo drives). Pretty much the cheapest way but still very good accuracy. Downside can be thermal stress on the sense resistor. That would explain why you get errors with some of the LED replacement bulbs. They draw less current so the sense circuit trips unless you add some resistance to the bulb.

Light is definitely pink. Will be ordering bulbs today from one of the suggested vendors.
 
#11 ·
I never really thought about that, good observation! It must be amperage draw since there is a high amperage draw at start up (up to 15A per ballast) then levels out around 3.8A - 4.0A once the arc is established.
 
#13 ·
I always use The Retrofit Source. I'd suggest Osram CBI's or Morimoto XB35's in 4300k. The 85122's are great bulbs, but very old technology. I had CBI's in my F150 and I have XB35's in my MB and my BMW. The new version XB bulbs have just as many lumens as the CBI's for a fraction of the cost.
 
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#14 ·
Now you tell me. :winkJust ordered 85122's from Retrofit Source. I'm sure they'll be fine and hopefully last another 17 years.
 
#15 ·
For group reference, the BMW bulb is unique from the MFR and has a specified color from BMW. An off-the-shelf Osram Sylvania DS2 bulb is not quite the same though the light output as been fine. I'm not familiar with aftermarket bulbs but I would go with the OE BMW bulb next time.
 
#18 ·
Can you post a source for this info? In all my years active on hidplanet and building xenon headlights I've never came across a statement like this. Prior to led headlights all OE xenon headlights had 4300K color temperature for maximum usable output. Some vehicles came with 85122+'S versus 85122's the plus bulbs don't color shift over time like the traditional 85122. Fact of the matter is the XB35 bulbs and CBI's are better than the OE 85122's. Lumens is the key measurement to this. The drawback to the Osram CBI bulb besides ludicrous cost is that they operate at 5500k which can be hard on your eyes at night compared to the traditional 4300k.
 
#17 ·
Take a look at a ballast circuit diagram, they are highly complex. So I'm not suprprised between that and all the complexity on an LCM PCB that failing bulbs and ballasts will trigger error messages. What sucks is that with all that sophistication, the error messages themselves are so rudimentary and non-specific. Wouldn't it nice if it said "the bulb is failing" or "ballast circuitry short". hmmm
 
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