700horses

I've searched the forums and googled around and still cannot find a clear answer...

My w211 did not come with the bi-xenon headlights, so I upgraded to a 35w 6000k HID kit... I don't like how dim they are and want to install 4300k Philips H7 HIDs


---> MY QUESTION: Is it ok to run 55w bulbs (Philips 4300k) with the already installed/mounted 35w ballasts??? Is there an optimal difference? Does it matter?





Thank you in advance if you can answer this and enlighten me on the matter.

Craftysince86

is the difference in wattage an optional choice or is that just how comes? i didn't know they came in different options but i've used different bulbs on the same ballasts so from my experience i would say you are ok

and the 4.3k puts out more light in our visual spectrum, it's actually the optimal temp, so for brightness that is going to be your best choice.

700horses

Thanks for chiming in, I guess my concern comes down to brightness.

Will the 35w ballast be strong enough to power the 55w bulb to full bright temperature?

Or would the bulb be brighter if it was a 35w bulb to match the 35w ballast?

I read a few places that it would be ok, but will matching the bulb (35w) capacity to a 35w ballast be more optimal? (than 55w bulb in 35w ballast).

Anyone got a for sure answer on this?

700horses

Anyone??

I guess this is another question that cannot be answered??

This isn't the first time I've stumped MBWord!!!

kurtismayfield

Yes it does matter.

Its kinda weird, so i will break it down and explain whats going on and why the 55 watt will not be brighter than the 35 watt for very long...

The ballast regulates the total amount of current (current = amps) that flows to the bulb and the time it takes to reach the rated output. The output voltage of the ballast and the length of the arc effect the brightness of the light that the bulb produces. So how long is the arc?

In a brand new bulb, the arc is short, and the bulb is very bright, but over time, the electrodes on each end of the bulb erode, increasing the distance between the electrodes. Hence, the arc gets longer and light output decreases.

To recap ***As the arc gets longer, the light output diminishes.***:
As the arc gets longer, the voltage needed to maintain the arc increases. Every ballast has a maximum voltage output capability for operating the bulbs based on it's rated capacity i.e. 35 watts, 55 watts etc.. Eventually the voltage required to maintain the arc reaches the maximum voltage of what the ballast was designed for and it will then struggle to keep the bulb lit, or fail to ignite it altogether. (This will begin immediately for you as the voltage to ignite and maintain the 55 watt bulb wil be near the max output of the mismatched ballast..)

Now we will compare the two bulbs powered by the appropriately rated ballast for each bulb:
A 35 watt bulb may see a service life of 3500-5000 hours with the 35 watt ballast while a 55 watt bulb may only see a service life of 1000 hours with a 55 watt ballast. if you use 55 watt bulbs with the 35 watt ballasts, you will need to change them prematurely (after much less than 1000 hours use because of the ballast power rating and the light bulb power rating mismatch).

Eventually the 35 watt kit ballast will fail and may or may not take out the bulbs and the fuses with it. It may also damage the wiring harnass.

The bulb warranty and the ballast warranty will both be voided because they were not used as designed.

Light Brightness:
Because of the power mismatch, the electrodes in the 55 watt bulb are eroding at a exponentially faster rate and consequently the light output is diminishing as the length of the arc is increasing.

A 55watt bulb should be about 20% brighter than a 35 watt bulb when using the properly rated ballast for each bulb. After 100-200 hundred hours of burn time with a mismatched ballast, they will be the same brightness level, but the 55 watt bulb will be toast in short order. The 35 watt kit will continue to put out the same level of brightness (as the 55 watt bulb was shortly before it failed) and continue to function for another 3000-4500 hours of burn time.

So in the end you end up with essentially the same brightness output as the 35 watt bulb but you really pay much more for it!


props to sandynlily

700horses

WOW! THANK YOU!! That is exactly the type of explanation I was looking for, truly educational.

Any recommendation on a bright, reliable bulb? (4300k or 5000k) and/or a reputable place to buy a pair?

Thanks again!

700horses

I've read Philips are good (but haven't been able to find 4300k in 35w)

Also, I read that in mid 2011 the w212 upgraded their OEM bulbs to Osram 5000k... Perhaps a pair of these will be sufficient?

Any thoughts, advice?

dixoeileen

I guess my concern comes down to brightness.

kurtismayfield

One issue I forgot to include in my post...

In order to be truly legal you would need to take the following steps.

1: If your vehicle does not already have an HID compliant headlight housing, you will need to upgrade or change the housing over to an HID compliant housing. In other words, if your vehicle did not originally come with xenon lights, you need to change housings.

Alternatively, you can call and request HID bulbs that come with a reflector shield for use in reflector housings - this will give you a decent cut off line and reduce glare to oncoming traffic. These reflector kits are built according to OEM specs for use by high end vehicle manufacturers. Reflector shields are what you see on a set of D2R bulbs which are designed to be used in OEM HID compliant reflector housings. When using an aftermarket kit in reflector housings that utilizes the D2R style reflector shield, you will ensure proper reflection of light output while minimizing glare commonly associated with aftermarket kits.

2: Install a converion kit in your vehicle that uses HID bulbs in the "White" to "Baby Blue" light spectrum such as 4300K - 6000K.

My lights are OEM and I encourage you to do the installation correctly. Have you noticed that some HIDs are blinding and others are not? Thats the difference between legally installed and otherwise. And, the cops need only to be blinded by you with the incorrectly installed bulbs to begin salivating about a headlight ticket! Your radar detector won't save you here!

700horses

Yes, my car already has projector housing headlights and I already have an HID kit installed (6000k), but it is a bit dim in the rain and fog for my taste, hence this post.

So what brand of 35w HID 4300k or 5000k bulbs are the brightest?

I've heard Osram or Philips... Anyone have any actual model numbers and reputable place to purchase them??