Headlight Bulb Durability

[FarrisK]

I realize it has probably been asked before, and I just can't find it, but is there a way to make our headlight bulbs last longer? I'm going to be replacing mine this weekend for the 3rd time in 18 months... My mom's Mercedes hasn't needed a bulb changed in 4 years!

I was thinking that running a higher wattage bulb would work, but I think all that would do is make it brighter and get me a ticket. Perhaps if I were to wire in a resistor to reduce some of the current going to the bulb?

By my calculations, each headlight draws roughly 4.6 amps. (P=IV) If I want to reduce that, say, 20%, I would be drawing ~3.7 amps, which would give me 44.4 Watts of light.

I think a one ohm resistor that can handle some SERIOUS wattage would give me the drop in current that I need. Are there any Electrical Engineers out there that can confirm or deny?

[FarrisK]

Originally Posted by FarrisK

I think a one ohm resistor that can handle some SERIOUS wattage would give me the drop in current that I need. Are there any Electrical Engineers out there that can confirm or deny?

Here's my reasoning:

Right now, the bulbs draw 4.6A. Because R = V / A, and substituting 12 volts for V and 4.6 for A, I get 2.6 ohms for the headlights.

If I want the bulbs to draw 3.7A, R = 12V / 3.7A = 3.25 ohms.

So my delta-R would be about .75 ohms... which I rounded up on in my first post.

[noR]

If you've got that level of electical knowledge. Why not add a capacitor or regulator or something so they stop getting brown-outs till they die.

[FarrisK]

Originally Posted by noR

If you've got that level of electical knowledge. Why not add a capacitor or regulator or something so they stop getting brown-outs till they die.

You mean to drop the voltage down a bit? Thats kinda what I was thinking...

[LadybugEwa]

Your calculation makes sense to me, please let me know how you get on in practice.
They make these 'voltage regulators' for cars. I've often wondered if installing one of those would solve this lightbulb problem, but those kits are like $100.
I also have a suspicion that the wire used for the headlights to draw power is too thin (because of the periodic dimming issues).

The longest I've had a headlight lightbulb last was about 16-18 months, but it was an exception to the rule. This was a pair of silverstars, swapped in at the same time (and correctly). The first one went after 8 months. I got and swore off silverstars and replaced that one with a regular GE H1 bulb. The SECOND silverstar's lasted until now. I wonder if it's something to do with their different resistance.

[Lnzbug]

I too went thru a bunch of bulbs. It seemed like it was needing a new one every two months. I then bought a bunch at a great price from an orger and would you believe I haven't needed one in a few years Go figure

[fohveh]

Install an HID aftermarket kit 6500k and be done with your bulb issues. It can't be the wires going to the bulbs because the whole car dims periodically, not just the headlights. The whole gauge and all lights associated with any component all at once. The dimming is related to a load place on teh alternater or something else since it sucks energy at regular intervals. I did a HID conversion two and a half years ago and have never had any further issues, the lights appear new each and every time I turn them on. Since the bulbs current is regulated in the ballast there is no dimming effect when the rest of the car dims. So regulation of current is definantly and issue here.

[jazzcat]

i think there is something else going on with the lights..my drivers light bulb has been through 4 sets of headlights and hasn't had any issues..only reason my passenger side has been replaced was because i dropped the entire bucket and the bulb broke

changing resistance would be a good fix but you are just hiding the actual problem at that point...just my .02

[Smileybug]

I had one of my bulbs die about a week after I got my car. Took it to the dealer to get it replaced and after over 3 years no burned out bulbs. *knock on wood*

[noR]

Originally Posted by FarrisK

You mean to drop the voltage down a bit? Thats kinda what I was thinking...

I actually meant more like something to hold a charge so that when power dips, there's something to take up the slack so the bulb doesn't feel the change in current.

[FarrisK]

Originally Posted by noR

I actually meant more like something to hold a charge so that when power dips, there's something to take up the slack so the bulb doesn't feel the change in current.

I'm less worried about power dips as running too much current through the bulb. I think that's why they burn out so quickly.

I found some nice 10 Watt, 1 ohm resistors on digikey... I'll order some this payday and see what happens.

Also, HIDs are out of the question for me. I don't feel like blinding other drivers, or going through all the extra work.

[lkchris]

Here's a good approach to improve headlight bulb longevity:
Disabling Daily Runing Lights (DRL's) - How-To

[noR]

I don't believe disabling a passive safety feature is really a fix either. But yeah, guess that'd work too.

Don't they get 35W in daytime mode, and 55W when they're 'on'?

[miffmole]

Does anyone know,
a) The life expectancy of stocks HIDs, and
b) How expensive are they to replace?

Thank you.

[Lmhansen]

Disabling DRL doesn't affect light bulb longevity. If that was so, then most people would have replaced their bulbs 3 times in 18 months, just like FarrisK, and that's just not the case. I replaced my bulbs 18 months ago, and they are still doing fine. My other car is 6 years old, has DRLs, and I've replaced the bulbs three times in that time.

[FarrisK]

Originally Posted by noR

I don't believe disabling a passive safety feature is really a fix either. But yeah, guess that'd work too.

Don't they get 35W in daytime mode, and 55W when they're 'on'?

I don't think they are quite that low in DRL mode...

...but it doesn't matter. I drive with my headlights "actively on" whenever I drive. It's just a habit I've gotten into since I got my license, so that don't forget to turn them on at night.

I will update this thread when I get the resistors tested and installed.

[Fowvay]

7+ years of ownership and in that time I've been forced to replace 4 bulbs. 1 Fog, 2 low and 1 highbeam. Now last summer I noticed a distinct color difference between the bulbs so I bought 6 sylvanias (the cheap ones)and matched them. I do a LOT of night driving and always burn my fogs with my lows. So if anyone should have issues it should be me.