DiamondNoir2K5

Hi Guys,

Looking for someone with more electrical knowledge than me to explain something.

My '05 C230 Sedan is 5 months old. No problems whatsoever. A couple of weeks ago, I installed clear sidemarker lenses. They came with two amber 194 bulbs to replace the clear stock ones. No problems with that. Amber bulbs were nice and bright. Loved my new clear sidemarkers.

A week or so ago I got a pair of Stealth Auto 194 bulbs to improve the look. After less than a week of light driving, I noticed the left side bulb get dimmer. Yesterday, it burned out. While replacing it I noticed the right side bulb was pretty dim too. A few hours later, it burned out too.

I put the amber bulbs back in, and they work fine, nice and bright, but obviously I would prefer to have silver-stealthed bulbs in there.

Any ideas what the problem is here? My bulb dude is sending me free replacements, but I wonder if they will do the same thing too. Pardon my ignorance, but what kind of electrical phenomenon or defect would cause a bulb to slowly get dimmer and then burn out? I'm pretty sure it is not my car's electrical system, since the amber and clear bulbs work just fine, and have for 5 months.

I'm trying to figure out if these Stealth Auto bulbs just sh*t, and I should just try to find another brand altogether.

TIA.

amdeutsch

It appears you have a manufacturing defect in those bulbs. This could be for a variety of reason: cheaper materials, less than adequate assembly procedures, etc.

DiamondNoir2K5

Hmm, that would suck. It's weird how they both burned out within a day of each other. A 194 bulb is not a very complicated thing, it's hard to imagine they could be manfactured so poorly. Stealth Auto seems to be a pretty popular brand.

These bulbs are silver-coated. Could that have anything to do with it? Seems like I'm not the only one in this forum who has used clear sidemarkers+silvercoated bulbs, and no one seems to have had this problem before. I did a search.

Maybe my two bulbs are just from a bad manufacturing batch?

DiamondNoir2K5

So I was replacing the second the of the burned out Stealth bulbs this morning, and as I was pulling it out of the sidemarker socket, the damn thing crumbled in my hands (thank god I was wearing gloves)!!!!!

I had to pick out the fragmented base of the bulb using tweezers.

What the hell makes a glass bulb do that?

I know it's winter, but here in NorCal that only means 50 degrees F!!!!

Capt Nemo o2

Here is a possible theory...

The silver coating on the lens makes the lens reflective, alowing some of the light waves to reflect back into the bulb. This could increase the temperature of the bulb. The bulb itself, being in a small, unventillated area, is already subject to higher than normal temps. This in combination with the reflected light waves increases the temperature of the filament. Increasing the filaments temperature increases the electrical resistance across the filament (as temp of a electrical component rises, its resistance rises). Due to the increased resistance the bulb now glows dimmer. This process repeatedly brings the bulb close to burning out and then back down, eventually the filament weakens, in which case it doesnt take much for it to break.

Its just a theory, and I'm probably wrong, its most likely a bad batch of bulbs!

PS: I'm in the middle of studying for my Circuit Analysis final when I read this! I just wanted to feel like I learned something I will actually use!

rubenl

I've had no issues with mine....

DiamondNoir2K5

Capn Nemo. Thanks for the analysis. I'm hoping it's just a bad batch. I can't imagine they're all low enough quality to burn out in a week. Good luck on your final!

And reubenl is living proof, I guess. I just hope the replacement bulbs I get are from a different batch!

Capt Nemo o2

[QUOTE=DiamondNoir2K5]Good luck on your final!QUOTE]

Thanks, and lets hope the next set works right!

FrankW

the problem is definitely w/ the quality of the bulb. what brand is the bulb?

DiamondNoir2K5

Frank,

That's not clear from my post? It's Stealth Auto brand.

You're not going to tell me to black out my side markers, are you?

FrankW

the brand must be the problem. Get some Silvanias or PIAA if they make'em or just use the amber bulb.

Outland

Most of the ricer-esque **** is just that, ****. Nemo had the right logic. Same reason you don't touch the glass on the high beam bulbs and create hot spot.

Get yourself a set of LED 194 replacements. They'll look cleaner, and won't burn out. I have LED's for my turns and city lights. I have the clear corners too(just like yours), but I'm happy with the amber bulbs for now.

DiamondNoir2K5

The major brands don't make silver-coated 194 bulbs. Silvania has diadem coated bulbs, which I use for my front and rear (1157 and PY21W) turn flashers, but they don't make diadem 194 bulbs.

DiamondNoir2K5

Well, at 55W the H7 bulbs burn a hell of a lot hotter than tiny little 5W 194 bulbs. I doubt a hot spot was the problem.

Well if I was just going to use the amber bulbs I wouldn't have posted this thread in the first place.

What do you use to load balance your LED's? Inline resistors?

Outland

Well obviously if you used the amber bulbs you wouldn't have posted this. I just said I'm happy with them for now. I'll probably add more LED's there at some point.

I scotch locked a second socket on the line, and just pluged the OEM bulbs into it, then let it hide out of site. Works great, and a lot cheaper than the load equalizers.