Light Bulb Failure: Causes and Solutions

Hello!

Since I started driving my Golf, I've had the problem that I have to replace both the brake lights and the headlight bulbs more frequently than average. I've had to replace the brake lights about 8-10 times, and the headlight bulbs about 4-5 times in three years. I honestly don't know much about the car's onboard electronics , but I thought maybe the voltage from the alternator was too high.
I recently measured the on-board voltage, and it's 14.5V with the engine running. Is that too high, and could a potential overvoltage cause damage to other components (e.g., EDC, steering unit, etc.)? Why don't the other bulbs ever burn out?
What could be the cause of such a voltage surge?

Thank you in advance.
Sure, here is the translation of the text from German to English:

'Mäates' is a German word that means 'may it be.' It is often used as a wish or a blessing.

Määtes wrote:

I recently measured the on-board voltage, and it's 14.5V with the engine running. Is that too high, and could a potential overvoltage cause damage to other components (e.g., EDC, steering unit, etc.)? Why don't the other bulbs ever burn out? What could be the cause of such a voltage surge?

Hi guys.

A charging voltage of 14.5 volts is perfectly acceptable - AS LONG AS the measuring device displays the voltage within a range of +/- 0.2 volts.

However, if there is any loose connection between the alternator (LiMa) and the battery, voltage spikes from the alternator can leak into the vehicle's electrical system, which are normally absorbed by the battery.

Try looking in that direction... otherwise, I would suspect a faulty installation of the bulbs (i.e., a design flaw): aggressive vibrations are a natural enemy of light bulbs.

Then I'm relieved that the 14.5 V are within the normal range...
I've also considered the 'shock theory' related to the closing of the tailgate as a possible cause for the bulb failures. However, if that were the case, then I think it would affect the normal taillights as well, not just the brake lights .
I've only observed that using expensive 'brand-name' bulbs significantly extends the lifespan of both brake lights and the H7 bulbs for the low beam headlights. However, I've never managed to keep a bulb for a whole year, and if one bulb fails, the second one usually follows within about 2-5 days. It's just unfortunate when it happens at the front and you're driving on the highway at night...

Thanks for the tip about power surges, I'll definitely look into that.

Regards,
Sure, here's the translation:

'Hey guys' or 'Hey everyone' (informal)

Hello,

Vibrations will reliably destroy any light bulb. Is everything secure (including the bulb)?

Best regards, Rainer.

Okay, everything is confirmed. Also, these are bulbs from all four headlights. What I find particularly strange is that the second bulb consistently fails if I don't replace the broken one within a few days. I've noticed this multiple times with both the headlights and the brake lights. I've already padded the rear hatch with rubber buffers to prevent it from slamming shut, but it hasn't had any effect.

I can live with the quirk, but I'm still a little surprised by it...

Best regards,
Martin.

As far as I know, these faulty light bulbs are a problem stemming from the general cost-cutting policies within the Volkswagen Group.

Within one year, a colleague at work had a total of 13 (!!) H7 bulbs installed in his Sharan by the workshop.
He got fed up with them and bought new pears at Aldi (or somewhere else cheap), and those have been lasting for almost a year now.

Problematic are also 'highly engineered' aftermarket bulbs, such as the truly excellent Osram Silverstar.
The filament is so hard that it doesn't simply burn out; instead, it breaks cleanly. The bulb doesn't even need to glow for this to happen.

Of course, there is no warranty in such a case.

The problem isn't primarily related to vibrations, but rather to quality. And there is a sufficient lack of quality in all of these vehicles.

Stefan.

My concerns are quite similar to Stefan's. But don't worry, I certainly won't be buying any light bulbs from VW, and nowadays I can even change the H7 bulbs on the side of the highway in the dark without a flashlight...
I've tried everything from supermarket pears to expensive brand-name pears, and the expensive ones last significantly longer, but none have lasted a whole year yet .

It seems one should probably take this lightly, as long as it's only affecting the light bulbs and not causing any other kind of jolting or malfunctioning .

Regards,
Martin.

Hello,
Incandescent light bulbs also often fail if they are in a humid environment, for example, if the inside of a headlight housing is constantly fogged up. But since this applies to all of your headlights and lamps, it's probably not the cause.
Perhaps it's just the regulator voltage, which, as you know, can't be measured 'just like that.' How did you measure those 14.5 volts?
Greetings.
LANZ.

I honestly just measured the voltage at the pear-shaped connectors while the engine was idling, both at the front and the rear. All consumers were turned off, and I got approximately 14.5V. How do I properly measure the regulator voltage }?

Yes, I can rule out moisture to a certain extent, at least no more than any other car that's parked outside in the rain at night.

Regards,
Martin.

Hi,
a) What did you use to measure it? Ideally, an oscilloscope would be best, as it can detect any peaks.
b) Check the voltage while accelerating (e.g., by measuring it at the cigarette lighter). If the voltage continues to rise at higher RPMs, the regulator may have a problem with its connection.

Best regards, Rudi.

Määtes wrote:

How do I measure the regulator voltage correctly

Hi Martin,

The best way is to use a highly accurate voltmeter, connecting it directly to the alternator (on the thick wire to the ground).
Second best, at the battery.

If an assistant increases the engine speed (to >3000 rpm), the voltage should not increase by more than a maximum of 0.2 volts. Ideally, it should remain completely constant at 14.2 to 14.5 volts.

@Rudi
I used a standard digital multimeter for the measurements, but unfortunately, I don't usually have access to other types of measuring instruments.

@Ulf
I've also already checked the battery, and as you said, I had an assistant bring the engine up to about 3000 rpm. Even with short bursts of acceleration, the voltage only fluctuated within a tenth of a volt.

I think everything is probably okay here. It would also be strange if only the brake and low beam bulbs were affected by a possible voltage fluctuation. The normal taillights or even the front parking lights are probably just as susceptible to overvoltage. Unless they can handle it better due to their lower power consumption?

Regards,
Martin.

Määtes wrote:

It would also be strange if only the brake and low beam bulbs were affected by a possible voltage fluctuation. The normal taillights or even the headlights are probably just as susceptible to overvoltage. Unless they can better withstand it due to the lower power consumption???

That's what I mean. At least the H7 and H1/H4 - Super models are bred to such an extent that you have to expect increased sensitivity. I read a while ago (I think on the Osram website) that H1 Super or Silverstar bulbs are not offered in 24V because that wouldn't be tolerated in the low-frequency range.