High consumption of headlight bulbs - poor quality?
 

Greetings!

With the carburetor sorted out, I'd like to move on to other issues. Ever since I bought my Amazon nearly two years ago, I have had a high consumption of headlight bulbs. Only headlight bulbs. The other bulbs in the car haven't been touched or replaced so far.

One of the first things I did when I got the car was to clean up all the grounding points and made sure every electrical connection in the engine bay was clean. I have read people complained about dim lights, slow starter speed and such with 6 volt electrical systems. That's why I sorted out the electrical connections early on, to make sure they were good. Preventative maintenance.

A couple of weeks ago, a bulb I replaced two days prior, burned out. They only last a few days or weeks at a time. Almost every time they turn white/blue cloudy inside. Sometimes the rods for the filaments bend and break the connection. Or a combination of both. The white cloudy surface is the most common one. They always go out when turning on the lights at idle. Never both at the same time, but it appears to be random which side it is.

I rechecked the electrical connections and have a good ground, and good electrical contact in general. For good measure I cleaned them again. The bulb plug is nice and tight and in no danger of falling out on its own. The charging system outputs a stable 7,5 volts when the engine speed is high enough.

At this point I don't know what could be wrong. I'm convinced the brand (Bosma) must be of exceptionally poor quality. After a lot of searching, I found another brand called Amolux, but it doesn't instil a lot of confidence either. The packaging claims it to be a halogen bulb, and the key is offset, making the filament sit at an angle. Regardless, I will try these when the headlights burn out again.

Anyone else that has experience with these bulbs, or got any other suggestions?

7.5 volts is 25% above a nominal 6 volts. That is pushing the limits and is equivalent to running a 12 volt system at 15 volts. Is that the voltage with the headlights switched on? If it is then I expect that the voltage may be a little higher when the headlights are off which means that initial current flow (before the bulb heats up and current drops) may be really high and the thermal shock on start up may be killing the bulbs.

I can't comment on 'why only the headlights'. However, I would be inclined to see if the regulator can be adjusted to around 7 volts with the headlights on. Incandescent bulb life is a very non linear function of operating voltage and deteriorates quickly with increasing voltage.

Also, given that the market for 6 volt automotive bulbs must be incredibly small, I expect that the bulbs are likely originating from some low production cost country so quality and spec may not be what it used to be.

The bulbs burn out at idle, in other words essentially battery voltage. It doesn't have a modern alternator fitted, so the engine speed needs to be higher for it to start charging. When they work, they work. Never had a bulb failing while driving, only when pulling out the light switch to turn on the lights.

Admittedly, the light switch isn't original. The original one was more of a rectangular shape with screw terminals. It had failed, so I replaced it with a later style cylindrical switch with spade connectors. I drilled out the rivets to disassemble it and gave the switch a good cleaning and lubrication before installing it.

I recall reading somewhere that 7,5 volt is acceptable, but could read through the shop manuals again tomorrow to make sure. It needs to be higher than 6 volts anyway for the battery to charge. Considering 14,5 volts is common charge voltage on 12 volt cars, I didn't find it to be high enough to be of any concern.

Sam;

A cloudy internal glass surface occurs when air within the glass envelope allows the filament to burn, and air within the envelope is a result of a failed seal...so I would agree and call that a manufacturing error/poor quality, and also call the failure unrelated to system voltage.

Good further info from 142guy...I do agree, those voltages are typical, although I don't like to see much more than a 15V system V...

Cheers

BOSMA, taking Bosch and Osram , to confuse the buyer. My last V70 ate a pack of 10 , Pound Shop H7
bulbs in less than a year. Crap!

Found in a green book that the charge voltage range is 7,0 to 7,5. Although my car is at the high side, it is still within spec.

Have tried to find a reputable brand, but so far I have been unsuccesful. Some have said I should replace the lamps to H4, but 6 volt halogen bulbs are still very unconventional. The conversion is probably illegal as well.

Attatched a couple of pictures of a bulb that failed without leaving a cloud. In this case, the internals bent enough to break off the filament wire where it was welded.

have you checked the voltage at the headlight connector try to source some alternative make bulbs possibly amid at Japanese 6 volt motor cycles .

I agree that the voltage needs to be above 6 volts for the battery to charge. My only point is that 7.5 volts is pushing the upper end of acceptable and higher voltages will shorten bulb life. Even if you don't have an alternator a generator will still have a voltage regulator and that regulator will typically have an adjustable operating point.

However, given the photo that you posted and the additional information about the circumstances of failure I don't think that high voltages are the primary problem. I suspect that you may just have a bulb quality issue with the headlight bulbs and there may be no way around that if you have a limited supply of vendors. That would explain why you don't appear to have a problem with a high failure rate on the other bulbs in the car failing.

Switching to a halogen bulb might provide a solution providing that the manufacturers of these bulbs have better quality control. If you are going to switch, you need to be aware that depending on the age of your car, there may be a mounting base problem. P45 is the old style mounting flange and P43 is the more modern mounting flange. The most commonly available 6 volt halogens are P43; but, you can still find P45 if you search

https://vp-autoparts.com/en/artiklar...-55w-p45t.html

If you have a P45 reflector the P43 will not fit unless you get one of these adapters.

http://www.volvosolutions.com/Misc_P45T.html

The adapters are rather expensive. Personally I would just purchase a new 7" H4 compatible reflector to go with a P43 base halogen H4 bulb.

The only reason to switch to the P43 base H4 style halogen bulb is that it might give you some different supply options. In the long term, 6 volt H4 halogen may incur supply problems. 25 years ago my local auto supply store used to have rows of 12 volt H4 halogen bulbs to choose from. Now you have to search to find the H4 style bulbs so 6 volt P45 base H4 halogens may have a very limited number of suppliers with the same quality problems.

Looks like I have to search for different brands and try them out. Maybe find some new old stock bulbs.

Another issue with halogen bulbs is that they're technically illegal on this car. The vehicle regulations I have to follow specifically say headlights cannot be more than 45/40 watt. Most halogen bulbs are 60/55 watt.

A 12 volt conversion would provide more possibilities, but that isn't straight forward either.

It is not too hard to find H4 bulbs in 25/25W and 35/35W ratings. But, they all look like the P43 base so you need the adapter or lens conversion.
https://www.octanelighting.com/auto-.../6-volt-bulbs/

45/40W h4 in 6 volt appears to be rare / non existent.

Actually, you could do a partial voltage switch, converting just the headlight circuit to 12 volts while leaving the rest of the car at 6 volts. Just install one of these (or one of 100 similar devices) to power up the headlight circuit:

https://www.amazon.ca/DIGITEN-Conver...6515186&sr=8-5

They are a solid state boost regulator with an input form 5 - 11 volts and an output rated at 12 volts 10 amps which could power 120 W of lighting. They come in various sizes, just size to meet your wattage rating with a little extra for insurance.

That said, finding an existing supply of P45 base bulbs that do not burn out would be the easiest solution. Good luck with that!