Headlight bulbs...

Special Coupe Frank

Special Coupe Frank

Well-known member
My '28 is developing quite an appetite for headlight bulbs...

Wiring is recent, as are the sockets and headlights themselves.

Car is still 6-volt / positive ground, running an alternator.

Ammeter shows about 10 amps charge after starting, which drops back to 1-2 amps after a few minutes running.

I've been getting the # 1188 bulbs ( 50 / 32 CP, China ) from Bratton's...

I just ordered ten of them, along with some other stuff.

I put two in on Friday night, and on the 25-mile drive home from work, one of the low beams burned-out. :(

Next night, I was driving with the high-beams on ( to have two lights working), and the hi-beam on the other side blew. :confused:

I installed two more new bulbs tonight, and on the two-block drive back to the garage, the passenger-side low beam blew again. :mad:

Has anyone else experienced high failure-rate with the chinese bulbs ? The blown-bulbs are pretty dark on the top side of the glass.

I'm going to double check voltages everywhere, just to make sure there's not an over-voltage issue.

Do the $27 halogen bulbs last any longer ?

SC Frank
 
I had similar experiences with the 50/35's. I got some old 32/32's from an auto store in town that were Mazda brand and they lasted over a year. I think the difference is that the 50/35's are made in China. The 35/35's from Brattons seem to last better. A bad ground could be part of the problem, too, so a check of all the contact points from bulb to battery would not hurt , but since you are running a regulated alternator I suspect the bulb quality is the problem.
 
Grounding is very critical on a 6 Volt system; Some people when painting the headlight bar paint the headlight mounting socket and fail to clean off the paint; this will create high resistant to ground which will often blow headlight blubs.
 
Anything that is on when the battery ground is interrupted will burn out including the dash lamp and tail light bulbs. If these bulbs are OK then the fault is probably with the bulbs. Ground problems cause the generator to run wild and produce high voltages which fry all the bulbs that were on.
 
The old ribbed Mazda bulbs had a halogen gas inside to make them last longer.

I bought cheap chinese bulbs for my Makita flashlight, they get black quick, and don't last near as long, but the box of 12 cost less than 2 real ones even with the shipping added.

For my A I use the direct fit halogen bulbs from http://www.classicandvintagebulbs.com/page2.html

I bought 1 spare bulb ---still have it unused 8 years later, I can see further than when I used the 50cp bulbs, and the charging rate can be lower on my generator than I needed with the 50cp bulbs.

I don't have a voltage regulator installed --I use the headlights to control the charging rate. ---on long daylight drives I turn on the headlights.
 
Just for kicks I would put my dash panel light on at night and see if it flares up big time with the engine running, (relative to with the engine off) indicating a short to ground in the system causing the generator to try and feed it by over-generating very high voltages.
 
I seem to recall an earlier post (old site) that traced the problem to the adjusting screw on repo sockets being to long and hitting the contacts on the back of the socket. May not be your problem, but worth a look.
 
You have to start troubleshooting this problem with a voltmeter.

Light bulbs rapidly fail when the voltage even slightly higher then the operating voltage.

What is the voltage at the battery and at the headlight bulbs while at RPM?
Is there a difference at the battery terminals or the battery connectors?
Is there a difference when the ground is on the frame vs. the battery?
 
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