I am trying to find some small 32 volt bulbs for a Star 845 C marker light, a common marker light found on many private cars. These bulbs seem hard to find, and I can't get a good response when I call the manufacturer of the marker light. I like to keep things old school and don't want to go with LED. I've done the usual google searches but has anyone in the RYPN Nation actually bought some of these recently? Any leads would be appreciated.

A 36vdc bulb will work fine, and is much easier to find.

http://www.bulbtown.com/36_VOLT_LIGHT_BULBS_s/398.htm

I haven't done anything with one of those for years - what style bulbs are they? IIRC they were a bayonet base and 25W?

You might try Don's Bulbs. http://www.donsbulbs.com/cgi-bin/r/t.pl

As I suspected, the Star 845C is a FRA rear-end marker light (49 CFR 221). As such, there are certain requirements as to brightness. Changing from one voltage to another will certainly impact the brightness and might impact it's ability to retain its certification. It might be worth looking at before changing voltages.

G.F.Payne
Baltimore, MD

Thanks for the responses so far. Yes, these have a bayonet base, but I haven't been able to confirm the wattage or amperage of the correct bulbs. I have checked Don's Bulbs and Bulbtown and they may have the correct ones, if I can just verify the specs. A 36V bulb of course should work just fine.

I would point out that Star's website indicates that the 845 C uses either a 12V, 36V or 72V lamp...they also have a page of replacement bulbs they can supply or direct you to a distributor. I also noted that they have a support page for their products (providing phone numbers for contacting them)...I am having to assume that with your Google search you are already aware of this...but then again maybe not since you refer to needing a 32V bulb when the manufacturer indicates/specifies the lamp to be 36V.

Doc:

Thanks for your response. Even though the Star website indicates the marker lamps they stock work on 36V bulbs, they give me a blank stare over the phone when I try to order a replacement one. I've done it twice with them and I keep getting 74 volt bulbs. The bulb page on the Start website does not show any 32/36 volt bulbs. This is why I am reaching out to RYPN forum. I have already done pretty thorough digging in all the obvious internet places. If I could confirm the wattage and amp needed I should be able get some from the several other on-line bulb sources.

Your system is 32 volts from the batteries, as most old locomotives and passenger cars were. But they charged at 34-38 volts, hence a 36 volt bulb.

A 36 volt bulb will work just fine and I would bet falls in the FRA brightness guidelines from say 30-and up volts. As Mr. Payne pointed out, regulations that require a certain brightness or distance of beam can cause issues when using out of spec bulbs/fixtures. The bulb voltage isn't your problem in this case, it is making sure you get the same wattage.

Dare I ask, there isn't a number stamped or printed in the base or on top of the bulb is there? I imagine there isn't as you would have found it hopefully. I can go look at some this weekend and see if the bulbs installed in them have a number on them. Even a caboose using 12vdc, the number will give you a bulb with the wattage and then it will just be a matter of getting a 36vdc bulb of that same wattage.

as Doc said, Star has them listed as 36 volts and all the markers in cars with 32 volt systems I have worked on use 36 volt bulbs.

Yes, 32V is the nominal or theoretical voltage of the battery. With the charging system operational, voltage will be as high as 37-38V. Of course, for safety reasons you want the thing to work properly at battery voltage.

Similarly, the nominal voltage of a car battery is 12V, but the electrical system is actually running 13.8 volts. Some USB chargers require the higher voltage to charge your phone, and will maddeningly shut off if the engine is not running.

When an incandescent bulb gets less than its rating, its power consumption reduces by the difference squared. For instance if you have a 100W bulb, and run it on 32 instead of 36 volts, its effective wattage is

100 * 32/36 * 32/36.

This can sometimes amount to more than you'd expect.

With LED bulbs, all bets are off. A resistor-limited LED will dim, either like an incandescent or more sharply. Some have an electronic buck or boost converter that will convert a range of input voltages to exactly what the LED needs. The LED will be exactly the same brightness as long as voltage is within that working range.

At Septa the SL-IV's use bulb part # 30S11 - 32V -DC. They are 30 watts and made in China. No manufacturer name on the box. I can tell you the marker light bulbs last allot longer than the headlight bulbs. If you Google the part # it brings up a ton of hits.

Doing some digging on the 30S11 part number- make sure when you search you also put 32v in the search bar. The part number must just be for the style of bulb, because you can get it in 12v, 24v, 32v, 75v, and 120v.

If you want the 30S11 in an LED here's http://normanlamps.com/LEDs/bi-pin-spec ... 3000k.html .

For the incandescent version here's http://normanlamps.com/30s11-32v-dc.html ...mld