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Thread: Building a Portable Fog Light/Roadside Light

  1. #1
    Flashaholic* ericjohn's Avatar
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    Default Building a Portable Fog Light/Roadside Light

    Now I am just dreaming at this point, but I would like people's opinions on the feasibility of this:

    I would like to take a 12 volt fog light bulb (or the whole module if necessary) and power it on 2 908 or 918 cells wired in series. I will also need a switch and a body (screw-top or box is fine, I'm not picky. This will mainly be as a toy, but I could see some pratical uses for it. Are there still 6 volt automobile bulbs being made at all or were they completely discontinued. I've seen some auto bulbs at the grocer I used to work for but cannot remember if they were 12 volt. Modern car voltage is 12 volts (correct me if I'm wrong.)

    I am wondering if anyone else has tried this and is it easy enough? Also what is the brightness and runtime I can expect?

    I am welcome to all answers...
    "When egrets take flight, foul weather in sight."

  2. #2
    Moderator Alaric Darconville's Avatar
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    Default Re: Building a Portable Fog Light/Roadside Light

    Quote Originally Posted by ericjohn View Post
    I would like to take a 12 volt fog light bulb (or the whole module if necessary) and power it on 2 908 or 918 cells wired in series.
    An automotive fog lamp can be designed around many different 12V automotive bulbs, such as the 9006, H3, H1 (and many other kinds, like the 9145). By "fog light bulb" do you just mean the miniature bulb itself? And do you mean for that bulb to be yellow (based on a a common myth about fog and yellow light)?

    The 908 and 918 are 6V batteries, not cells. They themselves have 4 smaller 1.5V cells inside them, totalling 6V (in the 908, those are "F" cells, typically). The Duracell MN918 is a 26AH (amp-hour) battery1, and so a pair of them in series would be 12V, 26AH.

    There's not really a direct conversion between amp-hour and runtime if the load is particularly high-- a 9145 (nominally 45W) would need 3.75 amps at 12V to approach the brightness it'd get in a car (since car voltages are higher than 12V); you're not going to get anywhere near even 6hrs of runtime at any appreciable intensity despite the math looking like you should.

    1The capacity claims vary from site to site. This .PDF from Duracell might be of interest.
    Last edited by Alaric Darconville; 02-17-2015 at 04:33 PM.

  3. #3

    Default Re: Building a Portable Fog Light/Roadside Light

    Quote Originally Posted by ericjohn View Post
    Are there still 6 volt automobile bulbs being made at all or were they completely discontinued
    Yes, available but they aren't very... impressive. The 6 volt headlight bulbs I have are 35 watt/35 watt dual filament. Without overdrive, they are pretty sickly yellow. About 80% of my flashlights beat the crap out of them. If you go this route, get the biggest reflector you can find... you'll need it.

    The non-headlight 6 volt vehicular bulbs are even worse.

    It's pretty awesome when a Vinh 10440 singe cell light is better than an antique 6 volt headlight.
    Last edited by more_vampires; 02-17-2015 at 04:56 PM.

  4. #4

    Default Re: Building a Portable Fog Light/Roadside Light

    6v halogen bulbs of types widely used in fog lamps are no longer common, but are not yet extinct. H1 and H3 can still be found, and they produce very usable amounts of light. The "6v, 55w" H3, for example, produces 1050 lumens +/-15% at 6.3v with a maximum power consumption of 63 watts. The "6v, 55w" H1 produces 1350 lumens +/-15% at 6.3v with max power consumption of 63w. Light output won't be your big problem, power draw will be.

    more_vampires' "sickly yellow" weak lamps are that way because of the particular bulb design he's using, not because they're 6v and not because 6v bulbs are intrinsically "sickly yellow" or weak. 12v versions of the 35/35w bulbs are not much better. Still, he's got a point; this is old-time technology and while it is simple, today's LED options are quite a bit less power-hungry. That said, there are no ready-to-go automotive-type 6v LEDs or modules.

  5. #5

    Default Re: Building a Portable Fog Light/Roadside Light

    When the charge system kicks in 7.2-7.3 volts, my BA20D 6v bulbs whiten up a bit. With overdrive and lighting both filaments at the same time, they're actually not bad at all. Running both filaments at the same time for long periods will kill them, though.

    No one is expected to hotrod antique tech when you can hotrod modern tech for your non-vehicle application.

  6. #6

    Default Re: Building a Portable Fog Light/Roadside Light

    Quote Originally Posted by more_vampires View Post
    lighting both filaments at the same time, they're actually not bad at all.
    This is a bad idea.

    Running both filaments at the same time for long periods will kill them, though
    No, it won't. The filaments will be just fine. But you're throwing a 100% electrical and thermal overload on their common filament support, and on the common/ground leg of their circuit. Good recipe for problems.

    What archaic lamp are you running BA20d-base bulbs in, and which bulbs are you running? There are some halogen ones you can get from this outfit, but other than that the majority of BA20d-base bulbs aren't halogen.

  7. #7

    Default Re: Building a Portable Fog Light/Roadside Light

    Yeah, as I said it'll kill them fairly quickly if you do that. I've fixed the wiring for some folks who did that in their quest for more output.

    "I keep killing headlight bulbs, will you take a look?"
    "There's your problem right there. You're not supposed to do that."

    Archaic lamp: Bosch reflector, BMW bucket. Legit reflector and Bosch lens, for what it's worth. I'd say about 1/5th of the electric problems I've seen are from some guy trying to MacGyver their headlight with whatever they could scrap up. I absolutely do not recommend this on a vehicle. For a portable handheld made from "lol vehicle parts," it should work for a burst/turbo mode.

    I have a fat stack of halogen BA20d. They're a little better than non-halogen, yeah. The problem is antique charging and electrics just plain can't support a wattage increase at all. There are 12 volt conversions and 12 volt BA20d that give you spare wattage, there are H4 dropin conversions.

    I'm not a fan of the H4 conversions I've found, I do not trust them. The H4 dropin would definitely work though... for a hacked handheld non-vehicle light.

    Safety first.
    Last edited by more_vampires; 02-19-2015 at 09:41 AM.

  8. #8
    Moderator Alaric Darconville's Avatar
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    Default Re: Building a Portable Fog Light/Roadside Light

    Quote Originally Posted by more_vampires View Post
    The problem is antique charging and electrics just plain can't support a wattage increase at all. There are 12 volt conversions
    The 12V conversions are great-- wiring hardy enough to withstand the high current associated with low voltage (for example, headlamp wiring) will be more than enough for a 12V circuit. (Going from a positive ground to a negative ground can adversely affect other items, such as the radio.)

  9. #9

    Default Re: Building a Portable Fog Light/Roadside Light

    Quote Originally Posted by more_vampires View Post
    Archaic lamp: Bosch reflector, BMW bucket.
    Motorcycle...?

    Legit reflector
    How old is the reflector? Has it ever been restored? If so, how?

    there are H4 dropin conversions.
    Complete lens + reflector H4 drop-in, could work. H4 "drop-in" conversion for BA20d bulb, not so much.

  10. #10
    Flashaholic* ericjohn's Avatar
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    Default Re: Building a Portable Fog Light/Roadside Light

    Quote Originally Posted by Alaric Darconville View Post
    An automotive fog lamp can be designed around many different 12V automotive bulbs, such as the 9006, H3, H1 (and many other kinds, like the 9145). By "fog light bulb" do you just mean the miniature bulb itself? And do you mean for that bulb to be yellow (based on a a common myth about fog and yellow light)?

    The 908 and 918 are 6V batteries, not cells. They themselves have 4 smaller 1.5V cells inside them, totalling 6V (in the 908, those are "F" cells, typically). The Duracell MN918 is a 26AH (amp-hour) battery1, and so a pair of them in series would be 12V, 26AH.

    There's not really a direct conversion between amp-hour and runtime if the load is particularly high-- a 9145 (nominally 45W) would need 3.75 amps at 12V to approach the brightness it'd get in a car (since car voltages are higher than 12V); you're not going to get anywhere near even 6hrs of runtime at any appreciable intensity despite the math looking like you should.

    1The capacity claims vary from site to site. This .PDF from Duracell might be of interest.
    Thank you VERY much. This is still in the "dreaming phase" and no where near the financing nor the researching for needed materials. Hopefully I can figure something out...
    "When egrets take flight, foul weather in sight."

  11. #11
    Flashaholic* ericjohn's Avatar
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    Default Re: Building a Portable Fog Light/Roadside Light

    Quote Originally Posted by more_vampires View Post
    Yes, available but they aren't very... impressive. The 6 volt headlight bulbs I have are 35 watt/35 watt dual filament. Without overdrive, they are pretty sickly yellow. About 80% of my flashlights beat the crap out of them. If you go this route, get the biggest reflector you can find... you'll need it.

    The non-headlight 6 volt vehicular bulbs are even worse.

    It's pretty awesome when a Vinh 10440 singe cell light is better than an antique 6 volt headlight.
    All right thank you very much for your input. Those are some good things to consider...
    "When egrets take flight, foul weather in sight."

  12. #12
    Flashaholic* ericjohn's Avatar
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    Default Re: Building a Portable Fog Light/Roadside Light

    Quote Originally Posted by -Virgil- View Post
    6v halogen bulbs of types widely used in fog lamps are no longer common, but are not yet extinct. H1 and H3 can still be found, and they produce very usable amounts of light. The "6v, 55w" H3, for example, produces 1050 lumens +/-15% at 6.3v with a maximum power consumption of 63 watts. The "6v, 55w" H1 produces 1350 lumens +/-15% at 6.3v with max power consumption of 63w. Light output won't be your big problem, power draw will be.

    more_vampires' "sickly yellow" weak lamps are that way because of the particular bulb design he's using, not because they're 6v and not because 6v bulbs are intrinsically "sickly yellow" or weak. 12v versions of the 35/35w bulbs are not much better. Still, he's got a point; this is old-time technology and while it is simple, today's LED options are quite a bit less power-hungry. That said, there are no ready-to-go automotive-type 6v LEDs or modules.
    I'm starting to see that my project isn't very feasible. I do however, appreciate the information...
    "When egrets take flight, foul weather in sight."

  13. #13
    Flashaholic* ericjohn's Avatar
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    Default Re: Building a Portable Fog Light/Roadside Light

    Thank you everyone for your input. When I get a chance I will write all of this information down and see what I can do.

    Are there any high capacity 12 volt batteries that can also be portable and possibly rechargeable? I mean besides those in the Q-Beams?
    "When egrets take flight, foul weather in sight."

  14. #14
    Moderator Alaric Darconville's Avatar
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    Default Re: Building a Portable Fog Light/Roadside Light

    Now, THIS guy is something my grandfather had. It used a screw-top battery and so the battery itself was directly exposed. The front of the lamp was a sealed beam, the back end used a replaceable bulb and had a flasher function.

    They don't make 'em like they used to! (They also don't run down batteries like they used to.)

  15. #15

    Default Re: Building a Portable Fog Light/Roadside Light

    Quote Originally Posted by -Virgil- View Post
    Motorcycle...? How old is the reflector? Has it ever been restored? If so, how?
    Yep. Reflector is 5 yo, replacement lens from BMW Mobile Traditions themselves. Not aftermarket, OEM. To be worth restoring a reflector, the bike would need to be pre-1950 at least.

    Quote Originally Posted by -Virgil- View Post
    Complete lens + reflector H4 drop-in, could work.
    Yeah, reviewed a couple of them. Compared to OEM, wasn't worth it. IIRC, it was like an $8 savings.

    Quote Originally Posted by ericjohn View Post
    Are there any high capacity 12 volt batteries that can also be portable and possibly rechargeable? I mean besides those in the Q-Beams?
    Yep, but you'll need a funky charger. Lithium iron, like Shorai. I have two just for fun and testing.
    http://shoraipower.com/batteries-c41
    They have the advantage of a nice light weight.

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