# driving at halogen bulb at a higher voltage?



## sphynx_000 (Apr 23, 2006)

I was looking at this,http://www.instructables.com/ex/i/9129E65EFFBE102880EC001143E7E506/?ALLSTEPS

Is there any way I could run 2x 7.2 volt battery packs to a 12 volt halogen light?


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## FirstDsent (Apr 23, 2006)

You have posted an incandescent thread to the LED forum. You will find the folks on the incandescent forum better informed on matters such as this. 

IMO, that's a lot of overdrive. 17% overdrive to be exact. May make a flashcube instead. It may be possible if you use a resistor to drop the voltage. If you just want to use that power pack, that may be your solution.

Bernie


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## sphynx_000 (Apr 23, 2006)

sorry, 

I forgot I was still in the LED section.


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## sphynx_000 (Apr 23, 2006)

FirstDsent said:


> You have posted an incandescent thread to the LED forum. You will find the folks on the incandescent forum better informed on matters such as this.
> 
> IMO, that's a lot of overdrive. 17% overdrive to be exact. May make a flashcube instead. It may be possible if you use a resistor to drop the voltage. If you just want to use that power pack, that may be your solution.
> 
> Bernie


 

what is a flashcube?


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## legtu (Apr 23, 2006)

Hmmm... I think it'll run just fine. MR-16's are usually underdriven at 12v and depending on current draw, there's also voltage sag.


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## sphynx_000 (Apr 23, 2006)

I think ill have to try that, being it will cost me almost nothing.

Anyways, how do i calculate the resister value to drop voltage?

EDIT: People on that link talk about using 14.4 volt battery packs with the light. Sounds like it works fine, and if not, no big loss burning up a 4 dollar bulb.


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## FirstDsent (Apr 23, 2006)

sphynx_000 said:


> what is a flashcube?


Well, you young whippersnappers wouldn't know I guess. Waaaay back in the 1970s, "110" cameras used a disposable flash cube because the compact strobe wasn't available in small/cheap cameras. They used a mechanical striker that ignited the flash. Eeach cube had four flashes, and rotated automatically when you cocked the camrea. I have to laugh every time I think about it. That wasn't that long ago!

Showing my age,
Bernie


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## Brighteyez (Apr 23, 2006)

That was my first thought when I saw your first post. How many people actually remember what a flashcube or flashbulb was? 

As age can contribute to premature dementia (!), I seem to remember that the flashcubes were well in use by the mid-late 60's as a replacement to the AG-1 flashbulbs. And I think they were more commonly used in 126 (square 35mm format) cameras well before the 110 cameras appeared on the scene. But I'm not so sure that my memory is all that good either  On the other hand, you know what they say about the 60's, "If you remember the 60's, you weren't there"  



FirstDsent said:


> Well, you young whippersnappers wouldn't know I guess. Waaaay back in the 1970s, "110" cameras used a disposable flash cube because the compact strobe wasn't available in small/cheap cameras. They used a mechanical striker that ignited the flash. Eeach cube had four flashes, and rotated automatically when you cocked the camrea. I have to laugh every time I think about it. That wasn't that long ago!
> 
> Showing my age,
> Bernie


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## Brighteyez (Apr 23, 2006)

Before you start, you may want to also take into consideration that many incandecent bulbs are already being overdriven in their 'recommended' voltage usage. e.g. a bulb being used in a 3 cell light (4.5 nominal voltage) may actually be rated for something in the 3.5-3.7 range, and many of the bulbs being used in the 2 cell CR123 incandescent lights are actually rated for less than 5V. 



sphynx_000 said:


> I think ill have to try that, being it will cost me almost nothing.
> 
> Anyways, how do i calculate the resister value to drop voltage?
> 
> EDIT: People on that link talk about using 14.4 volt battery packs with the light. Sounds like it works fine, and if not, no big loss burning up a 4 dollar bulb.


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## RoyJ (Apr 24, 2006)

Remember, 12V automotive bulbs are operating at around 14.4V when the alternator is running. Should be fine.


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## winny (Apr 24, 2006)

Overdriving a 12 V bulb to 14.4 would cause its lifetime to drop down to 0.0957 of its rated life. Unless it has got really short life at 12 V you should be fine.


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