# Converting 12V auto bulb to LED



## Pydpiper (Nov 1, 2005)

I was in a parts store today and seen a standard 12v car bulb (like brake light, turn signal..) push and turn style, in place of the filiment was 6 LED's..
This is the same bulb my camper uses for primary lighting, the LED's would be cooler which is a big bonus, but what about efficency?
Will that style of bulb be more efficent in the certain times the trailer is running on battery power? If it will be would it be hard to make?


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## PhotonWrangler (Nov 1, 2005)

A couple of observations - 

The six-to-9-LED taillights that I've seen are woefully inadequate in terms of both brightness and beamwidth. They're generally not DOT-approved and for good reason; they stink. While I was pretty excited the first time I ran across these, I've tried them and had to remove them. I was really disappointed.

There are some multi-LED assemblies that contain a cluster of LEDs mounted on the sides as well as the front to improve (widen) the beamwidth, but standard 5mm LEDs are still pretty dim for the job.

From a technical standpoint it's possible to mount a cluster of high-flux spider LEDs, Cree X-Lamps or Luxeons with appropriate current-limiting resistors to get the brightness up to an acceptable range. It's still going to be tricky to get the beamwidth within the same range as the incandescent that you want to replace. There's also the issue of surge protection; automotive electrical systems are terribly, terribly noisy and laden with huge transients, many of which can pop an unprotected LED.

Oh, and there's that pesky issue of DOT approval.


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## Pydpiper (Nov 1, 2005)

I would be using these lights for interior lighting, that style bulb is what fits into a standard room light in an RV. That is why I question the efficency, for instance, if running on battery power and I chose to leave the bathroom light on overnight would the LED cluster draw less current than the original filiment?


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## PhotonWrangler (Nov 1, 2005)

I'm sorry for misunderstanding your intended use, Pydpiper! 

Yes, the LED cluster would draw considerably less current than the equivalent incandescent. A 6 LED cluster would draw somewhere around 20-30ma if they're in series and probably around 120-140ma if they're wired in parallel. I'm guessing that the incandescent lamp draws at least 300ma, so that's a significant savings in current.


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## Pydpiper (Nov 2, 2005)

It must have been my wording..  
Thanks for the detailed info, I was pretty happy to see these things, there are times when runtime for a room light is pretty important..
Now I just have to figure out how to make them.. Would there be a resistor in there anywhere, or is it just the LED's?


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## lebox97 (Nov 25, 2005)

here is a site I use for ideas on interior and exterior 12V DC lighting for my camping trailer and other vehicles...

http://www.superbrightleds.com/1157.htm (there are several pages other as well)


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## yuandrew (Nov 25, 2005)

There will be a resistor in there. Maybe some good ones may use a regulator as well so it will be a constant voltage. Automotive voltages can go anywhere from 12 volts to 14 volts (when the engine is running and the alternator charges)

I've gotten a closeup look at a LED side marker light on a rental Uhaul trailer. It uses those square leds http://www.quickar.com/prodview.php?session=eCcznG6s&id=40 (2 of them in series) plus a 270 ohm resistor.

Anyway, most of those replacement LED bulbs I've seen are red in color. You'll probably want white in your RV.


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## hank (Nov 27, 2005)

I'm also working on lights for a camper (1969 Dodge poptop van). Right now I don't use any of the electronics-based lights with the engine running at all, but I'd like to avoid the worry about doing it.

I have some 12 volt LED lights (including a "desk light" import with a dozen white LEDs, that's meant to run off a 12V AC transformer) and a number of the little cold-cathode very thin fluorescent lights (see www.allelectronics.com for those lights and inverters).

The fluorescents are actually brighter and more useful than LEDs, being linear sources.

Has anyone got a reliable noise/surge protector I could build into the camper, for a separate 12V DC circuit that would protect LED lights?

How about something reliable to drop 12v to 5v, to power "USB" computer plug devices?


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## The_LED_Museum (Nov 27, 2005)

From my website, comes the following:


*7443 Refractor 13 High-Flux LED (Red) Stop/Taillight Bulb
(Purchased 09-15-05, tested 10-25-05)*

I purchased two of these on Ebay for $12.50 ($6.25 each) - though I no longer remember exactly *_why_* I purchased them. :/

These LED retrofit bulbs fit in wedge-base sockets (on 12 volts DC electrical systems) and are specifically designed to use the reflector already in your taillight housing.
They feature 13 high-flux ("spider") LEDs; arranged in five groups of two on the sides, and three at the top so that they'd be aimed directly out the taillight fixture.






Here is one of the bulbs in its feral state.





And here is an oblique view, showing the side and top LEDs.





And finally, here is one of the bulbs, lighted.
Consumes 152.3mA at 13.12 volts DC.


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## jaak (Feb 14, 2007)

Great concept but they don't cut it.... Seen a few, even with taller towers.

I was all over buying some, but I know a few people that have put them in, seen they aren't bright enough, and taken them out. It's a shame really, cause they do look great until you compare them to a regular bulb.

But I'm sure that will change shortly as higer lumen components are used.


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## ksonger (Feb 14, 2007)

well if someone mods some cree soft leds into camper lights i will buy them! the 6000k are to white/blue for comfortable illumination for me but something less would be great.

ken


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