Moonglow LED domelight

[b1shmu63]

The silver bullet now sports a solid state LED domelight. Aside from looking very "cool", it has the advantage of 80 percent lower current drain. If I work on the car during the day and don't notice that it is on, it doesn't drain the relatively small 12 volt battery. The standard 5 Watt dome light draws about half an Ampere, the LEDs draw about one twelfth of an ampere.

The light is made up from 3 white LEDs obtained from 3 UFO style keychain flashlights. (5 dollars CDN each) The leds are connected in series and mounted on a small piece of double clad fibreglass board. A 47 ohm resistor and a blocking diode limit the current and prevent reverse voltage damage. Two leds are pointed at the seats and one is pointed at the dash. The inside of the car looks like it is lit by moonlight.

Note the light level varies slightly when the motor is running due to the setup's sensitivity to voltage variations. Of course if the motor is runnig you can turn on the other two "map" lights.

An interesting variation on this would be to use coloured LEDs.

[Holicow]

Sounds cool, how about some pics? I wish I knew something about electrical stuff, at least in a practical way...

Hey, mine has 100% less drain. I leave it off . :P

[Resist]

Well my OEM dome light uses ZERO current draw. I keep it turned off, as I've done will all the cars I've ever owned. I hate being blinded by car dome lights at night and it isn't needed during the day.

[b1shmu63]

I have kept mine in the off position myself for years, mainly because I've had to jump too many cars (mine included) where the dome light has been left on. Sounds like red LEDs would solve the night blind issue for you.

I replaced mine with red LED's. Map lights are white LED's. I also ran wires down to under the dash where I put one red LED on each side pointing at the floor. Red doesn't screw up one's night vision the way white and other colors do. I also put red LED's in the rear hatch light. I bought all the LED's from superbrightleds.com. I'm quite pleased with the results.

[b1shmu63]

Thanks for the tip on superbrightleds. Sounds like a really nice installation! Do you use a resistor in series to control current? (I'm working on an active current limit circuit now.)

Originally Posted by b1shmu63

Thanks for the tip on superbrightleds. Sounds like a really nice installation! Do you use a resistor in series to control current? (I'm working on an active current limit circuit now.)

Yes. I started out with pre-made "bulbs" that are plug-in replacements, which already have resistors built in. But that wasn't bright enough, so I added bare LED's and resistors. I'd have to check the values I used, but it depends on current draw of the individual or cluster of LED's and the input voltage (12-14v). A single super bright LED generally consumes about 20 milliamps.

[james]

"...LEDs obtained from 3 UFO style keychain flashlights. (5 dollars CDN each)..."

I think you could do a LOT better on the price by getting new ones from an electronic parts supply

[b1shmu63]

Ma wee bit O Scotish blood sayd dunna dooo it ladee......Then in a moment of weakness, realising it was three and a half hours driving to the nearest electronics wholesaler.......I gave in.

Next time I'll order a bag of them online.

[ext1jdh]

If its at all possible, can someone post a schematic of this little baby? I've been wanting to get rid of the incandescents but I don't quite have the knowhow to throw one together without instructions.

TIA,
Joe