Unusual lighting/wiring question

[Jack Olsen]

This is for the deck I'm building that's adjacent to the garage. (So feel free to ignore if it's too far off topic.) The idea is to have a few dozen candles out there, but never have to actually light a candle. So I'm drilling out some conventional wax pillar candles so I can seat a single battery-powered LED tea light inside each one. Here's a picture of the drilled prototype candle and a tea light.

And here's a link to a very 4-second video of the flickering LED effect.

It looks candle-like enough to meet with the wife's approval. So that's set. But the trick -- now that I've eliminated the need to light 36 candles every time we use the deck -- is to somehow power the candles in a way that doesn't involve changing the tea lights' batteries every 36 hours (or whatever their life cycle is).

Each light is powered by a single battery CR2032 lithium 3V (225 mAh) battery. My idea is to run two slender wires into each tea light, using a little adhesive (tape maybe) to create a positive and a negative contact, and then power the whole set (let's say 36 of them, for the sake of argument) with DC power.

So my first question is: is this possible? I'm assuming I can get a DC power source for the task. In fact, there's a box currently in place for a no-longer-used low voltage light setup for that part of the property. It puts out two 12V circuits with a timer to control it. It puts out 12V, 500 Watts max, allowing 10 25W bulbs on each of the two circuits.

Second question: could the 12V power supply feed these lights?

I figure so long as I can weatherproof the tea lights, the LEDs will last a very long time. Feeding them 12V from the house will make the whole setup pretty simple.

But the language of electricity is one I really don't speak. So I'm putting it out to the GJ brain trust.

 

[Zeke]

You'd need to step the voltage down to 3v. What can be used are called converters. Someone called them buck converters.

I have a set of 12 little lights that came with a remote. That makes it pretty simple. But, the life of the little batteries is still the issue you would like to conquer. Or, how about using a 3v AC to DC power supply?

 

[Higgins]

It's very dooable!

I think the biggest challenge is going to be making the connection to the candle for the DC connection. How about a large ring and a smaller ring on the candle, with apposing rings on the deck rail??

AL

 

[bdymnjm]

If I remember correctly you can wire 4 in a series , 3x4 = 12 volts. Maybe solder wires to the tea lights' battery contacts. Plug each set into a car power adapter type receptacle for easy moving around. I would want the rain water to drain out of the candles somehow.

That looks nice btw. I like the look of LED candles and lanterns but dislike changing the batteries.

 

[Zeke]

It's very dooable!

I think the biggest challenge is going to be making the connection to the candle for the DC connection. How about a large ring and a smaller ring on the candle, with apposing rings on the deck rail??

AL

Man, that's getting fancy. Jack will need some pin connectors at the very least. I saw some with 24 ga. wire which sounds about right.

 

[Stuart in MN]

If I remember correctly you can wire 4 in a series , 3x4 = 12 volts.

This should work, and since you already have a 12vdc power supply it's easy enough to try. Just wire each set of four lights in series, and then connect the sets in parallel.

 

[nehog]

You'd need to step the voltage down to 3v. ...

Gotta love old computer powersupplies! 3.3 volts (close enough for this application) and probably free if you look around!

 

[ernst]

Like Zeke said, you have to step the V down to 3V. In DC series circuits R adds. Four lamps in series would give you a voltage across the lamps of First - 12 volts, Second lamp 9 volts, third lamp 6 volts and fourth lamp 3 volts. You need 3 volts and a parallel circuit.
Ernst

 

[koditten]

Anybody get weirded out by that pic of the candles? I'm reading Jacks' post and the candles looked like they were getting bigger.

Maybe I just need some sleep.

sorry for the thread derail.

KO

 

[Alchymist]

Like Zeke said, you have to step the V down to 3V. In DC series circuits R adds. Four lamps in series would give you a voltage across the lamps of First - 12 volts, Second lamp 9 volts, third lamp 6 volts and fourth lamp 3 volts. You need 3 volts and a parallel circuit.
Ernst

4 identical lights in series would each see 3 volts - perfectly fine. One could also put a small resistor in series with each light and run it off 12 volts. They are led (?) and don't draw much current.

 

[Jack Olsen]

Thanks!

I'll have to see if it will be simpler to wire in parallel sets of four or to use something to step down the voltage to 3V from the source. Either way should be pretty do-able. I think the next step is to test-wire a set of four and see just how tricky it is with these particular lights.

 

[Steevo]

Jack,
These things are so low current that a small "wall wart" transformer from a discarded electronic device would be enough to power dozens of them.
Dig through your junk box/drawer of old chargers for electric razors, calculators, toys, etc. and I am sure you'll find one that is somewhere around 3 volts.
Trying to step down a high-capacity 12v transformer like a yard light unit would require a big diode with heat sink to shed the power. It is wasteful power-wise and more complicated than just finding a $1 plug-in transformer at a Goodwill store or in your junk pile.

 

[plow]

FWIW...........


http://ledz.com/?p=zz.led.resistor.calculator