LED's . . . . .

Here's another 'Oldie But Goodie' that I saved from the now-gone Plan For Pandemic site. (So glad that I keep such an extensive binder of info from sites!!)

EMERGENCY LIGHTING: THE LED SOLUTION

In recent years a revolution has taken place in the world of LED’s (Light Emitting Diodes), and we’ve seen advances in light output, the addition of bright white diodes, and a dramatic decrease in cost. While LED’s are not always the most efficient light source, they have major advantages in certain applications over other technologies.

During a power outage, many people are reduced to using flashlights, oil lanterns, and even candles for emergency lighting. Each of these has distinct disadvantages. Flashlights, and battery operated lanterns that use florescent or incandescent light bulbs eat up batteries at an impressive rate. Oil lamps are smoky, give off fumes, and a great deal of heat, which is not always desirable. And candles produce little light and are a fire hazard.

LED’s, on the other hand, produce light with very little current draw, the LEDs can burn for years without failure, they produce almost no heat, and no dangerous fumes. Their potential for generating a fire is practically nil. In many ways, they are the ideal low voltage light source. The only quibble with them, in my experience, is that they are primarily a low level light source.

LEDs have been available for years, and in colors, like Red, Green, and yellow, have been relatively inexpensive. The technology for producing White LED’s has, until recently, been much more expensive. But bright white LED’s are now reasonably priced, albeit still higher than the colored LEDs.

Over the years I have built a number of LED lanterns. They have served me well during power outages, and were very easy to construct. While you can purchase them already built, the cost of making them yourself is very low, and it makes for a fun project. You can also create light sources geared to your power sources, and that is a real advantage.

If you have a 12-volt deep cycle battery (typical 105 amp/hr) you could run a 4 LED lantern for more than 1200 hours before requiring recharging. A car battery, with a simple, low cost trickle-charging solar panel, would run as long as the battery remained viable, likely for many years.

Of course, LED’s are low-level light sources. You are not going to flood a room with LED lighting. You can read by them, and certainly navigate a darkened room with them, but the level of light you will get will approximate what a kerosene lamp might offer.

Construction is simplicity itself. You need to know the operating voltage of the LED, and that can vary from about 2.0 volts to 4.0 volts. Typically, 3 volts is common. And that works to our advantage. A pair of C or D cells will run a 3-volt LED. A 6-volt Lantern battery is a good fit for a duel LED setup, and a 12-volt battery fits nicely to a 4 LED array. If the voltages don’t match up to the power source, a resister can be placed in the circuit to adjust it down.

Most LED’s can be run within a range of voltages. Usually a 20% leeway. So a 3 volt LED will probably fire (light up) at 2.7 volts and tolerate 3.3 volts.

LED’s are Diodes, so current only passes thru them in one direction. This will be the only real consideration when wiring them up. LED’s have polarity, and you will have to examine the package they come in to determine the positive and negative leads. One will be longer than the other. You will wire them in series, negative lead to positive.

"In the event that the operating (forward) voltages of your LED array are less than the battery, you will need to put a resister on the positive lead of LED #1 in the series. This will reduce the voltage to within operational limits.

The formula for figuring the resistance is
( Source Voltage - LED Voltage Drop ) / Amps = OHMs

As an example, if you had a 6 volt battery and a 3 volt 20ma LED, and you wanted to know what size resistor to put inline to lower the voltage, you’d do the following calculation:
(6 – 3 ) / (20/1000) = 150 Ohms.

You will need to check the voltage and current requirements for the LED you select in order to make these calculations.

While you can simply have the LED’s hang from wires, it is much better to create an enclosure or case for this affair. I’ve used a wooden cigar box with a 6 volt battery inside, and a switch on the side, and the LED’s extruding from the top. I’ve also used metal Storage cans, Plastic Containers, and even cold cream jars (using a smaller AA battery pack) to create lanterns. Here, you limit is pretty much up to your imagination.
Most LED's are directional, while a few may emit light in all directions. Judicious use of reflectors and mirrored surfaces can enhance the flow of light.

For lanterns hooked up to a 12 volt battery, you don’t want to enclose the battery, just run leads (up to say, 6 feet) from it to the terminals. You will want to ensure a good connection to the battery terminals, and should quickly solder the wires and diode leads together. Too much heat, applied for too long, can damage the LED. If you accidentally reverse the polarity of any of the diodes, none of them will light, but you will probably not damage the LED. Tape and Test first, is always a good idea.

As always, when working with electricity of any voltage, use precautions. A 12 volt car battery packs quite a wallop, and you can arc weld with one if you cross the positive and negative terminals. If you are not comforatble with dealing with batteries, get assistance from someone who is. Always use a heavy enough guage wire to handle the current, and keep the runs (length) of wires as short as possible to reduce current loss.
Hope other's find this information of use. I personnally find LED lighting to be the best solution out there for low cost, low power consumption lighting. Best of all, LED's are cheap, and fun to play with.

Note: I have purchased LED's from the following source on the net. I am not connected in anyway to this company and can only say I was satisfied by my purchase. YMMV.
http://www.theledlight.com/ source: (http://planforpandemic.com/viewtopic.php?t=1041)

LED lighting whether battery operated or electric is the most cost effective way to light an area. I buy all my LED light bulbs at dollar tree, only $1.00/bulb compared to spending $3.00 or more for one light bulb. My entire house, garage, camp, etc. use these $1.00 LED bulbs, they last up to 25,000 hours of burn time. It may take a minute for the link to come up, so be patient:


https://www.dollartree.com/warm-white-8-watt-medium-base-led-lightbulbs/244270

Beware that the cheap LED bulbs that you screw into 110 volt sockets are cheap for a reason...they tend to skimp on the heat dissipation, so the circuitry to drop the voltage from 110 down to the LED operating voltage will tend to overheat and burn out MUCH faster than the LEDs by themselves would last.

Battery operated LED lights don't suffer from this because they don't need voltage conversion circuits.

dmwalsh568, I thought for only a buck they wouldn't last a year, I checked my log and I'm on my 4th year without any of the bulbs burning out, can't tell ya how many hours they burned though.

I guess I'm just lucky on this purchase, plus my electric bill dropped a few dollars a month. I have 4 dozen in storage, just in case they start burning out.