Year of light under $12... : LUSENET : TimeBomb 2000 (Y2000) Preparation Forum : One Thread

and under $30 at least if you can not manufacture your own LED bulb.

I know that LED flashlights and replacement bulbs have been discussed here before and will probably be again, but I got to playing around and got really excited with my results. The white LEDs are normally run off of 3 alkaline cells or 3 nicad cells with a resistor sized to get their rated brightness. Used like this the 3 alkalines will last almost a month for 1 LED, a week or more with 3 LEDs in the bulb. There are however many situations that do not need rated LED brightness, or a search and rescue spotlight, just not DARK.

Here is what I found. I have a 2 AA flashlight with alkaline cells that have run a single white LED bulb I made (with 47 ohm resistor) for over a month. 2 D alkaline cells will last 6 months or more of continuous on. That is about a year of not-black nights on a single pair of D alkalines. About 700 hours on AAs. Every white LED I have tested so far will do this. (OddOne, have you tried this trick? Running the white LED on about 2 to 3mA?)

The 3 white LED bulbs available at,,,, and others will also run on 2 alkaline cells but for only about 1/4 of my single LED time according to a couple of sources, but I have not verified this for myself. More light, less time. Unlike regular incandescent bulbs, the color of the LEDs stays white even with the lower power.

Used in this manner, the light is VERY DIM compared to what we are used to. Even I complained about my dim light. Of course, I will still be complaining about DIM all the way into June on a single battery set, instead of complaining about no light at all. (which would you rather have to complain about?) It lights up a bedroom or bathroom sized space so you do not trip, can find things, see if the lid is up or down, read things a few inches away from the LED, show where the big lantern is when needed, things like that. (Almost sounds silly? Yep. but this is much less silly than losing civilization over 2 lousy digits!)

This is not meant to e anybody's main light. This replaces the night light we have plugged in the hall outlet or the light we now leave on in a bathroom. This beats fumbling for matches in the dark any day. The bulb will outlast at least 1,000 regular flashlight bulbs since they are aout all rated for only 10 to 50 hours (a $700 savings right there), and the battery savings is almost as impressive.

In fact, a 4 watt night light bulb on continuously costs a penny a day at $.10/kWh. That is almost exactly what the battery costs would be for this 2 cell D light if the batteries cost $.85 each. If you leave on a larger light now, this would save you money today.

I have found that most 2 D cell flashlights can be used. Also the 2 D cell Closet Light available from some Wally Worlds works very well, and so my bathroom should be not-dark for many moons to come. (oops, ok, a bit too crass.) This closet light comes with a screw-in bulb but the regular flashlight type bulb will push in quite nicely if you are not going to build a screw-type yourself or have one custom made. (Yes, I could do one for you, but that is not the point I am about here. so could Holly Solar or others also if you asked them nicely.) Advantage of using a regular bulb base with 47 ohm resistor: can be put into 3 cell flashlight for greater brightness if needed. Disadvantage, can be re-allocated permanently. (Tell them to get their own bulb.)

Cost: Wally's Closet Light or other cheap flashlight ~$2.50. Parts for LED bulb ~$3 to $7 depending on source. 2 alkaline D cells hopefully $.85 or better. Manufactured bulb $12 to $32 depending on source, number of LEDs, color of LEDs, etc.

-- tree (, December 11, 1999


My mother in law is not to be trusted with oil lamps or candles as she is too tipsy and has a tendency to fall asleep in front of the TV at night. So we got her one of those solar candles at Lowes. It has an LED bulb. Being in Florida, we use a lot of solar at our house. This works great as it will light up her whole area and down the hall to the bath. May have to get another one for the bath itself. Due to a stroke and terrible arthritis, a flash light is also hard for her to manage. They cost $15 at Lowes and provide light for 10 hours.


-- Taz (, December 11, 1999.

Thanks for that info Tree. I am sure that it will help a lot of people.

-- Ken Seger (, December 11, 1999.

Get Nichia brand white LED's or lights that contain them. Some outfits use lamps from Chicago Miniature lamp which are far inferior to the Nichias. I believe Bill at Holley is one of them. I got in on "Odd One's" last bulk LED buy for my LED's. The superbright yellow 10mm LED Radio Shack sells, something like 11 candella, makes a very decent light as well.

Hacked together a small outside light last night using 3 of the Nichias. I left the leads long so I could bend and individually aim each LED; one toward the doorstep and one each pointed in opposite directions on the driveway.The lamp consumes 12vdc and about 1/3 of a watt. This gives me at least a "navigation" level of lighting out a hundred feet or so in each direction. I already have compact fluorescent spotlights (18watt, equivalent to 75watt incandescent spots) but this LED light will run for 100 hours on the power two of the spots use in 1 hour.

Sometimes too much light can be a liability as well.

-- Don Kulha (, December 11, 1999.

Light at night might be a luxury. Use it sparingly or you'll attract attention. I bought some nice little flashlights at the doallr store for $1 each. I have others, too, plus a lantern to read by, etc. But too much light is not necessary.

-- Mara (, December 11, 1999.

I bought some of Odd One's white LEDs, and two comments: these are *BRIGHT* -- I'm talking near-laser brightness. You can NOT look into one that's on, and I am *not* exagerating. They are *that* bright. The other comment: they will not work on two cells, no way, no how, ain't gonna happen. They *will* fire to beat the band on three nicads, though, which has me planning on buidling a couple of "lanterns". I will put three nicads in the base, a white cone (pointy end down) above the base, and a ring of a few LEDs around the cone, facing up, and slightly inward. This should give me nice, soft, indirect lighting. On top of the lamp, I'll put a small bank of solar cells.

I figure a day on the windowsill should give me as-needed light during the night.

-- Ron Schwarz (, December 12, 1999.


Have you actually put one of those LEDs across 3 alkaline cells to see if it lights? I have not tried that one because I missed the bulk buy (Doh!!!) If it will not this is the first LED I have heard of that absolutely will not light DIMLY at least on 3 volts. It is a lot dimmer, and you may not have been able to see it in a bright light. Is it possible you could doule check for me in a dark room? I am seriously interested in the result and would appreciate it.

-- tree (, December 12, 1999.


I meant to ask if you have tried it across 2 cells, not 3. Sorry for the confusion.

-- tree (, December 12, 1999.

Yes, I tried. Zero light. Absolute zero.

-- Ron Schwarz (, December 12, 1999.

Some LED notes:

If you're willing to deal with yellow light, Radio shack sells a jumbo yellow LED that only costs $2.95 and is actually brighter, than the white LEDs that I have been able to track down (6000mcd for the yellow as opposed to the 4000mcd, that I've seen on the white). The light is very bright, but it is of course, yellow.

Another cheaper idea, if you're building an array - I took an old camping lantern and did an array of different color LEDs (Yellow, green, red). The net effect is that of a strand of colored christmas lights. The reson for this, is that white light, is actually made up of all the other colors. RS has a variety of LEDs, all fairly cheap. Just be careful to get LEDs that have the same ratings. The jumbo yellow, green and red sold by RS are compatible.

With the camping lantern idea, you are making room lighting, not a flashlight, so it actually works best if you don't try to aim the LEDs in the array all in the same direction. I scattered mine; all aiming in diferent directions at the plasic lampshade, that came with the camping lantern, which acts as a diffuser. It's actually darned cheery, which is a concept not to be underrated, in the gloomy times to come :-/

Also, I filled the box for the standard 6 volt lantern battery, with three battery holders (each holding two D cells), wired in parallel. This way, I can still use it, even if my stock of batteries starts to get low. As long as I still have two functioning D cells, it will still work.

Something that people might have missed: Use alkaline batteries for your LED lights, not NiCads or other rechargeables. The reason? Rechargeables tend to lose their charge, rather quickly, just setting on the shelf. So your LED flashilght, if you use rechargeables, will be dead in a couple of days to a week (depending on how new and high quality your NICads are), even if you haven't used it. Using rechargeables defeats the purpose of using LEDs in place of regular incandescent bulbs. Use your rechargeables for other high current drain devices, such as radios and regular flashlights.(Note - I've never tried the rechargeable alkalines, so I don't know if the rapid loss of charge problem is true of them, as well)

Also remember that resistors also use up some of your juice. You're better off with only two batteries, and a smaller resistor. 10 ohms is sufficient. RS doesn't sell a 10 ohm resistor, with a 1/4 watt rating, so just parallel to 22ohm 1/4 resistors, to get 11ohms. If you don't know what I mean by paralleling them, lay the resistors side by side, and twist the wires together, so the juice has to go through both resistors simultaneously to get to the LED (Hope that's understandable).

Standard disclaimer: No I don't work for the Shack, just mention them as a parts source, since for most of us, that's the most accessible electronics store.

-- Bokonon (, December 13, 1999.

If you are willing to put up with yellow light...

In my experience, teh white is more useful even when very noticeably dimmer just ecause it is white light.

But if you are wanting raw power in yellow, the better bang for the buck would be the 8000 mcd 5mm from Hosfelt. they are more like a dollar and a quarter each. about a 5 foot circle at 25 feet away. The 4000 mcd green from Hosfelt is neat, but I was a little disappointed. The best "colored" LEDs I have seen are the ones used by the Photon Microlight. I bought a blue and an aqua from them that have continued to amaze me. The yellow microlight with a little 200mAhour battery outshines 2 or 3 Hosfelt yellows and runs for 4 or 5 days like that. However, they charge more like $7 a piece for just the LED.

-- tree (, December 13, 1999.

the 7000mcd White from Hosfelt kind of gets the best of both worlds. too

-- tree (, December 14, 1999.

Have now found 5.6 candle power for $2.50.

-- tree (, February 08, 2000.

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