Homemade emergency LED Lantern - looking for ideas

Last night we had a good long power outage. Despite numerous flashlights saving the day (night?), I felt what I need now is a bunch of small LED "lanterns" to scatter around the house to provide light during these emergencies. Sure, flashlights work, but it'd be nice to have a stationary light in each bathroom, in the hallway, on the stairs, etc.

I think this would be a nice fun project for me and my boys to work on. What I'd like to end up with is around 10 little lanterns, each with one or more LED's, a switch, and a big enough battery pack to allow them to run for, say, 48+ hours non-stop. Something similar to the Surefire Hurricane lights. I know I can just wire up an LED, a 100 ohm resistor, and a pair of batteries, but I'm looking for any suggestions on what might be better, what specific parts to use, etc.

If this has been covered before, I apologize - I wasn't quite sure what to search on.

Thanks!

Re: Homemade emergency LED Lantern - looking for i

Ah ... if you go for a little lantern in the size of an Arc LS powered by a CR123 I am all ears !!!
For reference: with a Wiz2x2 driver the McLuxIII achieves 42h regulated burntime at 30mA which is plenty bright for the purpose you are looking at ... and a 2-stage lantern would be so cool!
bernie

Re: Homemade emergency LED Lantern - looking for i

I took one of the 4-AA Kids lanterns from walmart.

Removed the reflector

Cut out a piece of bud board to press fit in the dome of the lantern.

Soldered an array of resistored LEDs (8) onto the budboard (one resistor for every two LEDs in Parallel. (about 20-30 mA each)

Ran wires to a hollowed out PR base bulb that I put in the lamp base.

Works great.

Changes if I were to do it over.

1. Grind down about half of the LEDs to make the light more omnidirectional.

2. Use 26K LEDs

3. Probably drop number of LEDs to 6 with the brighter LEDs OR reduce current to no more than 25mA per LED.

wwglen

Re: Homemade emergency LED Lantern - looking for i

A second type I made used a 9 volt battery with two leds in series with a limiting resistor.

wwglen

Re: Homemade emergency LED Lantern - looking for i

A while back, I took a 2D plastic light, and cut it down to 1D size,
and jammed an Arc AAA head in place of the bulb.
Plenty of light in a room with night adapted eyes, and it will run about 60+ hours /ubbthreads/images/graemlins/smile.gif

You may want to look into some thing like that.
The 1D size isnt bad either, especially to sit on tables etc.

Re: Homemade emergency LED Lantern - looking for i

You can also buy cheap 4AA taplights and mod them with some LEDs and resistor them. I think the biggest obstacle to a cheap light is the battery holder/host, once you have that modding it for LEDs is fairly easy. I suppose the cheapest thing to do may be to find some 4AA holders with 9v clips on them and wire LEDs resistors and a switch into the clip.

Re: Homemade emergency LED Lantern - looking for i

ah yea, the taplights are a good idea

they hve packs of them at my local walmart really cheap.
thought about modding those myself also.

Re: Homemade emergency LED Lantern - looking for i

How's this for a home-made emergency light.
I build models as a hobby and just recently finished my "Enterprise NX-01" which I lit with about 35 LED of various types. This LINK is not my model but is a good writeup that will give you an idea of what I did.

The model is nearly two feet long and with all of the LEDs lit it does a pretty good job of lighting up an entire small room (especially the engines). It will also run for about 10 hours on 4 "AA" rechargable NiMH batteries.

Worked VERY well as an area light during the last power outage. Not that I have any shortage of other lights available....but this was FUN! /ubbthreads/images/graemlins/smile.gif

Re: Homemade emergency LED Lantern - looking for i

I'm not quite sure what a "taplight" is - are those the little battery-operated lights designed to stick up in a closet?

I wasn't really thinking of modding an existing light, but that may be a good idea. My original thoughts were just to buy some sort of battery holder, then take the LED(s)/Resistor(s), solder them all together, and maybe goop some epoxy over it to hold it all to the battery holder. Ugly, but cheap and functional.

What would any of you recommend in terms of the actual LED to use? And is there a chart somewhere to show what amount of resistance I'd need for these LED's for various voltages (primarily what would I need to use if I went with 2 1.5v batteries versus using 4 1.5v ones)?

And where can I get these parts cheap?

Thanks again, all these suggestions are great. /ubbthreads/images/graemlins/smile.gif

Re: Homemade emergency LED Lantern - looking for i

What I don't recommend...



Broke every rule in the book to build that one. Ran for nothing short of three hundred hours - and that was because I started with 50% depleted cells. Yes, that THING is direct drive without a single resistor in sight.. /ubbthreads/images/graemlins/naughty.gif No there is no switch. The wires were terminated and it was left to run as a battery eater. With 4 x 26k mcd LEDs, it turned out to be pretty DARRRRRRRN bright!

I am currently playing with a 8mm and 10mm LED. The 10mm has a very nice omnidirectional flood, claims to produce 15 lumens at 150mA. D cells have ~28000mAH of capacity at a 0.75A discharge rate, so it's safe to assume you will get even more.

If you have a plastic jar lying around, it would be fairly easy to cut holes in the lid for the LEDs and a switch. Put the battery pack in the jar itself. This makes for an inexpensive, easily modified host. Pot the LEDs in epoxy, use the right switch and it could even be water resistant although that seems unlikely to be necessary.

Re: Homemade emergency LED Lantern - looking for i

depending on how much work and how complex you want it. 1 way would use dorcy parts, ie dorcy board and LED. connect this to a single 'C' or 'D' cell and install into something. LONG running and bright. Next would be PVC. Most of the 20k and 26k mcd LEDs run decientally bright right off of 2x batteries. I have some 20k's that pull 15mA on 2 used 'AA's. If you sand down the tops of the LED's you can get nice flood lighting. Get some PVC tubing that will hold the Batteries you want to use, get some flat pipe caps. Put the LED in a hole on one side, and solder in a battery with a small switch. Or find a simple way to have it turn on when the battery is installed. 10,000mcd is pleanty bright to flood a room for navagation reasons.
Jeff

Re: Homemade emergency LED Lantern - looking for i

The Dorcy driver seems to be able to handle 3V+ so I'd consider a 2"D" flashlight as the donor with the Dorcy driver and then 2 26K or Nichia. As long as you draw under 100 ma, you'd have abou 180 hour runtime

Re: Homemade emergency LED Lantern - looking for i

Assuming a 3V Vf you get the following currents in Amps. To get mili-Amps just multiply by 1000. Example .12 Amps = 120mAmps

Resistance VOLTAGE
....3....3.6....4.5....4.8....6
5...0....0.12....0.30....0.36....0.6
10..0....0.06....0.15....0.18....0.3
15..0....0.04....0.10....0.12....0.2
20..0....0.03....0.075...0.09....0.15
25..0....0.024...0.06....0.072...0.12
30..0....0.02....0.05....0.06....0.10
35..0....0.017...0.042...0.051...0.085
40..0....0.015...0.037...0.045...0.075
50..0....0.012...0.03....0.036...0.06

Voltage ==> Batteries
3 ==> 2 Alkline
3.6 ==> 3 Rechargable
4.5 ==> 3 Alkline
4.8 ==> 4 Rechargable
6 ==> 4 Alkline or 5 rechargable

Now this is off a little bit because even at 3 volts you will get some current through the led's 2-15mA but as the voltage goes up the currents shown are pretty close.

wwglen

Re: Homemade emergency LED Lantern - looking for i

I have used the dorcy "AA" boards with 3v to run LUX I's at spec power.

Frank, do you need white light? If not, then the answer is amber. Lumileds makes super-flux amber LED's with a drive current of 70ish mA. These can be found on ebay. These will use a 10ohm (around there) resistor and 2x alky batts. This would/could be decientally bright, have NO electronics (aside from the resistor and some kind of switch).
Jeff

Re: Homemade emergency LED Lantern - looking for i

If you don't mind modding you can also use almost any 4AA light as a host and replace the bulb with LEDs somehow. If you have some biglots you may be able to find the energizer 2led lanterns or energizer accent lanterns for about $3 each, the accent lanterns come 3 to a box. I have spent time trying to find the cheapest way to make a decent AAA or AA based LED light. The host has to be 3 or 4 cells otherwise you have to go with a boost circuit or lithium batteries which drives the cost up. My goal was originally to make a bunch of $2 LED lights as easily as possible but most of the flashlights in the stores using more than 2 cells are either already LED, take 3D cells and cost $15 or more or are lanterns costing more than $3. Taplights come in 2 or 4 cell varieties and vary on the quality of construction also. Some are cheezy with a crummy switch so beware of that. The advantage of a taplight is in a power outage you have a huge pushbutton so to speak so you can put it somewhere and find it fumbling in the dark easily. They also use plastic that diffuses the light however I found the type with a white inner reflection surface with the LEDs bouncing backwards off it works the best for light dispersion.

Re: Homemade emergency LED Lantern - looking for i

We made a couple of emergency lights using a 9V batt inside a round Kodak film canister, 1 LED, 1 resistor, and a switch. It's decently bright for emergencies, and we've had it for over a year; use it almost nightly to read to my son.

Re: Homemade emergency LED Lantern - looking for i

My current project is this. Go to www.worldtorch.com ...there they sell a boost circuit kit. I have been building a few of these...substituting a 26k white LED for the one that comes with their little PC board. Pick up a Rat Shack C or D single cell holder. Assemble evrything into a pill container from the drug store and drill a hole for the led to stick up through.
I've been using batteries that just won't work in flashlights or my boom box and they will run this little light for about 2 to 3 months. I now have one of these in each of my bathrooms on a shelf. They make perfect night lites. I actually used them both the other night when our power went out..very hot day. They were more than enough to navigate around the house....and they're dirt cheap!!! /ubbthreads/images/graemlins/happy14.gif

Re: Homemade emergency LED Lantern - looking for i

Great suggestions everyone!

GreenLED - what LED and what size resistor did you use?

I'm particularly interested in that WorldTorch option - seems to perfectly fit my need and the "kit" aspect to turn this into a learning project for my boys.

Unclearty, do you have any idea/estimate how long that light would run on a single C or D cell? I see they sell two circuits - a boost one and their "original" which appears to have some regulation, but seems to require 3+ volts.

Re: Homemade emergency LED Lantern - looking for i

A USED D cell is giving around 2-3 months of light using the boost circuit. It's really quite impressive with a 26k led. The last one I made, I used a micro toggle switch in the lid of the pill bottle. Now when I get up in the morning, I turn it off, and back on in the evening. I'm guessing that I won't have to replace the battery till late September!

Re: Homemade emergency LED Lantern - looking for i

I would say get out a DMM and set up a few LEDs and drive them at differing current levels to see what light level you need and work from there. I have found using various lanterns I have and flashlights that there are two levels you need for lighting, one with adjusted night vision to navigate easily, the other to be able to see people and do things that don't require extensive reading light.

I recently had a 4LED module out of a cheap light hooked up to various used batteries with a variable resistor and found that a level of light from 2-10ma was good for navigating and about 20-80 for other things. The lower current level you use the longer runtime but remember unless you put regulation or an adjustable resistor the light may start out at just the right level and in time be too dim as batteries deplete.