If the power goes out for any extended period of time, emergency lighting will become very important. While LEDs are sexy they have limitations. Most people are not aware that they are not any where near as efficient as many people hawking them portray. Of the total amount of light produced per watt a DC input compact flourescent (CFL) delivers much more light and at less cost.
LEDs are great for focused light applications (flashlights and reading lights) low level illumination, red night vision lights, and for use in places where you don’t want the light source failing or where it is very hard to change the bulb. CFLs are better when you need a lot of light over a broad area (e.g. typically room lighting such as the kitchen or living room). Both types should be part of your preps.
Here is some info and a few of the better links on lights, including comparative info on various LEDs and flashlights, applicable for emergency and off-grid applications that I have found:
Efficacy and efficiency
A light can waste power by emitting too much light outside of the visible spectrum. Only visible light is useful for illumination, and some wavelengths are perceived as brighter than others. Taking this into account, luminous efficacy is a ratio of the useful power emitted to the total power and is measured in lumens per watt (lm/W). The maximum efficacy possible is 683 lm/W. Luminous efficiency is luminous efficacy divided by this maximum and so is expressed as a number between 0 and 1 or as a percentage. However, the term luminous efficiency is often used for both quantities.
When choosing lights for living applications, the Color Rendetion Index (CRI) is important. This is a comparative number to natural sunlight, where CRI = 100. Anything over 80 is usually OK, over 85 is good and anything over 90 is very good. You will need a full spectrum light to get to around 95.
Another thing worth noting is that regular flourescent lights operating off the 60Hz coming out of the wall usually have a 60Hz flicker that is generally only subconsciously noted. However, it does give some people eye strain and/or headaches. The flicker may be greater when powering the light off some non-sine wave inverters. Most of the new compact flourescent lights (the ones with a regular Edison screw-in, bulb base) and ALL the 12 or 24 VDC input ones use high frequency switching and there is no flicker.
Basically if you want a flashlight you want high lumens over a narrow angle for a long throw distance (or to be bright enough to blind an intruder). Some flashlight have focusing rings on the head for adjusting the throw angle from broad to narrow. LEDs are ideal for flashlights and will make the batteries last much longer than using incandescent bulbs. In general a low cost one is not good for much than what any cheap flashlight is good for other than longer operationon the smae batteries. See the links below for some comparisions. If you are lighting a living space and want a lot of light use CFLs and get the most lumens per watt for the same wattage. A reading light/lamp is in between.
The efficiency and lumens per watt of common lighting sources are as follows:
candle 0.04% / 0.3 (Efficiency% / lumen per W)
Incandescent 40 W tungsten 1.9% / 12.6 60 W tungsten 2.1% / 14.5 100 W tungsten 2.6% / 17.5 glass halogen 2.3% / 16 quartz halogen 3.5% / 24 tungsten-halogen 2.6% - 3.6% / 18–25 high-temperature incandescent 5.14% / 35
Fluorescent 13 W twin-tube fluorescent 8.2% / 56.3 compact fluorescent 6.6%−8.8% / 45–60
Light-emitting diode white (low power) 2.2%−6.2% / 15–42 . white (high power) 3.8%−8.8% / 26–60 white (prototypes) 8.8%−14.7% / 60–100
Arc lamp xenon arc lamp 4.4%−22% / 30–150 mercury-xenon arc lamp 7.3%−8% 50–55
Ideal radiators deal black-body radiator at 4000 K 7% / 47.5 ideal black-body radiator at 7000 K 14% / 95 ideal white light source 36% / 242.5 monochromatic 556 nm source 100% / 680
While the chart makes it look like a high efficiency LED provides about as much light as a CFL you need to understand how light is measured. If a light source emits one candela of luminous intensity into a solid angle of one steradian ( http://en.wikipedia.org/wiki/Steradian) the total luminous flux emitted into that solid angle is one lumen. There are about 12.6 steradians in a sphere. If the light source emitted uniformly in all directions it thus provides 12.6 times more light than a source that illuminates over one steradian. The light from an LED is very directional only illuminating over one to a few steradians while a CFL is nearly omni-directional illuminating most.
The directional nature of LEDs is the reason why an LED replacement for many incadescent bulbs have many LEDs pointing out in all directions and why lots of LEDs pointing in the same direction (e.g. a LED traffic light) is so bright.
LIGHTING LINKS (you should find something that lights your interest)
Don Klipstein’s Lighting Info Site! http://members.misty.com/don/index.html
http://www.otherpower.com/otherpower_lighting.html
http://www.efficientlighting.net/
NLPIP – Lighting Research Center http://www.lrc.rpi.edu/programs/nlpip/index.asp
National Lighting Product Information – Screwbase CFL Products http://www.lrc.rpi.edu/programs/NLPIP/PDF/VIEW/SR_SB_CFL.pdf
Compact Fluorescent Light Bulb Investment Analysis Worksheet http://www.homepower.com/files/kerrcflbulbs.xls
http://www.sylvania.com/LearnLighting/LightAndColor/UnderstandingLight/
Luminance Converter http://www.onlineconversion.com/illuminance.htm
LEDs & LED Lights http://www.enluxled.com/ http://www.lumiled.com/led-lamps.htm http://members.misty.com/don/led.html http://lighting.sandia.gov/Xlightingnewsarchive.htm http://members.misty.com/don/ledx.html http://ledmuseum.home.att.net/ (the definitive source for LED info)
12VDC Fluorescent lights and LED lights http://www.backwoodssolar.com/Catalogpages2/lights2.htm
12VDC Fluorescent lights http://www.thinlite.com/products.htm http://www.fluwikie2.com/pmwiki.php?n=Forum.12VDCCompactFluorescentLightBulb
12V ballasts http://www.thesustainablevillage.com/servlet/display/products/byCat/7/29/84/
Full Spectrum Lights http://www.lightforhealth.com/ http://www.fullspectrumsolutions.com/ http://www.fullspectrumsolutions.com/ultralux_high_definition_31_ctg.htm http://www.soluxtli.com/ http://www.aerolights.com/energysaving.asp
Dimming Fluorescent http://www.lutron.com/ballast/whylutron.asp http://tinyurl.com/pcuss
Flashlights http://www.candlepowerforums.com/vb/ http://www.flashlightreviews.com/reviews_index/reviews_index_selfpower.htm http://www.generationgear.com/products/shakelight_comparison.html http://ledmuseum.home.att.net/ledleft.htm http://www.elektrolumens.com/ (VERY BRIGHT flashlights!) http://www.equippedtosurvive.com/led_lights.htm http://www.flashlightmuseum.com/ http://www.flashlightreviews.com/index1.html http://www.shake-flashlights.com/
Lanterns http://www.flashlightreviews.com/reviews/riverrock_lantern.htm
Bulbs http://freespace.virgin.net/tom.baldwin/bulbguide.html http://www.coffj.com/veg1/lamp.htm http://www.pti-nj.com/obb_lamps.html
This is a huge amount of information. Thanks!
Holy Moly Pfwag! Just tell me what to buy, provide a link, and I’m on my way. I can’t do it all yanno. Today I ground wheat for the first time, baked the bread, and ate it all. the family only got small slices (cause they didn’t help much) sound familar? Wasn’t that the little red hen? Please don’t make me become a lighting expert too!
Good grief! Decided to take the plunge and the first flashlight I checked out was $150.
lohrework, I started investigating water and ended up writing a water report. 115 pages later(almost finished) I now know more than I ever wanted to know about water. With PBF there are so many things that we all need to learn. I wish there was a “flupedia” around somewhere (?) that we could all post to when we do find good and cost effective solutions to various things. Water I can tell you about. Lighting I am still learning.
Since water is more important than lighting the above is just the results of a maybe 10–15 hours of research whereas I have over 700 on water. In any case, I am getting the 12VDC florescents for large area lighting because it is the simplest and most cost effective way to have a lot of light. I bought and tested some and posted the results on another FW thread http://tinyurl.com/onho7
For flashlights there are reasonable solutions that will cost you a lot less than $150. Basically for these, unless you are looking for a high end model that is bright enough to blind an intruder, you just want something that has an LED bulb and uses the right size batteries that you either have lots of or can recharge. The batteries are the key. If you have the ability to recharge batteries go that route. If not, lithium batteries have the longest shelf life (all batteries self-discharge sitting on the shelf unused). IDEALLY, you would want maybe two different size batteries for all your portable electronics. Maybe AA and D but Murphy’s Law says that you will have something that needs different batteries.
I will eventually be coming up with specific recommendations. I will post them at www.arielco.us where I am (slowly) putting up the results of my other studies and endeavors.
PS: I still have a Famiy Grain Mill, Whisper Quiet electric mill, Zojirushi breadmaker, solar oven, and 200lbs of nitrogen packed, organic, red winter wheat all stored away from pre-Y2k days. At the time, all were the “best” at what they did. I did all the research, learned what was best and procured everything but then the little red hens in my family wanted me to make the bread too with the end result being that all that good stuff has never been used. Fortunately I didn’t dump it on E-Bay.
I just bought a retrofited 32 LED bulb for my Maglight flashlight — supposed to be really bright, but I haven’t received it yet.
I’m also looking at 80 LED spots for outside as well as some solar (2000 lumens) but I haven’t compared to see if 2000 lumens is actually any good yet. :-)
I’m glad to get this info & will pour over it this week to see what I can learn, thanks for all the time it took to get this together!
BUMPTY BUMP - this is a great thread and it shouldn’t get lost
bump
(-and what about Lighting Safety for those unprepared who will suddenly use candles, unfamiliar fuel lanterns, ect, if they are caught in a power outtage? Communities should be getting safety info to households because, they’d be so “on their own” if they got into trouble in a pandemic. )
I know I sound like an old drag … but if the majority of the world is going to be without lights then the actual schedule of the world is going to change.
That means that significant amount of light after dark may not be as necessary as they are in our current society. You will go to bed when it gets dark and you will get up when it gets light. You will do as much of your work as you can during that time period.
If the power grid goes down, the fuel grid probably will as well … so no traveling after nightfall either in my opinion because there won’t be lights to travel by.
I’ve got minimal light needs … some lantern fuel, some coleman fuel, some flashlights (battery operated and rechargeable), and some candles. It would be a waste in our home to try and get too fancy. When we go camping we adjust very quickly to the change in environment as far as lightness/darkness goes. We’ve been through some hurricane-related power outages that show that the same thing happens.
There simply will be no reason for us to over extend ourselves trying to work in the dark.
Kathy - this is a typical December day in CT (from the US Navy) Sun and Moon Data for One Day The following information is provided for New Haven, New Haven County, Connecticut (longitude W72.9, latitude N41.3):
Sunday
10 December 2006 Eastern Standard Time
SUN
Begin civil twilight 6:35 a.m.
Sunrise 7:07 a.m.
Sun transit 11:45 a.m.
Sunset 4:22 p.m.
End civil twilight 4:54 p.m.
While I totally agree that your body would adjust/you’d re-adjust your schedule, etc., ain’t no way my kids are going to bed at 5:00 at night and sleeping until 7:00am the next morning! We have to be able to go out in the dark and get firewood, etc. And it’s emotionally difficult to tell a child who is afraid of the dark that “no you can’t have a flashlight on in your room. we have to save on batteries.” For me personally, lighting is an issue. Being cold in CT in the winter would be bad enough, but totally dark as well would be mentally challenging.
There simply will be no reason for us to over extend ourselves trying to work in the dark. Caring for the ill?
Headlamps are very, very efficient, hands free lighting. Most backpacking/mountaineering headlamps are dual LED (efficient general work lighting) and xenon 100+ foot long range projection beams that work on 2–4 AA or AAA batteries. Stock up on top quality (Maha) AA rechargables and your good to go. Also the LED “lanterns” that go 40+ hours on 4 D batteries are great.
Pfwag - A great posting! You have certainly covered a bunch of the material that I hesitated to put up here, and you did a marvelous job with it.
Laura B.: “And it’s emotionally difficult to tell a child who is afraid of the dark that “no you can’t have a flashlight on in your room. we have to save on batteries.” For me personally, lighting is an issue. Being cold in CT in the winter would be bad enough, but totally dark as well would be mentally challenging.”
Probably your family will be sleeping in a big pile together just to keep warm, so flashlights at night wouldn’t be an issue, except for using the toilet.
LauraB - You should probably look into either wind-up lights to help keep the kiddos company, or else look into Krill Lights. They run on a couple of AA batteries for a LONG time, and if you get a solar charger and rechargeable AA batteries, you should have low level lighting to chase away night panics for almost indefinitely.
Link: http://tinyurl.com/gpso2
This is one of the first areas I addressed when I started prepping and I’m still adding to it. I’ve got a avriety of candles, kerosene lanterns, crank flashlights, rechargeable battery lanterns, a variety of regular flashlights, regular and rechargeable batteries for them, and a solar battery charger and another charger that can use either AC or DC. I’m not bragging, I’m just stating how important it is to me to be able to see after the sun goes down. Oh yeah, last resort are the lightsticks.
“I’m-workin’-on-it – at 22:15 I just bought a retrofited 32 LED bulb for my Maglight flashlight — supposed to be really bright, but I haven’t received it yet.
I’m also looking at 80 LED spots for outside as well as some solar (2000 lumens) but I haven’t compared to see if 2000 lumens is actually any good yet. :-)
I’m glad to get this info & will pour over it this week to see what I can learn, thanks for all the time it took to get this together!”
Have you looked into “Luxeon stars”? One of the one watt stars = 10 regular leds and they are compact and pretty cheap. I got my latest shipment for $4.33 each including tax and shipping (12 pieces). I am using most of those for Christmas gifts this year. I rewire 4 d cell flashlights and wire in one of those in each one. The spec sheet says they are rated at 100,000 hours (the life of the star, not the batteries).
http://www.lumileds.com/products/family.cfm?familyId=2
P.S.
If you wire your own leds you have to know how to calculate what size resitor to put in series with the LED to keep it from frying. Help is available. Just ask.
Thanks Eccles - a battery recharger is on my list of items to get next. Do you have any recommendations for a solar recharger? I already have some crank lights, battery lights, rechargable lights. I guess a solar light would be one other I should get?
Thanks Eccles - a battery recharger is on my list of items to get next. Do you have any recommendations for a solar recharger? I already have some crank lights, battery lights, rechargable lights. I guess a solar light would be one other I should get?
LauraB – at 12:59 and lugon – at 13:46
What I meant was that I wouldn’t extend the resources of my family to go for the big expensive lighting options like $150 flashlights. <grin> I do have lanterns, fuel, and candles. I even “splurged” on a solar battery charger.
I will admit that living in southern US affords me more daylight year round than some might have. And out west I remember being stupified that it was still dusk at 10 pm at night during the summer. It was even too light for my family to feel like going to sleep.
Each family, of course, has to do what they need to address their own special issues.
I’ve got a couple that go through periods of being afraid of the dark here in the house. But not while we are camping … go figure. And they are not afraid when it is dark outside … only the inside dark.
I think, for my kids anyway, there will be more things to be afraid of than the dark if a pandemic does occur.
To address some of that, I went to the flea market and picked up some “shaker” flashlights. They cost me a buck a piece. Each kid will get their own … no worrying about batteries or turning off lights so we don’t waste resources. Shake, turn on, and by the time it goes out, they’ll be asleep.
“Shake, turn on, and by the time it goes out, they’ll be asleep.”
Too bad they don’t make a hand-crank Glo Worm…
I have invested heavily in Hello Kitty lanterns and a butt load of batteries.
Glo little glo worm, glimmer, glimmer…I’d like one of those too HB!
Excelent flashlight, headlamp and glo thingy review site
(PFWAG, if you havn’t seen this site, I think you will love it!!! hehe)
lohrewok - here’s a link to some very low cost LED flashlights: http://tinyurl.com/lsnup I have never bought anything from them so can not vouch for thier integrity. Note the other LED flashlights on the other pages. However, none of them are high quality flashlights that you will be passing down to your kids some day. I did just buy the listed model FL307T from another source that I needed to buy some electronic parts from and that just happened to have the FL307T. I paid $4.95 and it came in today. All these flashlights are cheap, Chinese made junk and other than having LEDs as the light source are not that much different than the cheap, Chinese-made, incandescent bulb flashlights that you can buy at WalMart. However, for $2.99, batteries included, you can’t go wrong so buy one for all the kids.
The FL307T comes with a belt holder and three “super heavy duty” Ningli AAA batteries. “Heavy duty” is usually a euphemism for a carbon-zinc battery, which also cost less than an alkaline battery. The batteries go into a little removable battery holder cassette, making it very easy to intall the batteries correctly. The case is actually aluminum, and the threaded end cap has a rubber o-ring on it but I doubt the unit is water proof. Maybe if you put some clear sealant around the circumfrence of the front lens. While the unit does have nine LEDs, overall they are not real bright. In a completely darkened room, at four feet it throws about an 18 in diameter spot that is bright enough to easily read something. Shining it around the darkened lab, it is very usable. It doesn’t throw too much light very far so, outdoors, won’t be too much good except to keep you from falling into the pit latrine in the middle of the night.
I did a real quick power measurement and the LEDS draw about 350mA when first turned on but then the draw drops steadily where at about 2 minutes it was drawing about 250mA and still slowly declining. While there should be some decline I wasn’t expecting that much. Probably a result of lousy batteries.
Quickly checking standard battery capacity (http://tinyurl.com/gcrrd) I note that carbon-zinc batteries provide about 540mAH. Assuming the cheap batteries that come with the unit only provide 75% as much (lousy battery and declining capacity due to shelf life) and that the average draw will be about 200mA after a bit the FL307T will provide about 2 hours of light. Putting in some name-brand alkaline batteries would boost that to about 5 hours. Note from the battery capacity table, you don’t really want a flashlight that uses AAA batteries if you will be needing to use it a lot. Anybody have a line on a cheap, Chinese-made LED flashlight that uses AAs or Cs?
FYI: Some other good sources for battery info: http://en.wikipedia.org/wiki/Battery_(electricity) http://www.batteryuniversity.com/index.htm http://www.greenbatteries.com/index.html
Centella - you ever do any rewiring using a constant current switching regulator designed for driving LEDs?
Eccles - what is making the light in the Krill? LED or CFL?
MAV - yes I had that link, noted above. Been collecting this stuff for years.
oops-forgot to stick my handle in the author in posting above
Krill lights use neither LED’s or CFL’s… it is a phosphorescent technology, same as the technology in an IndiGlo watch. There is no bulb, no filament, just what looks like a hollow polycarbonate tube which has something on the inside of the tube that almost resembles a piece of paper.
They were invented by a former Navy SEAL. Krill lights are rugged, extremely durable, have NO expiration date (will last on a shelf without batteries indefinitely and be good to go the moment batteries are inserted), are safe to use (even for kids), and are used extensively by the military, law enforcement, and by anyone else who uses chemical light sticks but wants to save money.
I personally think that they’re one of the greatest inventions ever!
anonymous – at 19:05
Centella - you ever do any rewiring using a constant current switching regulator designed for driving LEDs?
I have a schematic for a constant current circuit but have decided not to use it because a current limiting resistor works so well. I can see the benefit of having the led not do dim with varying input voltage but I am not that picky about lighting. In regard to Voltage regulator circuits, You would need one if you where running leds directly off of a solar panel (since the voltage without a load on a 12 volt panel can exceed 17 volts. Also the voltage regulator can have the same effect as a constant current circuit in that you could run 12 volts into a 5 volt regulator and get the same intensity of light over a wide range of input voltages. I have used the LM350 series of regulators which I think is linear and not switching. They are easy to use since the input voltage goes in. The regulated output voltage goes out and the ground is common to both. A switching regulator circuit would be more efficient so see the link below. I never really thought about improving on the cheap and dirty resistor circuit since I was so pleased with one of my first flashlight I made that ran for about 400 hours on a set of batteries (not that bright though).
93% efficient circuit: http://tinyurl.com/k2onq
constant current Circuit: http://tinyurl.com/gaofu
I got 3 really neat solar lantrns that work all night. The last of the light fades just before sun up. They came with stakes to hang from and also a tree type of holder so that all three can hang together. They cost about $60 for the three of them and they are stainless steel.
centella - thanks! Got one for efficiently driving a 12V automotive LED bulb from a lower voltage?
I’m thinking that the automotive bulbs are cheap and driving one from 6v (two 3V lithium or four NiMh AA batteries in series) might make a nifty and efficient low cost light. Being able to recharge the batteries from a 12V source is key. While one could charge a 12V battery from a 12V source there are OTS battery chargers for the former.
Here’s the best/cheapest place I’ve found for batteries: http://www.cheapbatteries.com/
Note the Fuji NiMh kit with 4 batteries and both AC and 12V DC input fast charger.
pfwag – at 11:49
“Got one for efficiently driving a 12V automotive LED bulb from a lower voltage?”
I’m on break at work but will have it on friday and post it. What you need is a DC to DC converter on a chip (integrated circuit). Digikey has loads of them.
Centella - OTS DC/DCs I got tons of. Too expensive and probably too big to integrate into a flashlight. Need a small and very high efficiency circuit like the TI63000 http://focus.ti.com/lit/ds/symlink/tps63000.pdf which would make a good CV source for driving LEDs but can’t do 12V.
Spirit In The Wind - any more details ref your 3 solar lights? are they garden path solar lights?
The Costco windup flashlights are one of the best I have used (that’s not alot.) $19.95 or about $24 with a built-in am/fm radio (I bought mine without to keep them simple). Its a Durapro, but the model is not listed a Durapro’s website when I checked. Its an LED light VERY BRIGHT, does go a long distance and easy to read by, and really does go close to an hour on a one minute windup. Was much easier to use than the shaker type lights I tried. I’ve seen it nowhere else.
Fiddlerdave – at 01:25
You might want to refer to the “Solar, etc.” thread for informaion on the proper care and charging of you flashlights. Winding it one minute ain’t the way to go!
See Let’s Get Cranking at 18:20, for the condensed version, I think.
crfullmoon – at 09:11
Thanks, my error. And I was the one who started that thread. Geez, it sucks getting old.
Huh, what were we talking about?
-Oh, yeah, it sure does. (Youth is wasted on the young.)
The mother of all flashlight sites.
I purchased one of those solar out door lighting yard lights, thinking it would light the path from car to front door. It cost about $25 and is a complete weenie. I originally thought that this unit would be a good thing to have if TSHTF but it really only illuminates about a six inch circle. It would be hard to read/work/or move with it.
Olymom, me too-but not a complete waste of money. Try bringing them indoors at night, they seem to be more functional there, and they work best when elevated or hung, if you can, to cast their light downward with no obstruction. At a minimum they’ll make comforting night lights for children when brought inside at night.
pfwag – at 11:49
“Got one for efficiently driving a 12V automotive LED bulb from a lower voltage?”
Lots of dc to dc circuits
I run 24 VDC solar, and step up/down from there using direct-conversion DC or inverters for AC as necessary.
There are a lot of 24v/48v to 12volt power supplies out on the market.
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