Flashlight! Flashlight! Who’s got the flashlight? by Jeffrey Yago, P.E., CEM

If the standard procedure for turning on your flashlight includes pounding 10 times on a table top, removing, then reinserting the same old batteries, and finally staring blankly into the unlit bulb, then perhaps it's time to rethink how well you are prepared for the next power outage or emergency.

Articles hitting the newsstands after the current rash of wild fires, hurricanes, and power outages are encouraging everyone to have an emergency pack, since outside help or evacuation may not be possible for several days. Many of my past articles have addressed emergency preparedness in great detail, and you may find it helpful to dig out some of the back issues.

All of these articles suggest that your emergency preparedness supplies include a battery-powered flashlight and extra batteries. However, there are hundreds of different flashlight types, using all sizes of batteries. Some have incandescent bulbs, some have krypton bulbs, some have LED lamps, and some have fluorescent tubes. In addition, there are flashlights designed to operate on 6-volt lantern batteries, multiple AAA, AA, C, or D cell batteries, plug-in rechargeable batteries, and mechanical motion recharging devices.

Flashlight testing

Ever wonder just how long a flashlight will operate on a set of batteries? Under normal circumstances almost any flashlight will last long enough for a given task. If the batteries are dead, you can head to the corner store to buy more. But during a real emergency, it is possible that not only your neighbors, but also everyone in your entire city or state may be without power. Your flashlights may be your only source of emergency lighting for a week or more. Even if you can find a store that is open, I assure you the flashlights and batteries were sold out days ago.

No, shopping for real emergency battery-powered lighting does not involve looking in the discount bins for one of those $3 plastic flashlights with a slide switch. You need at least two real emergency flashlights, and expect to pay up to $20 each, plus another $20 for an extra supply of good quality batteries and a few extra bulbs. Rechargeable batteries are good for everyday use, but do not hold their charge long. This makes rechargeable batteries less effective for long-life emergency backup power, not to mention that without electricity they cannot be recharged.

I no longer buy any flashlight that uses the older style incandescent bulbs and cheap slide switch, as these never seem to work when you need them and quickly discharge their batteries. Some of the newer flashlights use a much brighter krypton bulb. These are a good choice when you need to shine a spotlight a very long distance, but they will still use up batteries faster than desirable during extended emergency conditions.

New flashlight technology

The newest generation of battery-powered flashlights use one or more light emitting diodes (LED) as the light source. Although these were fairly dim when first introduced, recent advancements have made a vast improvement in both their white color quality and brightness. Unlike all other lamps, an LED does not have a filament to burn out. It is actually a semi-conductor device like an electronic transistor, and unlike an incandescent bulb, an LED lamp has polarized positive (+) and negative (-) terminals. The theoretical life of an LED lamp is in excess of many thousands of hours of operation when used with the proper power source. In addition to long life, an LED lamp consumes battery power measured in millionths of an amp, which greatly extends how long a given set of batteries will last.

Another new type of portable battery-powered lighting is the fluorescent lantern. Due to the long tube shape of a typical fluorescent lamp, most of these battery-powered lights look like a small version of an old camping lantern, not a flashlight.

Although a battery-powered fluorescent light still uses lots of battery power to operate, they can provide really good lighting levels throughout an entire room, and are ideal to illuminate a kitchen or living room during evening meals when a flashlight would illuminate only a very limited area. I recommend having at least one battery-powered lantern to go along with any other emergency flashlights you have, and limit its use to only a few hours each evening during a power outage as they consume more power than any of the other flashlights we tested.

Unless you want to stock 10 different sizes of batteries, I suggest limiting all your battery-powered flashlights, lanterns, radios, and electronic games to just two or three basic battery sizes. This makes things much simpler when they can get complicated really fast, and limiting battery sizes allows stocking more of each. Since newer lighting and electronic technology is moving to higher voltages and smaller sizes, many of today's battery-powered devices may require three or four smaller AA or AAA batteries instead of one or two of the larger C or D size batteries typically used in older devices.

How to select a flashlight

To help demystify the process of buying a flashlight for real emergency preparedness, I recently tested five of the most popular battery-powered flashlights and lanterns currently being marketed against a standard two D cell traditional flashlight. During a lengthy power outage, you are primarily interested in finding your way around an otherwise dark house, so I have not reviewed those foot-long D cell battery-powered flashlights that can shine a spotlight a mile away. We want to illuminate a small room, not blind a deer in the next county. I would like to point out that this was a less than scientific testing process, since we are interested in the relative differences between models and not specific individual performance. Whatever flaws there were in my testing, it affected all models the same.

Since a flashlight that provides a large or very bright area of illumination may have a shorter battery life, I have included a very rough measurement of illuminated area along with light brightness. I also noted how long the particular flashlight operated on a single set of batteries. All flashlight tests started out with the same brand of good quality fresh batteries. Note that some flashlights require more batteries than other designs, which will also affect useful operating life. I am using the term "useful operating life" to mean that point at which the light output is no longer bright enough to provide an adequate lighting level, not the point when the light goes completely out.

Testing procedures

I set up my photography studio with an off-white flat background that covered an entire end wall. I took a light level meter that measures three different ranges of foot-candle illumination levels and mounted it in the center of this background. I then positioned a stand to hold each flashlight with the lens exactly six feet from the light meter and background. Although I could have achieved different readings at other distances, I felt this would be a good average of working distance. The measurements of the area being illuminated were taken in a totally dark room, with the flashlight under test being the only illumination. All of the flashlights produced a very bright center area, with a larger outer area that was much less bright. The outer areas still had adequate illumination for finding your way around a dark room, but only the primary center areas were bright enough to read or work by.

Final results

The table summarizes the tests of six flashlights and one fluorescent lantern. Although any of these would easily light your way down a dark stairwell or rural road, several models provided much better lighting quality and longer battery life. All of the incandescent flashlights produced a slightly yellow light, while all of the LED flashlights and the fluorescent lantern gave off a white light. The 1-watt "super bright" LED flashlight I tested by Dorcy was actually almost blinding, and provided the largest overall illumination area.

When reviewing the results of this testing, note the extremely long time all of the LED style flashlights lasted, compared to the incandescent. In fact, I called it quits after four days of continuous operation, as both LED flashlights were still providing enough light to find your way in a very dark room, but their light levels had dropped to a tiny fraction of their original illumination. The Garrity white LED was the overall winner in operating hours, and did this with only three tiny AAA batteries.

All of the flashlights illuminated a very bright round circle directly in the center of focus. However, the fluorescent lantern was able to illuminate all areas of my entire 12-foot x 20-foot studio, although no areas were illuminated as brightly as a flashlight. I strongly recommend owning at least one of these fluorescent battery lanterns. I think the traditional slide switch flashlight with two C or D cell batteries is not suitable for extended power outages due to their shorter operating life and difficulty with their switches and battery connections making good electrical contact.

All of the LED style flashlights tested had an anodized aluminum housing, a sealed push button switch, and machine-threaded parts with waterproof rubber seals. I selected these six "finalists" due to their smaller size and rugged construction, and all would make a good general purpose flashlight. My hands-down favorite was the Dorcy "Metal Gear" 1-watt LED model. The Garrity LED was my second choice, which actually lasted far longer than the Dorcy LED model due to the less bright LED. Both were small with a single LED lamp, and both required three small AAA size batteries. I really like the metal belt clip on the Dorcy, but some of you may prefer the nylon pouch with belt loop that comes with the Garrity.

The 1-watt LED Dorcy "Metal Gear" model produced a very bright center area, with a large outer area that was also fairly bright. The Garrity LED model produced a large diameter center light with very little lighted area outside this circle, which gave the appearance of a brightly focused stage spotlight.

Most of the incandescent type flashlights are focused for much greater distances than the LED types, but for compact size and excellent battery life I believe your emergency flashlights should be LED design with a gasketed, moisture-resistant, metal housing. Most flashlight manufacturers are starting to add an LED model to their product line. I liked the Dorcy 1-watt LED model so much I purchased three for myself after the testing ended. Most of the flashlights in this article are available from Lowe's, Home Depot, and Wal-Mart.

Battery considerations

During an extended power outage, you may need to operate a flashlight or fluorescent lantern for up to six hours per night, for a week or more. This is much longer than most standard flashlights are intended to operate, and could consume up to 24 batteries depending on what type and size flashlight you purchase. This is still more batteries than you normally keep on hand, so you will need to change your thinking about stocking extra batteries, and be sure to check their expiration dates every few months.

Buying the best flashlight in the world is still a waste of money if you are not willing to stock lots of spare high-quality batteries to keep it operating. The more expensive alkaline batteries will last much longer than standard batteries and are well worth the cost for your emergency preparedness. I like to vacuum-pack my emergency batteries in multiples of four, for each flashlight's battery count. A flashlight requiring three batteries will need several packs of twelve batteries per pack. This way you will not need to open more sealed packs than necessary at one time, and I keep them stored with my emergency flashlights. Do not store batteries in a freezer as some people suggest, but you do need to keep them in a cool and dry location.

Again, this was a somewhat subjective test, but should still provide a good idea of what to look for. Be sure to keep in mind the area of illumination when deciding which model is right for you, and do not be surprised if you need more than one type to meet all of your emergency lighting requirements.

Jeff Yago is a licensed professional engineer and certified energy manager with more than 30 years of experience in the energy conservation field. He has extensive solar photovoltaic and emergency preparedness experience, and has authored numerous articles and texts. His website is www.dtisolar.com.

Flashlight! Flashlight!Who’s got the flashlight?

By Jeffrey Yago, P.E., CEM