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How to Choose AA and AAA Keychain LED Flashlights for EDC Use

keychain-led-flashlightsPowerful flashlights used to require multiple batteries or hard-to-find lithium batteries. LED technology has improved so much that single AA and AAA flashlights can now output over 100 lumens of light – bright enough to be considered “tactical” a few years ago.

This means that you can have an EDC (Every Day Carry) flashlight that is small enough to be carried on your keychain, yet uses readily available batteries (not CR123a) that give decent run times (battery life) unlike keychain flashlights that use button cell batteries.

Prices range from $20 to $100. Brands include Fenix, Maglite, Gerber and Leatherman (yes, the multitool manufacturers have gone into the flashlight business), Klarus, Lumintop, Zebralight, Xeno, Lighthound, Eagletac, McGizmo, Surefire, Photon, Proton, Nitecore, 4Sevens, Maratac, and many others. Some flashlights are labeled as Cree or Nichia. This is the brand name of the LED used in the flashlight, not the flashlight brand.

Single Battery versus Multi Battery Flashlights

One advantage of 1xAA and 1xAAA flashlights is that they are almost guaranteed to have voltage converters that will suck out any remaining juice from batteries, no matter how weak. This is because the battery’s 1.5 volts is too low to power an LED, so they have to have a voltage converter, unlike cheaper flashlights that use 3xAAA or 2xAA batteries to get sufficient voltage. (Some battery power is used up in the voltage converter, but on balance most people will consider this a worthwhile trade-off.)

However this does mean that you get less warning that your batteries are going to die because the flashlight will run at full brightness and then suddenly stop. It won’t slowly grow dimmer.

This doesn’t have to be a problem because it is easy to carry another battery as a spare. It’s more of an issue if you are using rechargeable NiMH batteries because fully discharging them will damage them and reduce the number of times they can be recharged. If you do want to use NiMH batteries, you’ll have to remember to change the batteries before the flashlight dims.

AA versus AAA

Whether to choose AA or AAA is mainly a question of size versus run time. Even the smallest AA flashlight barely fits comfortably on a keychain. The main advantage of AA is the longer run time, about 3 times the run time of AAA. AA flashlights are also often brighter.

AA batteries are easier to find, but not much more than AAA batteries, so availability isn’t a big differentiating factor.

You can easily find AA and AAA batteries in alkaline, rechargeable NiMH and disposable lithium.

Alkaline batteries are probably the best option for most uses. They have relatively long run times and are cheap. Their main drawback is that they can leak and ruin the flashlight if left unused for a few years. Use alkalines only if you use your flashlight regularly.

Lithiums are lighter, have longer run times and have a ten-year shelf-life, but are also more expensive. There are more suited for stockpiling for emergency use. They are light, so it’s easy to carry one or two with you as a backup.

NiMH rechargeable batteries will save you money if you use your flashlight a lot, say more than 30 minutes a day. You will have to put up with the inconvenience of recharging them, and of doing so before the flashlight dims (to avoid damaging them with a deep discharge).

There are also rechargeable 3.6 volt lithium 14500 batteries which almost the same size as AA batteries. Their voltage is more than double the voltage of AA batteries. Some AA flashlights can use 14500 batteries but the performance advantage is likely to be small. 14500 compatibility is therefore not an important feature.

Flashlight Lumens Brightness

flashlight-lumens-brightnessThe major brands will report the brightness of their flashlights measured in lumens, so the numbers below aren’t just some theoretical numbers. You can use them to compare different flashlights. A flashlight without a lumens rating is probably not very bright, otherwise the manufacturer would be boasting about its lumens.

Lumens brightness differences of less than 50% are difficult to see. If you look at the beam from a 80 lumens flashlight and a 120 lumens flashlight, you’re not going to see much difference. You need to have more than 100% difference in the brightness to see a significant difference.

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There’s also some controversy over lumens measurement – different manufacturers might measure them differently. So don’t worry about small differences.

There are three common brightness levels or modes for flashlights:

  1. High, about 100 lumens. Typical AA alkaline runtime is 1 hour. Depending on how wide the beam is, this is bright enough to reach out 25 to 50 yards. Which is also useful for temporarily blinding 4-legged or 2-legged predators. Good for lighting up your path in the countryside or along a dimly-lit city street. Also good for searching your backyard for prowlers. Too bright for close-up work such as reading.
  2. Medium, about 20 to 40 lumens. Typical AA alkaline runtime is a few hours. Still bright enough to light up your path, but with longer runtime – good for long walks. Almost dim enough for close-up work but a lower setting would be better.
  3. Low, less than 10 lumens. Typical AA alkaline runtime is tens of hours. Good for reading a book at night without blinding yourself, or rummaging around in the dark without waking other people up. Brightness of less than 1 or 2 lumens is sometimes called low low or “moonlight” mode. The idea is to have a setting that is so low that it doesn’t destroy your night vision.

Older flashlights usually had only one brightness setting. Newer flashlights have two or three. If there are two levels, they will be High and Medium, or High and Low.

More levels aren’t always better. While they give you more flexibility, they also make the flashlight more difficult to use. Many people just want a simple on/off flashlight and don’t want to remember some strange control sequence to change the brightness.

If you’re looking for a flashlight for personal security only, you don’t need medium and low settings.

Controls, Modes and User Interfaces

flashlight-controlsFlashlight controls are unfortunately more complicated than they need to be. Ideally you’d have something like an electric fan’s control dial where you turn the dial to set different modes. Unfortunately this often isn’t the case. The situation is so bad that the controls can and should affect your choice of flashlight.

Basic modes are: off, low bright, medium bright, high bright.

More advanced modes include: strobe (slow for beacon signaling, fast to disorientate attackers), SOS (flashlight will signal SOS in morse code).

Luckily, single AA and AAA flashlight usually have fewer modes and simpler controls than larger flashlights.

The two main controls are a click switch at the tail end of the flashlight, and a twist head near the LED. Most flashlights use one or the other, others use both.

The click switch is easy to use with one hand, and people can find it without being told how to use the flashlight. Disadvantages are that it makes the flashlight longer (not good for a keychain flashlight), and it makes tail-standing the flashlight more difficult (tail-standing is explained later in this article).

Some click switches are “3-position” with a momentary-on as the third position – a half press doesn’t engage the click but does switch on. Releasing the switch immediately switches off. This is for morse code signaling and “tactical” use (brief illumination without giving your position away).

While a single click switch looks like it has only on/off modes, multiple modes can be supported by clicking multiple times – click once for mode 1, click twice for mode 2, click 3 times for mode 3, etc. You need to click quickly, within 1 or 2 seconds. If you wait too long, the next click will switch the flashlight off.

The problem with this is that if you want mode 5, you’ll need to click 5 times. Not only is this slow, the flashlight will cycle through the other modes, possibly including high brightness, which you might not want in that situation even for a second. And that’s assuming that you remember that mode 5 is the one that you want.

So the sequence of the modes is important. Let’s say the flashlight has 3 modes – low, medium, bright. You would expect mode 1 to be low, mode 2 to be medium and mode 3 to be bright. However some manufacturers think that medium is used the most, so they set mode 1 as medium. Not only is this confusing, you could destroy your night vision with mode 1 medium, when you were trying for mode 2 low.

Another wrinkle is mode memory. Let’s say you click to mode 3, then you wait and then click again to switch the flashlight off. Now you click again to switch the flashlight on. What mode should the flashlight be in? Some flashlights reset to mode 1. Other flashlights remember your last mode and switch on at mode 3. This could be convenient, but also confusing if you last used the flashlight a week ago. For most people, no mode memory is better.

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But it gets even crazier than this. Some flashlights switch modes using double clicks or click-and-hold. That’s right, two fast clicks gives you one mode, two slow clicks gives you another mode, one click followed by a long pause followed by a click will switch the flashlight off, click and hold for a few seconds gives you yet another mode. Stay away from flashlights like this.

Now let’s look at the twist head control.

The most common twist head control is a simple on/off switch. It’s like the tail click switch, only you twist the head loose less than a quarter turn, then twist it tight again, instead of clicking. Best done with two hands though one-handed is possible. It’s quieter than a click switch. Some twist heads are positional – turning a different amount sets a different mode. This makes changing modes quicker, but you need to remember how much to turn.

Some flashlights combine a tail clicker for on/off control, and a positional twist head for changing modes. This allows you to switch the flaslight on to a specific mode, without having to cycle through other modes. However, with two controls, this does make it harder to remember how to operate the flashlight.

One last thing to look out for is the standby drain current. Some flashlights use an electronic switch that draws a small electrical current even when off. Depending on the switch, this can drain a battery in months or years. This is not a problem if you use the flashlight regularly since you’ll be changing the battery every few weeks anyway.

It’s more of a concern if you plan to store the flashlight away for emergency use. In such cases, remove the battery before storage, or partially unscrew the head or tail to “lockout” the flashlight and disengage the battery (check the flashlight manual for details).

Beam Quality

beam-qualityThe shape of the flashlight’s beam will affect its suitability for a particular task. A narrow beam is called “spot” and a wide beam is called “flood.”

A spot beam enables the flashlight to reach further, good for searching for prowlers in your back yard. Most flashlights have a spot beam, with the beam being about 5 to 10 degrees wide. A 5 degree beam will create a spot 1 foot high at a distance of ten feet, 2 feet at 20 feet, 3 feet at 30 feet, etc.

Some flashlights have a flood beam – they don’t have a reflector and act more like a lantern, throwing out a beam that is 90 degrees or wider. They are useful for indoor and close-up use but don’t have enough reach to be used outdoors. One advantage is that without a reflector, they are shorter than other flashlights.

A zoom head allows you to switch between spot and flood. It does make the flashlight bigger and adjusting the zoom can be a pain. Unless you have specific requirements, a fixed spot beam is best.

Even for a spot beam, some light will still flood out to the side. This is called the spill. It is useful because it does give you some short range side illumination, while still concentrating most of the brightness in the spot for long range illumination. Different flashlights will have spot/spill patterns of different sizes and brightness ratios. For most uses, the pattern doesn’t matter much.

The spot and spill should show even illumination with no hotspots or dark areas. Old incandescent flashlights (especially the zooms) were notorious for having doughnut-shaped spots, with a dark center. Present day LED flashlights are better and most will have a uniform spot and spill, but it’s still good to check.

To get even illumination, either faceted or “orange peel” (dimpled) reflectors are used. They slightly smear out the beam, causing any hotspots to smoothen out. However it’s still best to look at the beam and not just the reflector – smooth beams are possible without an orange peel reflector.

You can search YouTube for videos of “beam shots” of specific flashlights, showing spot, spill and beam consistency.

Another thing to consider is the color or tint of the light. Flashlight LEDs are naturally blue. A luminous phosphor is painted over the LED to convert the blue light to white or light yellow. Most people prefer a slightly yellow light, but this means a dimmer beam. For most uses, the color of the beam isn’t important.

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Some flashlights flicker at medium and low settings because the flashlight uses PWM (pulse width modulation) to dim the LED by switching it on and off very quickly – maybe 50 to 100 times a second. Some people are sensitive to flicker and are disturbed by this. A higher PWM frequency of a few thousand hertz, or a current-controlled circuit will avoid this problem. To find out the PWM frequency, search the internet for the flashlight’s model number and “PWM.”

Lastly, the LED should be centered, meaning that the beam should shoot out straight from the flashlight without skewing to the side. A few degrees off is acceptable but more can be annoying though still usable. How centered the LED is depends on the factory’s quality control, and can vary from sample to sample even for the same flashlight model. The big name brands are usually better at centering their LEDs.

To check LED centering, switch on the flashlight, roll it on a table and watch how the beam moves – it should trace out a flat horizontal line on the wall. An uncentered LED will cause the spot to bounce up and down.

Attachment Method

For keychain use, all you need is to be able to fix a lanyard or keyring to the flashlight. Some flashlights have a lanyard hole, others have a pocket clip. You can fix a lanyard to almost anything, including a pocket clip. If there is nothing, you can fasten a nylon zip tie around the flashlight.

A reversible pocket clip enables you to clip the flashlight to the brim of your hat, like a headlamp, for hands-free use. (If not reversed, the flashlight would point back at you.) Pocket clips that are screwed on to the flashlight are more secure but harder to reverse. Pocket clips that are only held on by a spring, are easier to reverse but often work lose over time.

Other Features

Brightness, controls and beam quality will make or break a flashlight. Less critical but still worth considering, are features such as:

  • Waterproofing. Many flashlights are waterproofed to one of the IPX or other standards, for example IPX8. You’ll just need a flashlight that works in the rain, so the actual standard doesn’t matter (IPX8 involves submerging the flashlight in 2 meters of water).
  • Tail-stand capability. Flashlights with a flat tail end can be stood up on their tail, shining their beam straight up so that it reflects off the ceiling, lighting up the whole room. This provides soft, even, non-glaring light which is useful in a blackout situation where your house lights are not working. However single-battery flashlights are quite small and are unlikely to tail-stand easily. Flashlights with tail click switches are also less likely to tail-stand properly (they can, depending on the design – the switch needs to be recessed). Instead of tail-standing, you can put the flashlight in a cup.
  • Glass lens. A glass lens is less easily scratched compared to a plastic lens. This is important if you throw your flashlight into your pocket where it can get scratched up by your keys. A plastic lens can get scratched so badly that the flashlight’s beam is affected.
  • Recessed lens. A bezel on the head will give some protection to the lens from scratches.
  • Strike bezel on the head. A strike bezel looks like a crown. The points of the crown concentrate force, allowing you to cause more injury if you need to hit an attacker with the flashlight. This is more for larger flashlights where you can get a good hold on the flashlight. It’s less useful on single-battery flashlights.
  • Anti-roll. Most flashlights are round, making them roll easily on flat and sloped surfaces such as the hood of your car or an uneven table. A pocket clip will be enough to stop the flashlight from rolling. Some flashlights have an octagonal head for this purpose.
  • Magnet. This is a rare feature, useful if you want to keep a flashlight handy on your refrigerator door, or if you need to temporarily fix the flashlight to your car body. The magnet will also stick to your keys, so it doesn’t work so well on a keychain.


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