The ability to make light anytime it’s needed should not be under estimated. In a dark parking lot, under your desk looking for a wall jack plate so you can get ethernet access from your corporation (true story) or walking your dog, having a quick and reliable source of light is always helpful.
Like all “Every Day Carry” items size and capabilities need to be balanced. What you can get in a single cell flashlight is really amazing, it was long ago (20 years ago) that Surefire introduced its first double CR123 flashlight with an incandescent lightbulb that produced 60 lumens for 1 hour, and 10 years ago they introduced their first LED option that produced 80 lumens for 2 hours. Now a days, getting 300+ lumens out of a single cell with an hour of run time is easyand many lights present multiple levels of light output. The technology continues to improve at an impressive rate, in terms of light out the front end and in run time allowing more total lumens to be squeezed out of the battery power available.
Just like we often decide what cartridge we want a firearm to fire, before we think about what gun to purchas like do I want a 380, 9mm or .22LR, we need to think about the battery before we think about the flashlight. The first question is rechargeable verse disposable, lithum-ion non-rechargeabe batteries have a very long shelf live (10 years), so if it’s going to not be used often, this makes sense. Most lights that offer multiple illumination levels have smart switches in them that have some parasitic drain, so if you need a long shelf live you will need to prevent the battery from completing the circuit either by loosening the cap, or placing a plastic disk inline with the batteries. The next big question is what size battery should your light run on? I think for EDC that a single cell light is the most likely to be daily carried, which leaves us with CR123A or AA sized. Triple As just do not have enough energy contained within its skinny frame for a primary light, and 18650 (size of 2 stacked CR123As) is for me a little too large, if you can carry it than great, but it really is the fully size all steel 1911 of the flashlight family.
Let’s talk about the AA formated battery. Rechargeable AAs are normally 1.2 volts where disposable are 1.5 volts. There is also a rechargeable 14500 which is 3.6 volt but is physically the same size. Many flashlights will run with either the 1.2/1.5v or 3.6v cells, often being brighter with the additional voltage. The great thing about a AA light is the possibility of finding batteries forsale, if you ever need a replacement, do to their ubiquitous nature. The CR123A battery also come in 3 flavors, there are the disposable ones at 3 volts, and there is RCR123A that are a rechargeable 3 volt option, lastly there is a 16340 which is the same size but at a higher voltage of 3.6-4.2 volts. As with the double A models some lights are brighter with the higher voltage. The downside with CR123As are that if you run into a store to pick them up they are more scarce and very expensive. If you plan ahead you can get a quality cell (Surefire) online for about $2 online or of course you can use rechargeable.
You should think about what type of switch you want. There are side and tail switches as well as twisting. Tail switches are good with the syringe technique used while holding a handgun, but prevent tail standing which can be used to light up an area hands free. Side switches are another option they allow for the possibility of tail standing, but could run a risk of activation in your pocket. Both provide good UIs (User Interface) in terms of selecting modes and brightness levels, but you have to remember how many clicks to get to what mode, but often they remember your last setting and make it easy to return to that setting. Lastly, is the humble twist switch, which never has memory (nor does it have any drain) is difficult to use one-handed, but are often the shortest and most simple to operate (and often slightly cheaper due to the simpler construction).
Some other random things to think about are beam pattern, do you want it to have more of a spot light effect or more of a flood pattern? There are is the color of the light, which can be more natural (yellowish) or a cold white light which is often a better “thrower”, but do not reveal their true color of itmes under its beam. You have to think about how you are going to carry it, will it need a pocket clip, lanyard or key ring?
There is a Navy Seal saying, “that 2 is one and one is none”. Remember there is a light on your cellphone can normally serve in a pinch, so one quality light is all you need (even though a small key chain light like the Nitecore Tube (picture inline) for less than $9 would be a great lite light with a great UI and 45 lumens on tap or the lilliputian Fenix UC-02 with build in recharger and 130 lumens for 25 minutes in something about 2/3 the size of a AAA battery.
You want to buy a quality product, but that does not mean you need to spend a ton of money. Stick with a major brand like Zebralight, Olight or Fenix and you would be hard pressed to go wrong. The Fenix E15 (2016 model) is $30 and the Olight S1 can be found for $40 if you look around. The On the Road M3 can be had for about $21, and could be a great budget entry into the EDC flashlight world.
I chose the Zebralight SC52w which creates 480 Lumens until is lowers it’s output because of thermal protection, has a real screwed on clip which I wanted for pocket cary and a great UI. It can take standard AA batteries if needs though I normally run it off of 14500s. There is a Zebralight SC32 which is very similar but takes CR123As could also be a great choice.
There are “flashlight nerds” and they tend to hang out at budgetlightforum.com or the candlepowerforums which is a great source of reviews and information. Last thing to remember is Chinese manufacturers sometimes lie 🙂 The On the Road M3 happens to have worked pretty well for me, and has some great features copied from Olight like a magnetic back-end, but it’s lumen rating might be a little generous as compared to other lights with similar ratings (but it’s still impressively bright). Exaggeration happens with batteries as well, both AA and CR123A batteries have about 850MAH @ 3.6 volts of energy maximum, which is approximately 2550mah @ 1.2 volt as found in the newer eneloops, anything higher than this currently not possible and remember some vendors lie.