Flashlights

We live in a forest, and we have dogs. We need to take the dogs for walks every night. We’re pretty comfortable walking in darkness but there are plenty of times we use a flashlight (often a headlamp, as that’s my preference). Beyond dog walking, if you live in a place where it regularly gets profoundly dark, you’re going to need flashlights.

So we’ve had a long series of flashlights over the past 20 years, ranging from quite tiny keychain lights to honkin’ big 3 D cell Maglite style monsters. Over that 20 years, the technology has moved from halogen bulbs being the gold standard to LED being the gold standard, and away from non-rechargeable batteries in the standard sizes (AAA, AA, C, D) to a wide variety of rechargeable batteries using a wide variety of battery chemistries (NiCd, NiMH, LiON, LiPO, LiFePO4, etc.) This has meant that the demand on the batteries has diminished at the same time that battery energy density and capacity have made rapid progress. The result is that the peerie light that I carry in my pocket 24/7/365 throws considerably more light than the massive 3 D cell powered baseball bat Maglite we started with back in the early 2000’s (60 lumens versus 45, for 7 hours versus 10 hours for the honking big Maglite).

Indeed, the progress in the world of flashlights has been so rapid and dramatic that I now consider every flashlight I buy to be a consumable item. By the time it starts acting dodgy, it will be time to replace it just because its performance is so low compared to current offerings I’d be considering replacing it anyway.

This does not mean that the world of flashlight purchasing is all sweetness and light.

In particular, flashlight development is seemingly driven by two factors:

• maximum output, reported in lumens
• maximum runtime for the lowest level of output

Beyond the problems introduced by those two metrics driving design, the list of vexing flashlight ‘features’ seems endless:

• “SOS” mode - although I can see how this feature would be useful if you were stranded in a vast expanse of wilderness over which aerial searchers were for some reason searching at night, for almost exactly 100% of the users of flashlights, this mode is useless baggage that complicates the user interface.
• Strobe mode - intended to disorient assailants, such things are useless for the intended purpose (because they’re so hard to trigger, requiring clicking through multiple modes) and are thus useless baggage that complicates the user interface.
• “Turbo” modes that put out a staggeringly bright beam (e.g. 1100 lumens or more) which can be sustained only for a very brief time (in some cases less than a minute) before the light must throttle back the output to avoid thermal damage. (for comparison, a car headlight puts out ~1000 lumens)
• “Moonlight” modes that put out a beam that is unusably weak for any meaningful use case, said mode existing solely to allow the manufacturer to make runtime claims like “up to 25 days runtime”.

Some observations:

How much light output you actually need depends on your situation and task. Some examples:

• in a normally lighted room, find a dropped object that may have rolled under some piece of furniture.
• in an unlighted room, read a book.
• in the dark, navigate briefly over even, familiar terrain.
• in the dark, navigate over unfamiliar, uneven terrain for many hours.
• in the dark, navigate over unfamiliar, uneven terrain for many hours while trying to go as fast as possible.
• do fine detail work on something that is placed such that it’s dark inside the surrounding container.
• be found by someone searching for you.

All of those will have different illumination needs, so it’s good to have some idea of what situations you expect a flashlight to be used, as that informs most of the tradeoffs.

In general you want to know:

• how much light do you need?
• how big an area do you need lighted?
• do you want an even light across that lighted field, or do you want a central bright beam surrounded by a somewhat dimmer peripheral field?
• how long do you need this illumination to last?