One somewhat forgotten aspect of flashlights is their reliability. Rightly or wrongly, Maglites were considered to be indestructible way back when, which I’m sure contributed to their sales.
But how about now? Sure, LEDs are less fragile than bulbs, but the flashlights are a little computers now, full of finicky electronics, firmwares, and what not.
I wonder what makes a light more reliable than some other light. Price (unlikely)? Simple FET driver? Mechanical switch? Potting (I’m not sure what it is)? Magic? Brand-name? Something totally different?
What’s people experience with the rate and the mode of failure of their flashlights?
My 2 years old Fenix E28 has developed a battery draining problem. It would drain a fully charged 3400mAh cell down to 50% in just a week. Since I’ve opened the bezel and replaced the emitter, it is considered out of warranty and become useless. So much as good brand. All my other cheap flashlights, including the $10 boruit D10 headlamp, hasn’t suffered battery draining problem.
I’d say besides construction, most electronics reliability is a luck of draw. If you want really, really reliable flashlight, do it without a driver. Battery → Switch → Resistor → LED. Couldn’t be simpler and will be the most reliable light you can have.
Properly designed electronics. Without cutting corners, relying on stuff like cell internal resistance to not blow up, etc. Following datasheet specs, including not overdriving emitters. FET drivers definitely do not qualify.
Potting. It is commonly done with electronics in stuff like power tools, helps flashlights too.
Proper mechanical design and manufacturing, so that there are no physical issues like bad contact etc.
Simple enough software which can not be messed up by user actions. Anduril does not qualify.
That said… what makes other electronics more or less reliable? Like phones? Price plays a role here - expensive is not guaranteed to be reliable, but cheap is less likely to be reliable than expensive…
Stupid question time; how heat efficient is potting in epoxy?
I mean, in my mind that epoxy is an insulator, and anything getting hot in it will just bake itself faster? Or, is this done encapsulating everything except the major contact points the the host/shell/whatever, so it still gets heat transfer?
To be honest if it wouldn’t kill any thermal needs I’d want to fill the suckers with a rubber or silicone… shock absorbers for a flashlight (I have a high end armored laptop buit that way, its all cased in rubber inside a bomb proof shell).
Yeah, simplicity is the only way to ensure absolute reliability. Along with good build quality and high quality of electronic components. Lots of cheap plastic 5mm LED flashlights outlast fancy expensive brand-name lights, which makes a good case for simplicity.
Ironically the first “good” flashlight that has ever failed on me was a LED maglite…
More over, all modern drivers with mode memory will suffer from flashrom write exhaustion. I wonder if good firmware, like Andruil have code path to deal with mode memory read / write failure? If not then the driver will eventually brick itself. Above posts of pure resistor / 7135 will not have flashrom corruption / write exhaustion problem ever.
Components mostly get rid of the heat through the PCB and from that into the host. Those contact points obviously have to be left uncovered, if nothing else because they are used as electrical connection too.
But also - air is great insulator and potting compound can be made thermally conductive to increase thermal mass and improve heat dissipation. Such compound is often used in usb power supplies, for example, which struggle with heat because of constant attempts to make them smaller and more powerful.
I find the biggest failure route these days is the switch.
I have one that came DOA and one failing right now that i don’t know what part number to replace it with (Romisen RC G2).
