To those yet again engaged in the rechargeable discussion:
The Aeon and Nautilus were designed around 3V cells, the standard lithium batteries available off the shelf that are used in cameras and various other electronic equipment. The rechargeable versions of these cells are not properly designed and have a far higher voltage than what they should given their intended application - this is not my fault, and not something that I can easily design around, nor do I have any interest in doing so.
The Aeon and Nautilus are equipped with a very efficient board optimized for running in boost mode off of primaries. Primary cells have a voltage of roughly 3 volts. If you get a rechargeable cell that is properly designed, as has been noted by folks here, the light works exactly as you would expect it to - the circuit doesn't care what the source of the voltage is so long as it's the right voltage.
The LEDs in my lights have a forward voltage of roughly 3.3 Volts. For a
boost converter to function, it needs to be able to do just that, boost, which means that the voltage of the battery must be somewhere beneath that. Most rechargeable cells do not do not fit this requirement because of their poor design of being allowed to be overcharged up to 4.2 volts. Chances are high that if you actually tried to put some of these cells in a camera, which is what the cell size is/was primarily used for, particularly if the camera has multiple cells in series for power, that you'd blow the internal circuit.
Now, someone could counter the point above by saying "You could use a buck-boost converter instead". Yes, I could, but there are very good reasons not to. The majority of buck-boost converter chips out there cut off regulation at somewhere within the two-point-something volt range - running off a 3 volt cell, your runtime would be significantly diminished compared to my current solution which sucks the cell nearly dry. So, while this may allow you to run badly manufactured cells in the light as well as primaries, you have some very serious drawbacks towards running in that configuration.
As for those who opt for programability of some kind, you'll have to look elsewhere for that because you won't see it from me. I like fully regulated lights, not LDO or PWM "regulation", and I like simple off-low-high continuous switching and not repeated on-off cycles in order to get a flashlight to do what I want it to do. To me, for my uses, interfaces such as the FLuPIC, lights with "tactical strobe" and all these other options built into the light are feature bloat and hinder rather than help my use of the light in any conceivable situation I'm in. Of course, you're mileage may vary in that regard, but lights that do this are outside of my design philosophy and I hope this explains a little bit as to why.
Now, to address the topic of the rechargeable cells proper. Standard rechargeable lithiums hate being overcharged. The also hate being overdischarged. They have a propensity to explode when mistreated. Unprotected cells are particularly suspect to this, and the protection circuit in protected lithiums isn't designed or intended to be a multi-use device for repeated failsafes against overdischarging, and it is not something I would comfortably rely on for safety against an exploding cell. Moreover, just because the impact on an electric bill is small to recharge a cell, there is no such thing as "free lumens". You may not be physically throwing a cell away into a landfill, but you are having some lumps of coal burned somewhere to provide the power to recharge your cell - either way something is happening that has its drawbacks, you cannot get a free lunch.
Regardless of which chemistry you try to feed to any of my lights, the converter will suck the cells down to below their safe discharge threshold. This allows for maximal runtime around the cells the light is designed to work off of. As has been noted by others here, and I'll reiterate again myself, for all the reasons above I do not recommend the use of rechargeable cells in my lights. Should you choose to use them despite this, any effects resulting from their use are entirely your own responsibility.
Every single design one chooses to make is a compromise between a wide variety of alternatives. I could make a light that does
everything you could ever conceivably want it to do, but it would not be small, and it would not be cheap. My designs are done to try to achieve a nice (in my opinion) balance of size, output, runtime, and durability. I believe that the Nautilus and Aeon both do this well, and I can say that I'm genuinely pleased with the way they perform. Will they satisfy everyone's wants or needs? Probably not. They will, however, provide a good amount of light when you need it, for a long time, in a minimally small and very durable package.
At the end of the day I suppose this post comes as a response to a theme that is somehow recurrent every few months about rechargeable batteries that never seems to be adequately addressed because it keeps coming up. :nana: Hopefully this will provide sufficient insight as to the hows and the whys about the operation of these lights to at last settle the discussion.
And finally, I sought to address some of the points made in this thread all in one fell swoop, but this whole discussion is arguably off-topic from the original intent of thread; if you wish to discuss this further feel free to contact me via PM or e-mail, or post in any of the Aeon or Nautilus threads of mine, as this is not the place for that sort of discussion.
-Enrique
(By the way, the names of all the lights I've ever made are the CR2 Ion, Nautilus, and Aeon.
Not the ION, and not the AEON - the names were not intended to be yelled when spoken. :nana
