Interesting points. If you've already invested in the AA format then that will obviously influence your preferences. In my house, AA is the antithesis of standardized. We have exactly 2 devices that use AA. One is a TV remote and the other is a wireless keyboard. Everything else is either AAA, CR123/16340/18350 (they're all similar enough for our purposes here), a few 18650, and the rest are dedicated battery packs that aren't any of those things. I suppose the Streamlight Protac 1L-1AA that's around here somewhere will technically run AAs, but I've never done that and don't intend to since I don't stock that battery size.
If you want easy and reliable, primaries are still the gold standard, regardless of what sort of waste they are perceived to represent. You don't need to think about them. They work when it's cold, they work when it's hot. They work after years (and years and years) in a drawer. They work in single- and multi-cell devices. There is also very little chance I'm putting a rechargeable anything in a WML any time soon, so a stock of CR123 primaries is always on hand for that application.
Have you looked at Malkoff's AA MDC light? If I was shopping for a zombie light that could run AAs, I don't know if I'd find anything better than that.
We're on opposite ends of the spectrum, for sure. It's actually a bit funny that I'm of the polar opposite viewpoint towards batteries, haha.
Eneloop Master Race, haha.
99% of my devices take either AA or AAA. I don't have anything besides flashlights that take weird sizes, haha. What kind of devices are you using? I'm genuinely curious. Heck, I have an AA Xbox controller.
I disagree on primaries. Lithium primaries are better than alkaline (which leak horribly), but I don't find lithium primaries to be super great. While I know people rave about their hot and cold performance, I find eneloops to be adequate for any temperatures I am going to find myself in. I'm sure there are fringe use cases that might be extremely hot or something where you'd be using a remote device - but I am thinking in terms of using a flashlight. If I am in the area, it's within the usable range of eneloops (which, again, I've had only GREAT experiences with in the dead of winter).
While lithium primaries have a decent shelf life, eneloops are kind of right up there. They hold a charge for years, and if you're in doubt, they're easy enough to recharge every few years. As weird as it sounds, I still meet people that don't realize eneloops were a revolutionization of NiMH cells due to their exceptionally low self-discharge rates.
Performance wise, eneloops run like a top. Let's be honest: CR123 batteries have a terrible output curve. They behave a lot like a higher voltage alkaline; starts high, then tanks fast. Eneloops practically regulate themselves. They can have a flat output curve running direct drive. I think the biggest argument against CR123 batteries are their mediocre performance. Heck, apropos this whole topic is that the HDS lights are limited to 1A of draw due to the hilariously bad performance of CR123 cells.
Multi-cell devices is where I think primaries are most problematic, though. Especially if you've had cells for a number of years, the odds of the voltages being a strong match goes way down. Did someone use one cell briefly, then put it back? Has one discharged faster than another? I think that's where eneloops are great. Recharge them every once in a blue moon if you really want, but they're much more likely to be a better match for multi-cell use. Plus, again, CR123 batteries have mediocre performance curves. I'd much rather have an 18650 than a pair of CR123s in a WML. Two cell lights tend to be inefficient, as well, as they don't evenly discharge both cells, so there's some wasted capacity.
I'm also 100% on team rechargeable for a WML. I have two Surefire AA Scouts with eneloops, actually (and they're shockingly good). Primaries are horrible for civilian use, unless you like burning money. Use it for a bit, and you now KNOW you have reduced capacity. Using a rechargeable? Just recharge them, slap them back in. I don't find the mystery capacity of primaries reassuring. Primary cells are popular with Government units because they LOVE burning tax money swapping cells before every outing.
I actually have TWO MDC AA lights
One with the SST-20 at 4000K, and then a new one with a 4500K 519A. The MDC AA is actually my absolute favorite flashlight, haha. It's SO GOOD. Three fantastic modes spaced so well, a lovely beam, great run times, and the indestructibleness of a Malkoff - all on a single eneloop AA!
I think I'd still absolutely love a single AA Rotary with a replaceable boot, though. A single eneloop would be AMAZING for the HUGE amount of low lumens settings the Rotary has, and it wouldn't be a huge deal if it topped out around 120-150 lumens.
