Funnily enough, though, while it was the eneloops' ability to deliver constant voltage under load that made them useful to me, it's their shelf‑life that gets the most attention in Sanyo's ad copy. That's because many fully charged NiMH cells go dead after sitting around for only a few months, but eneloops can hang onto a charge for a year or more. In fact, they're advertised as being ready for use right out of the package. It's proven to be a potent selling point, and other manufacturers were understandably quick to follow suit. Eneloops have now been joined on the shelves by other "low self‑discharge" cells. I'm told that these are every bit as good as eneloops, too, but you'll have to look elsewhere for confirmation. I'm sticking to what I know, and I know this: It's a rare month that I shoot fewer than 1000 pictures with my Pentax, yet the same four eneloops almost always last from the beginning of the month to the end. (Note, however, that I seldom use my flash. If you do, you'll go through batteries at a much faster clip.)
The upshot? A single set of freshly‑charged eneloops will see me through most trips, though I always bring along at least one spare set, just in case — either charged eneloops or disposable lithium cells. Neither has let me down.
Now let's turn back to standardization for a minute. There's another point in its favor. Since electronic devices differ in their power needs, sometimes quite dramatically, you can often use "spent" NiMH cells taken from a high‑drain device like a camera in a less demanding application, without recharging. I've have good luck recycling both hand‑me‑down eneloops and nonrechargeable lithium cells from my cameras, using them in flashlights and headlamps, not to mention my Garmin GPS. I don't get the same service I'd get from fresh cells, of course, but I usually get something. It's always worth a try, at any rate.
In fact, if you have an inexpensive multimeter at home, you can even vet batteries before a trip. You may be surprised at the results. I've had lithium cells that were too pooped to power my Pentax still register as "good" on the battery tester, and when I subsequently retasked them for the GPS, they've kept me on the map for hours. Though I'd never rely on second‑hand cells in a critical application, it's good to know that you can practice a sort of trickle‑down energy economics to get the most out of your batteries, extracting every last erg before you put them in the "dead cell" bag for later recharging or disposal.
Ah, yes. Recharging. What do you do when your last cell flatlines? That's where my backcountry energy budget breaks down. If you can't find a current bush to plug in your recharger — and though I keep looking, I've yet to see one — you're going to have to make your own juice. This problem looms especially large when you have one or more high‑drain devices that use proprietary rechargeables. Many digital cameras fall into this category, and laptops are another obvious example. Most are notoriously power‑hungry, and if you insist on keeping your trip journal on your laptop (or even a somewhat more portable tablet), you'll have your work cut out for you just to keep it fed. It's a very good day when I get more than six hours on my laptop before it pulls the plug on me, and even my frugal Kindle e‑book reader needs to be topped up sooner or later. Cell phones are also awkward customers, but unless you've got a couple of teen‑agers or commodities traders in your party, you probably won't be putting many minutes on your phone in the backcountry. A fresh charge should see you through almost any trip. That's not the case with laptops and similar ravenous beasts, of course.
The easiest solution to the problem is just to leave any high‑drain devices that use proprietary or hard‑wired batteries behind when you set off for the put‑in. But if this doesn't appeal, you'll have no choice but to carry some sort of …
It could be as simple as one the ubiquitous battery‑powered cell‑phone chargers, many of which can be used to charge other devices, as well. Or you might opt for something as technically complex as a portable solar power system. Though I own one of the cell‑phone chargers (it uses AA cells to recharge my phone's battery), I've never needed it in the backcountry. I've no experience whatever with any of the various solar chargers, either. Still, since the number of devices I own that use non‑standard rechargeable batteries is steadily increasing, I'm keeping my eyes open, always bearing in mind that if a charger is to be of any use at all, it has to deliver enough current at the right voltage. It also has to have the proper adapter(s). Practicality is another hurdle. While there's no denying the attraction of getting free power from sunlight, sunny days can be rare treats in Canoe Country, even in high summer. Moreover, maximizing the output from any solar panel requires that it track the sun in its arc across the heavens with a fair degree of accuracy. How would I do this on a paddling trip? I don't know.
Then again, the question may be moot. It's possible that I've reached the point of diminishing returns where backcountry electrification is concerned. My best course may well be to make do with devices that use standard AA cells, like my cameras and GPS, supplemented by a few — a very few — current‑sipping gadgets like the Kindle. After all, if I'm content to rely on muscle and wind to move my body from place to place, do I really need to be plugged in every moment of every day? I don't think so. There's a lot to be said for spending a little time out of the loop, after all. "Simplify, simplify." That was Thoreau's advice to anyone in search of the good life. And I think he was onto something.