In 2005 Sanyo introduced Eneloop NiMH rechargeable batteries. Part of their marketing was that they are already charged when you get them and you can use them right away. The reason for this is they charge them at the factory and that the batteries have “low self discharge” (LSD), in other words it takes them much longer to lose a charge sitting on a shelf than other NiMH batteries. Sanyo claimed that Eneloops will retain 85% of their charge after a year. I bought some last year and have no reason to doubt the claim. I have two HP calculators that eat through AAA batteries so I wanted something rechargeable but also something with a fairly long shelf life. I thought it would be good to have a set for my Archos Jukebox too since I have been charging its batteries separately instead of by using the AC adapter it came with (gets very hot and can’t be good for the batteries).
Powerex Maha MH-C9000 Charger
In 2002 I researched and bought a good battery charger called the Maha C-204F. It only does AAA and AA batteries, but it charges them fairly slowly which means they are charged more fully and with less heat (damaging) than the fast chargers that you get at regular stores. 
I had to order the Maha (billed as “the mother of all chargers”) from Thomas Distributing because they aren’t easy to find. It worked great for a couple of years before one side of it went bad and I could only charge two batteries at a time instead of four. Eventually I bought another one just like it from Thomas in 2006. I burned out its AC adapter in Ireland when I plugged it in to a 220 socket, but I had the old adapter, so no problem.
After my dealings with flashlights lately, I also learned some about batteries and particularly NiMH rechargeable batteries. I have been using them for a long time and even got some Sanyo Eneloops in 2008 to use in my calculator because they hold 85% of their charge after year whereas regular NiMH batteries can easily lose 10% per month. After three months of no use you really need to recharge regular NiMH batteries because if they get too low it can damage them. I got some pretty high capacity NiMH batteries to go with Susan’s camera a few years ago and they were toast after maybe a year. They just never held a charge very well. Part of that may have been not adequately breaking them in by charging them and then using them (not all the way down) a few times.
Fenix L2D Flashlight
After upgrading my three mini Maglites and my Snakelight, I realized that what I really needed was a flashlight that could be really bright, but that you could also make not as bright if that was what was needed or if you just wanted the battery to last longer. Maglite actually has a multi-mode LED mini that you can find and which I wrote about more in my Maglite post.
Solar Charger
After doing research on flashlights, I thought it would be neat to get a solar battery charger. Then you could run the flashlights for free! I have links to some solar products on my iPod battery web page. I found a couple of posts on Candlepower Forums about solar chargers and the experts there seemed to wonder what the point is. A decent solar charger will cost nearly $100 which will buy a lot of batteries. If you are camping then you would have to carry the solar charger with you and then leave it in the sun while it charged batteries. Why not carry some extra batteries? Even the better ones will take all day to fully charge 4 AA batteries and that would require full sun and probably moving the solar panel to get the best exposure throughout the day. Will you have time for that?
It is still intriguing. Some of the solar chargers have an internal battery that the panel charges and then you plug your device (iPod, Palm, phone, or battery charger) into a USB jack on the charger (at night I guess) and get juice from the internal battery. That’s good because you don’t want to leave your batteries or your iPod in the sun all day.
One of the better ones may be a folding one made by Powerfilm. The key is to get plenty of area and this one folds out to get extra coverage, but can be folded up to about the size of a wallet. The advantage and problem is that it uses thin film solar cells which won’t crack like the glass ones, but are not as efficient either (so it needs more area). I couldn’t find a whole lot on user experience for these things. Most of the other ones I’ve seen have much less area but are using more efficient solar cells. Some of them are clearly junk and might require several days of sun just to charge a few AA batteries.
The only other use would be for a prolonged power outage, but even then I have a battery charger that can run off of the car lighter and I could probably charge batteries at work and bring them home. Now if the power grid fails for some reason, then it might be nice to have a solar charger, but if that is the case then I might have bigger worries than if my iPod or flashlight will work.
Mini Maglite LED Upgrade
After writing my last entry where I upgraded my Snakelight with a LED bulb that isn’t brighter but stands to last much longer on a charge, I did some more research (mostly at Candlepower Forums. It is crazy how much information is out there on flashlights. And it’s hard not to get caught up as people talk about new technology and fantastically bright flashlights. Also, you have to sort through a lot of posts some of which have outdated information and of course aren’t going to tell you about what the current state of the art is (until you figure out what to look for).
I have two mini Maglite flashlights that use 2 AA batteries (and a third that uses 2 AAA batteries). They are decent on new alkalines but pretty pathetic using rechargeable NiMH batteries which have more capacity but a lower voltage. They now have LED versions available for more more money ($19 at Amazon, $24 at Walmart). I thought about getting one of those but then passed. Also, in 2009 Maglite introduced brighter LED “multi-mode” flashlights that let you use different brightness levels, but these are not easy to find yet: my Home Depot has them (about $22), but not Target or Walmart. The multi-mode miniMag has two brightness levels (in addition to a flashing mode and an SOS mode) with the brighter mode being about 90 lumens.
The LED Mini Maglite is brighter than the old incandescent versions (which are less than $8), but there are upgrades that are even brighter. The Snakelight upgrade was made by Nite-ize and they make upgrades for Maglites too (as does Maglite). But that one gets poor marks too. Then there is a company called Terralux that makes upgrades. They are harder to find, but they have one version that is definitely brighter called a TLE-5 (using a Luxeon 3 LED) and another that is twice as bright as that called the TLE-5EX. The TLE-5 uses a Luxeon LED while the 5EX uses a Cree XR-E LED (though it has used Luxeon K2 and Seoul emitters in the past, so it’s hard to keep the information straight). They claim the 5EX is 140 lumens vs. maybe 10 for the incandescent bulbs.
Anyway, I got the upgrade in the mail today. It didn’t fit in my older Minimag (so old it says Brinkmann instead of Mini Maglite on it; later on I was able to sand down the edges exposing the aluminum base of the upgrade and I got it to fit), so that one will just have to go without an upgrade. But in my newer one, wow! It is really bright. You can’t look at it without probably damaging your eyes. It’s like a small spotlight. I’m very impressed. People say that because it gets very hot that it will dim some after a few minutes of use. Even on a fairly marginal rechargeable batteries it is just as bright. At 3 watts it would only last a couple of hours on a set of good batteries, but that is about the same as the original bulb which is much, much dimmer.
Here is a very informative review with tons of pictures of the TLE-5EX upgrade. They measure the light as being 16 times brighter than the original bulb.