I'm always running out of AA batteries. I use them for wireless keyboards, mice, game controlers, remote controls, clocks. I buy the big family-size packs. I don't have to contend with yet another power adapter that eventually ends up in a box with other orphan adapters that render their original devices useless.
- A plastic cap comes off with no trouble, and reattaches with a simple clip.
- The cap is attached with an elastic band, so you don't have to worry about losing it
- There's a light right on the battery, with a simple key that explains Light On means charging, Slow Flash is 90% charged, Light Off is charged.
It took about 30 minutes to charge one up, and it promises to be good for five hours of use. Not a lot, but if I keep a bunch charging in a USB hub, it's not a big deal. They're also available in 9V, AAA, and a few other sizes.
They run a hefty ~$19/pair, but the way I go through batteries, it'll be worth it. There's a 10-pack discount that brings them down to ~$17. And even though they shipped them from the UK to the US, they only charged a couple of bucks for shipping. With the 10-pack, shipping is included in the price. Nice!