There are surprisingly few options out there for tracking details about your battery via live wallpaper (and those that are out there are quite ugly), but Battery Core seems to fill the niche quite nicely. The live wallpaper consists of a large, Tron-ish rotating disc, the speed of which varies by your remaining charge. Slow rotation means a low battery, whereas higher velocity means higher capacity. You also get text readouts of the level, charging / not charging status, voltage, and battery temperature. A sliding bar at the bottom indicates your current amount of charge, as well.
The app works on both phones and tablets, and the amount of customization you're able to perform is significant. Sprites and glowing be disabled, basically every color can be adjusted, and you can even scale the circle for your particular display. Some of the features (notably, color changes) do require the $1 paid version of the app in order to be changed. The app ran very smoothly on both devices I tested it on, as well.
Head to the Play Store to grab it now.