It has a separate magnetically attached battery / charging unit. I have to charge 5-6 times per "tank" that's attached. The battery side also has a mini-led display showing animations and battery / juice left so it's actually communicating with the tank side. A kit with battery and tank runs me about $25, but the tank alone is about $20. So they add $5 to cover the battery / charging component. It's a vice, but at least with this brand I'm not throwing away batteries weekly.
