Based on the description on their site, the controller includes a built-in battery: "8.39 Wh Li-ion battery, 35+ hours of gameplay... "
That was disappointing for me. Specially condidering the Steam Frame's controllers make use of AA batteries: "One replaceable AA battery per controller, 40hr battery life"
AA Batteries might not be as convenient to use, but being able to replace them is a great advantage. All my Xbox360 controllers still work fine, but none of my PS3' Dualshock 3s.
The official docking station could be used to recharge (rechargables) AA batteries so the functionality could remain the same.
Not enough power? Where did you get that idea? If they used more power than a AA could output they would suck and they'd die instantly.
You might be replying to a wrong comment? But I think the OC meant that a bigger lithium battery can provide more power for rumble and such, compared to AAs.
I did not reply to the wrong comment. Again, if the controller used that much power, it would die instantly.