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.
There is no bigger disappointment than wanting to play some VR and your controller is dead and you have to charge it. Can’t really charge them while playing like on normal controllers either.
So I’m quite happy that they went with AAs this time around. Although I need to pick up some rechargeable AA batteries when the Frame comes out.
That’s fair that you can’t charge them while playing like you could a regular controller I hadn’t really thought of that.