A thumbnail is the only tool you need to pop off Tango's rear cover and access the battery. (Well, a thumb would probably be pretty useful, too).

Cover off, battery out. Simple. Tango's development brainpower went into what's inside the phone, not into fancy chamfered edges or curved metal unibody enclosures.

Tango bears a hefty 3000 mAh battery, ready for developers to take it to the limit.

3000 mAh may be big for a smartphone, but if it weren't for the ultra low power requirements of the vision coprocessor powering Tango's 3D imaging, it'd have to be a lot bigger.