Official confirmation seeing as some people didn't believe the non-removable battery from the patent. (iirc that's where it originated.)
Also confirms there's no form of quick charging for those of you that were hoping that it had a USB-C Power Delivery port. (Although we still don't know if it has a Power Delivery port, still hasn't been specified as one then?)
Edit: To understand better about the battery charging, click the link to read this post from Thraktor: http://m.neogaf.com/showpost.php?p=228323268
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https://www.nintendo.co.jp/hardware/switch/specs/index.html#1
Edit: To understand better about the battery charging, click the link to read this post from Thraktor: http://m.neogaf.com/showpost.php?p=228323268
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Size: Vertical 102mm × horizontal 239mm x thickness 13.9mm (when Joy-Con mounting ※
※ maximum thickness of from analog stick tip to the ZL / ZR projection part is 28.4mm
Mass: Approximately 297g
(Joy-Cons attached: about 398g)
Built-in battery: Lithium-ion battery / battery capacity 4310 mAh
※ The internal battery can not be removed. If it is necessary to exchange it, we will exchange it for a fee at Nintendo service center (online repair reception).
Battery duration: About 2.5 to 6.5 hours
Duration varies depending on the playing software. For example, "Legend of Zelda Breath of the Wild" is about 3 hours.
Charging time: About 3 hours
※ time is when the unit is charging to sleep the body. (Google Translate)
https://www.nintendo.co.jp/hardware/switch/specs/index.html#1