According to a post from NeoGAF user Conkerkid11, the Nintendo Switch Joy-Con controllers will not be accompanied by rechargable grips. Instead, Switch players who want to play games while simultaneously charging Joy-Cons will need to fork out an extra $30 USD.
The reason why this may be a potential issue comes down to comparison with current gen consoles, which already come bundled with controllers that are able to be charged whilst playing. As they are, Joy-Cons are wireless devices that maximise freedom of movement during gameplay, but can only be recharged when they are tethered to the main body of the Nintendo Switch, also called the Dock. Players will be forced to spend an additional $30 for a Joy-Con charging grip, or drop $70 for a Nintendo Switch Pro controller if they want to be able to charge and play.
Currently, the Nintendo Switch bundle includes the Switch Console, Switch Dock, Left and Right Joy-Con Controllers, Joy-Con Wriststraps, Joy-Con Grip (not equivalent to Joy-Con rechargeable Grip), a HDMI Cable and AC Adapter.
From here onward, the question becomes how many hours of wireless gameplay will undocked Joy-Cons allow?