Both your helmet and remote use the same included charging cable to charge. Just plug it into any USB plug to charge. Please note there's a correct orientation to plug in the charger to the helmet and remote port.
If charged correctly, the remote button will light up Red when charging and Green when fully charged.
The Matrix helmet will show the battery percentage left on its display. The number ascends while charging. When it shows '100' the helmet is fully charged.
On the Street helmet, the height of the (non-blinking) bar increases as it's being charged. When the bar is fully lit, the helmet is fully charged. Below is an example of a half-charged Street helmet during charging.
Charge the helmet and remote simultaneously
You can also charge your remote and Matrix/Street helmet simultaneously. Place the remote in the remote holder section inside your helmet. This correct positioning of the remote is shown inside your helmet.
Then by plugging the charging cable into the helmet, it will act as a charging dock for the remote as well.
When the helmet's battery is critically low and is about to shut off, it will beep several times to inform you its shutting down.
You can watch the video below for more details:
Where to find the charging port on the remote
To get to the charging port, please rotate your remote as shown below and find the charging port underneath.