RECHARGEABLE BATTERY FOR NAO® RL HEADLAMP The R1 Lithium-Ion rechargeable battery provides excellent lighting performance for the NAO® RL headlamp, even at low temperatures. It recharges with a type C micro USB port and has a five-level gauge for precise monitoring of the battery charge level. It is equipped with red lighting for visibility from behind and can be used as a spare battery to charge other electronic devices.