Priedas LEGO® Education EV3 Rechargeable DC Battery 45501L

The lithium ion EV3 Rechargeable DC Battery is designed for use with the EV3 Intelligent Brick and features a capacity of 2,050 mAh. It provides longer run time than AA batteries and can be charged without taking the model apart. The battery is included in the EV3 Education Core Set and has a charge time of around three to four hours. It requires the MINDSTORMS Battery Charger, which is the same charger used for the NXT Rechargeable DC Battery. These are sold separately.

https://catalogs.lego.com/BrandCatalog/BrandCatalogue2HY2016/NBB/LV/