Anki Cozmo / Anki Vector Robot *UPGRADE* 3.7V 600mAh LiPo Rechargeable Battery | eBay
Cozmo and Vector have very similar parts in most cases. They have exactly the same gear system, the same battery, the same spec motors, and even the same arm mechanics. Vectors parts
Vector story with happy ending : r/AnkiVector
Replacing cube battery : r/AnkiVector
How to Replace the Cube Battery for Cozmo & Vector | Kinvert