Cameron Sino 2600mah Remote Control Battery Lc18650 For Nvidia P2570, Shield - Digital Batteries - AliExpress
Replacing Shield Controller's internal batteries with an external 2xAA battery pack : r/ShieldAndroidTV
Amazon.com: Replacement Battery for Nvidia Shield Game Controller,Shield TV Game Controller,P2920,fits HFR-50AAJY1900x2(B),HRLR15/51,1800mAh/4.32Wh : Video Games