Finally found a good battery! After wasting money on cheap chinese knock-offs,I decided to spend some more. Bought these from Aliexpress and they are excellent! : r/PSP
PSP Battery Brand Test and Review for Cameron Sino (?) 1800 mAh and 1200 mAh (AliExpress) : r/PSP
Rechargeable Battery Sony Psp S110 | Psp Battery Pack 3.6v 1200mah Sony - Sony - Aliexpress
Game Console Battery 1800mAh PSP-110 for Sony PSP-1000,PSP-1000G1,PSP -1000G1W,PSP-1000K,PSP-1000KCW,PSP-1001,PSP-1004,PSP-1006
Cameron Sino 1800mah Battery Psp-110 For Sony Psp-1000,psp-1000g1,psp -1000g1w,psp-1000k,psp-1000kcw,psp-1001,psp-1004,psp-1006 - Digital Batteries - AliExpress