3500mAh Battery GSP872693 01 for JBL Charge 4 JBL Flip 4, Flip 4 Special Edition+ teardown tool|Digital Batteries| - AliExpress
How to fix audio dropouts through aux | Details | Hackaday.io
3200mAh Battery GSP872693 01 for JBL Charge 4 JBL Flip 4, Flip 4 Special Edition+ teardown tool|Digital Batteries| - AliExpress
JBL Flip 3 battery lasts for a few minutes only although it appears to be fully charged. I've had this speaker for a couple of years and I'm quite fond of it,
ORIGINAL USB FOR REPLACEMENT JBL Flip 4 Part (version TL and GG) | eBay