Here is the standard pinout based on dissection of OEM and replacement units. Most J1KND connectors use a 1.25mm pitch JST-style or molded plastic connector with 3 or 4 pins .
If you’re repairing a device that uses a J1KND battery (often found in rugged phones, power banks, or compact IoT devices), understanding the pinout is critical to avoid short circuits or damaging the BMS (Battery Management System). j1knd battery pinout