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).