USB port to 3.5mm DC cable

This is a USB port to 3.5mm DC cable as shown in the photo.

A cheap way to activate or charge your DIY solar panel battery charger control board

Take note that charging using the solar battery using this USB cable will take much longer than a DC wall charger due to the limited power output of USB port. Can also be used to charge any 3.5mm DC 5V devices via USB, e.g. via USB car charger or computer.