Charge your Shell with any USB-C charger.
If you don't trust your charger or computer's USB-C port, disable USB data to keep your Shell air-gapped while charging.
Your Shell draws a maximum of 500mA and doesn't engage in USB-C power negotiations.
Shell has a small LED that shows the charging state. When you plug in a USB-C cable to charge the battery, the LED turns red while the battery is charging. Once the battery is fully charged, the LED turns off.