GS50 can be charged via USB-C with power bank that supports power delivery (45W, 15V, 3A).
Please be noted that:
1.  The power bank needs to support PD (power delivery) 15V, 3A, 45W and is recommended to have a capacity of 30000mah.
2.  Please use USB-C to USB-C cable to connect GS50 and the power bank.
3.  You can simultaneously play video and recharge the projector with a power bank.  We highly recommend using “Eco Mode” or “Low Power Mode” when charging because you can recharge quickly; otherwise “Standard Mode” takes more time. A soft reminder, while using “Eco Mode” or “Low Power Mode”, the projector will automatically lower 30~50% of its brightness (compared to “Standard Mode”).