Thanks for all the hints. I tried to use an usb hub as connector between the powerbank and the ESP. The usb hub is a really old one and that device showed clearly that the powerbank was switching off after a few seconds. So i think the problem is, that a device that takes too less current cannot be ...

Hello, I am using a D1 Mini ESP8266 with a DS18B20 temperature sensor an it is working fine as long as i power it with a USB power supply or connected to my PC. I tried to power it with a powerbank and that did not work. I tried several power banks and all showed the same effect. The blue LED lights...