Entitymarck20 Yes, it is the red power LED we are talking about. Read, In the later models (A+, B+, Pi 2 & Pi 3) the power LED ... will flash if the voltage drops below 4.63V. Ref. https://www.raspberrypi-spy.co.uk/2013/02/raspberry-pi-status-leds-explained/
Ordinary telephone chargers are certainly too weak to power the RPis, which MoodleBox recommends - the models 3 and 4. Voltage is not the limitation, BTW the voltage has to be stable 5.1 V, it is the amount of current the supply could deliver that matters. In the models 3 and 4, we are advised to take 2 to 3 A supplies.
What is your RPi model, BTW?