It is normal that you are experiencing brownouts if you assume 500 mA is available. If you power a RPi via micro USB, then the 500mA budget is shared between t

It is normal that you are experiencing brownouts if you assume 500 mA is available. If you power a RPi via micro USB, then the 500mA budget is shared between the RPi and all your peripherals. Your post doesn't say which RPi model you have, but a B+ or a gen2 B will draw anywhere from 230-420 mA idle, so your periphals only have 80-270 mA available. [1] http://www.midwesternmac.com/blogs/jeff-geerling/raspberry-pi-zero-power http://www.midwesternmac.com/blogs/jeff-geerling/raspberry-p...