I'm basically loading up enough batteries to run a USB hub and a webcam. The USB hub is rated at 5 volts. Right now I've connected 8 batteries (these batteries, if relevant) in series and in parallel to output 5.3 volts. Will the extra .3 volts cause problems for the USB hub? The 7805 voltage regulator requires a minimum of 7 volts to output a steady 5 volts, so I was wondering if I should increase the battery voltage and do it that way? (I've been trying to avoid this because I figured there would be significant power loss, is that so?)
The application is a little 6 volt car/robot with a webcam/raspberry pi/wifi USB.
I realize that the hub will probably draw more amperage than my 8 batteries can currently support, so I plan on stacking more batteries if necessary.
Also, I'm thinking of powering the USB hub/raspberry pi by separate battery packs. Is there any reason to connect the grounds to each other since they are on separate circuits?