I bought a $5 usb charger that I am using to power my Raspberry Pi. The charger works decently but I am noticing that every once in while the raspberry pi will reboot. I have read that some chargers that supply 5v often drop under 5volts. Does this mean I need a battery that supplies a little over 5volts? I also read that any voltage over 5 will fry the pi? Can someone explain how to properly select a battery to buy for the Raspberry Pi B?
The best answer would come from the system designer, in this case the Raspberry Pi foundation. You don't say which Raspberry Pi you have. The 3 is notorious for being finicky about voltage drops, the 3b less so in my experience.
The Foundation says "The Raspberry Pi 3 is powered by a +5.1V micro USB supply. Exactly how much current (mA) the Raspberry Pi requires is dependent on what you connect to it. We have found that purchasing a 2.5A power supply from a reputable retailer will provide you with ample power to run your Raspberry Pi."
Note they said 5.1V, not 5V.