Bot-Logic Power SupplyWith the BOT-LOGIC Shield there is no need to have one battery to run the Arduino and another for your Servos. The On Board Hi efficiency Switching Power Supply can use a Battery Pack from 4.5V to 20 volts and convert it to a steady 7.0V into your Arduino Vin pin. This voltage keeps your arduino Running cool and the power Supply can Keep on suppling this 7.0  volts to the arduino even if the battery voltages drops as low as 3.0V this will keep your arduino Running reliably even when you are drawing lots of power for running servos.

Important note:
1.) The 7.0 Volts is used to run the Arduino and not the Servos. the Servos get the Battery voltage through a fuse. so your servos need to be able to handle whatever battery voltage you choose to connect to the BOT-LOGIC Shield.  
2.) The normal Vin connector is Blocked by a Spade LUG connector This is to prevent anyone from connecting a power supply to the Power Jack on the Arduino Because Applying Power to  this connector while it is Connected to the BOT-LOGIC Shield could damage the Shield and may also Dammage the Arduino. The Spade Lug is not connected electrically and Serves no other function.