@foone L7805 or LM7805? As a linear regulator the amount of heat it will dissipate will (input_voltage - 5) * current. So if you give it 10V and draw one amp from it the case will be dissipating 5W of heat. (quite toasty and will melt a TO-220 without heatsink) Typical safe dissipation in still air is about 2W so 7A in and 1A draw before you need to add copper.