Understanding the power demands of your robot
Most commonly, an Arduino robot requires electric power on at least two voltage levels:
- Low voltage (LV) or logic voltage of 5V or 3.3V (or both) for the electronic components
- High voltage (HV) or motor voltage for the electric motors—for example, 12V
Depending on the specific components of your robot, other intermediate voltage levels might also be required. Some sensors or analog circuits need an additional input voltage that is lower or higher than their logic voltage. Before you start designing the power system, you need to understand what voltage levels are required for your robot and how much current your robot will draw from them. As a rule of thumb, the current required at the low-voltage level is typically small, and the current drawn at the motor voltage level is orders of magnitude higher. For example, the ATMega microcontroller inside your Arduino Uno consumes around 0.1 W (or 100 milliwatts) of power...
