Another critical part of every robot is the power supply. From it depends the efficiency of every circuit and the operating time before recharge and. Furthermore, it's the biggest contribution to the total weight of the vehicle.

Many different technologies can be used for both the battery and the power regulator. Each of them has its own pro and cons, there is no unique recipe.
To ensure the best efficiency and the longest life for the battery pack, it's very important to have a good system that detects the battery status and controls the charging cycle.

An example of LiPo batteries with specialized power control circuit.

In this kind of robot the weight is not a very critical issue, so the designer decided to use NiMh battery pack that is more easy to manage.

The main switch with some current conditioning circuits.

The battery status control circuit have also to take care on keeping enough power so the robot is able to return back to the docking station before exhausting.

The main power regulator.