Weight plays a very crucial role in robotics and if we increase the weight of the robot, then the force required to move it can exponentially go up. Hence, the concept of power to weight ratio comes into play. We always prefer a battery, which is extremely lightweight and delivers a large sum of power in respect to the weight. The equation for the power-to-weight ratio can be defined as follows: Power to weight ratio in watt hour/kg = Maximum Power in watts / Overall weight of battery in kg.

Now, let's say a battery is providing a power of 500 watts and the weight is 5 kg, then the power to weight ratio will be 100 Wh/kg. The higher the power to weight ratio, the better the battery is.