There is one unit that we have been using in all our projects, but I want to emphasize on it in this chapter. This unit is the power unit. The reason we are talking about it is because in this chapter we will be controlling multiple servos. When we are talking about multiple servos, naturally we will be talking about a lot of power consumption. In the robot arm, we have six servo motors. Now, depending upon the make and model of the motor, the power consumption will vary. But keeping yourself on a safer side and assuming every servo's power consumption to be around 1 amp would be a good idea. Most of the power supply you would be using might not be able to give you this much of burst current. So what should we do?

We can take the easy approach of taking a higher power output. But, instead, we can take the unconventional route. We can have a battery that can deliver this much of power when needed. But, the question is, will any battery solve our purpose? Obviously, the answer would be no.

There are multiple types of batteries that exist. These batteries can be distinguished based on the following parameters:

• Voltage
• Capacity
• Power to weight ratio
• Maximum charge and discharge rate
• Chemical composition

These are covered in detail in the upcoming subsections.