Method of Selecting the right battery for the Project

Method of Selecting the right battery for the Project 

The selection of a proper battery is an important task in power management. Battery having specifications below the required one may lead to failure in the operation of the project. But on the other hand, batteries with specifications overwhelming the required specification of the project may lead to great disaster and may blow out the whole circuitry due to excessive current flows through circuitry.

So, it is advised to select the optimal battery for the project. Here the question arises how one can select the proper battery? The answer to this question will be found in the upcoming sections.

The battery with a good rating and voltage requirements will be chosen. Now which rating battery should be chosen? And how to find the required rating of the battery? The answer is proper power management of the project.

You will need to find the exact power wattage of the project’s component. Once the power rating of each component is found, summed it up to get the total power of the project. But the power management should be done for the worst-case scenario. Make sure that you have considered every component even a single LED. Once the total power rating of the project is found out then it’s time to find the maximum current from the power rating and voltage (the intersection of the voltage rating of every component) by using power-law i.e. P=IV by taking the voltage to the other side of the equality.

Now the maximum current required for the project is determined. This is time to think of the battery rating. Now let suppose you need surveillance for 1hr then the current should be multiplied to 1 which will result in the battery rating for the project.

As an example, let’s take the following components and their power rating.

• Raspberry pi 3 B+ having a power rating of 12.5W, 5V
• Servo a motor having a power rating of 4.8W, 4.8-6V 
• Pi The camera having a power rating of 0.75W 
• 2 white LEDs for indications having power rating 200mW

Summing up the total watts of the above components results in 18.25W since the 5V device is easily available, so it is good to take the 5V supply for the above components (clearly, from the above the voltage should be selected as the intersection of both 5V and the 4.8-6V).

Finding out the current using the formula I=P/V the maximum current is drawn can be found out. Now if the surveillance is only limited to one hour then multiplying the current with 1 to get the value i.e. 3.65Ah for battery rating.

For the surveillance of 1hr, the project is designed, but after one hour the battery will be fully discharged which is not required. So, the battery should not be fully discharged for better life and span. The battery should not be discharged below 50% of the full charged value. So, for that case, we need a double rating so that to work on the project for one hour. Thus, we consider roughly the 7300mAh rating for the battery. Now it’s up to the battery availability in the market. We may select 7500mAh or maybe higher (for a higher lifetime) but not below 7000mAh (then it will lead to the reduction of the lifetime of the project). However, we can use any either a power bank or battery (having the same specifications) and/or a pack of cells. This is how to select a battery/power bank for the project.