The mileage and performance of an Electric Vehicle depends on the capacity and efficiency of its Battery Pack. To maintain the battery pack in full health is the responsibility of the Battery Management System (BMS). A BMS is a sophisticated unit in an EV which does a lot of activity like monitoring the cells, balancing them and even protecting them from temperature changes.   To do anything, the first step for the BMS would be to know the current status of the cells in the Lithium battery pack. This is done by measuring the voltage and current (sometimes temperature also) of the cells in the pack. Only with these two values the BMS could calculate the SOC or SOH and perform cell balancing etc. So measuring the voltage and current of cell is vital for any BMS circuit, be it a simple power bank or laptop battery or as complicated pack as EV/Solar batteries.   In this project we will learn how we can measure the individual cell voltage of the cells used in a Lithium battery pack. For the sake of this project, we will use four lithium 18650 cells connected in series to form a battery pack and design a simple circuit to measure the individual cell voltages and display it on LCD screen using Arduino.

 

The objectives of the project include:

• Measuring and monitoring the individual cell voltage on LCD module.
• To achieve this task using Arduino NANO Microcontroller.
• It is very useful to the EV vehicles.

The major building blocks of the project are:

• Regulated power supply.
• ARDUINO NANO Microcontroller
• LCD display.
• Lithium Battery Pack.
• Op-Amp Circuit.

Software’s used:

1. Arduino IDE for compiling and dumping code into Microcontroller
2. Express SCH for Circuit design.
3. Embedded C Language.

     

   

Block diagram:    

   

     

 

video: