Basic details about Electric Vehicles and Battery Management System

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We will learn about Electric Vehicles or EV and it’s different types of Batteries like Li-Ion and Battery management system BMS. After that we will see different functions and components of BMS.

“An electric vehicle is a vehicle that uses one or more electric motors or traction motors for propulsion”- Wikipedia

Electric Vechiles are specifically powered through a self-contained battery pack or solar panels or by an electric generator to convert fuel to electricity.

Also, we will see how the battery Management System is an important part of the Electric Vehicles.

What’s in it for me

  1. Electric Vehicles
  2. Battery Technology
  3. Principle of Operation
  4. Classification of Batteries
  5. Selection Criterion for Battery
  6. Li-ion Battery
  7. Battery Management System
  8. Functions of BMS
  9. Components of BMS
  10. Brief Literature Review
  11. Conclusion
  12. FAQ

let’s Start…

1. Electric Vehicles:

1. Why they are needed

Reason 1: The Crude oil is Exhausting

Petrol and Diesel used to run the Vehicles nowdays, but soon this will be a history

For instance crude oil is made by a mixing of hydrocarbons – hydrogen and carbon atoms. Also, it exists in liquid form in underground reservoirs in the tiny spaces within sedimentary rocks.

But, crude oil are available in limited quantity and due to the over usage, they will get exhausted till year 2070 according to Interesting Engineering

Hence, we have to find an alternative for petrol or diesel based Vehicles because crude will not last long.

Reason 2 : Due to Increasing Air Pollution

Electric Vehicles EV are rising because Due to continuous use of oil, air pollution is increasing.

According to a research, 18% of the suspended particulates, 27% of the volatile organic compounds, 28% of Pb, 32% of nitrogen oxides and 62% of the CO of air borne pollution in America are produced due to vehicles with internal combustion engines.

In addition of this, 25% of energy-related CO2 (the principle cause for the greenhouse effect) of all the CO2 in the atmosphere are released from traditional vehicles.

Consequently as the number of people use public and personal transportation is increasing, the amount of air pollution increases every single day.

Also as a result, electric vehicles are becoming more and more popular.

Also see : How to do project on Electricity Generation through speed breakers

2. What is Electric Vehicle

An electric vehicle generally contains the following major components:

Generally n electric motor, a motor controller, a traction battery, a battery management system, a plug-in charger that can be operated separately from the vehicle, a wiring system, a regenerative braking system, a vehicle body and a frame.

3. Battery in Electric Vehicles

The battery management system is one of the most important components, especially when using lithium-ion batteries.

While currently three types of traction batteries are available: the lead-acid, nickel-metal hydride and lithium-ion batteries.

The Lithium-ion batteries have a number of advantages over the other two types of batteries, and generally they perform well if they are operated using an effective battery management system.

Now let’s look in brief at some Battery technologies available for EV

2. Battery Technology:

Shows a battery pack to be used in EVs, but still there are various types of battery available

Generally battery is a device consisting of one or more electrochemical cells with external connections. In order to provide power to electrical devices such as flashlights, mobile phones and electric cars.

When a battery is supplying electric power, its positive terminal is called as cathode and its negative terminal is called as anode.

Specifically the terminal which is marked negative is the source of electrons that will flow through an external electric circuit to the positive terminal.

Whenever a battery is connected to an external electric load. A redox reaction occurs and converts the high-energy reactants to a lower-energy products. Additionally free-energy difference is delivered to the external circuit as electrical energy.

From the history, the term “battery” specifically referred to a device composed of multiple cells, however the usage has evolved to include devices composed of a single cell.


Generally it has two current leads and separate compartment holding electrodes, separator and electrolyte.


Modules are composed of a few cells either by physical attachment or by welding in between cells.


It is composed of modules and generally placed in a single pack containing thermal management.

3. Principle of Operation of batteries:

Batteries convert chemical energy directly to electrical energy instantly.

In many cases, the electrical energy released is the difference in the cohesive or bond energies of the metals, oxides, or molecules while undergoing the electrochemical reaction.

For instance, energy can be stored in Zn or Li, which are high-energy metals because they are not stabilized by d-electron bonding, unlike transition metals.

Batteries are designed such that the energetically favourable redox reaction can occur only if electrons move through the external part of the circuit

4. Classification of Batteries:

Primary Batteries:

Shows different types primary batteries available in the market

Sometimes also called single-use, or “throw-away” batteries because they have to be discarded after they run empty as they can’t be recharged for reuse.

Primary batteries can produce current immediately on assembly. Disposable batteries are intended to be used once and discarded.

Secondary Batteries:

Image of Secondary battery aslo known rechargeable batteries.

Mostly called rechargeable batteries because they can be recharged for reuse. Usually assembled with active materials in the discharged state.

Rechargeable batteries recharges by applying reverse electric current.

5. Selection Criterion for battery in Electric Vehicles:

  1. Firstly selection depends on Ah Capacity
  2. Secondly on Weight
  3. Also Volume of Battery is important
  4. Then comes C – rate
  5. Also depends very much on Life Cycle.
Comparison of Li-ion and Lead acid Batteries.

Hence, according to the selection criteria required for Batteries, Li-ion battery is best suitable.

Different types of batteries that can be used in Electric Vehicle:

  1. Lead Acid
  2. NiCd
  3. NiMh
  4. NaS
  5. Li-ion
  6. Li-po
  7. PbSb Liquid

Here we will discuss in brief only about Li-ion batteries.

6. Li-ion Battery

Image of Lithium ion Battery pack that will be used in EVs with Battery management system BMS.

However Lithium-ion or Li-Ion (lithium polymer batteries) were firstly developed and commercialized for use in laptops and consumer electronics.

But due to their high energy density and long cycle life they have become the lead candidate for to be used in EVs.

Still the traditional lithium-ion batteries include sensitivity to temperature, low temperature power performance, and performance degradation with age.

Due to the volatility of organic electrolytes, the presence of highly oxidized metal oxides, and the thermal instability of the anode SEI layer, traditional lithium-ion batteries possess a fire safety risk if punctured or charged improperly.

These early cells did not accept or supply charge when extremely cold, and so heaters can be necessary in some climates to warm them. Hence, the maturity of this technology is moderate.

In addition, many EV companies like Tesla Roadster (2008) and other cars produced by that company used a modified form of traditional lithium-ion “laptop battery” cells that can be replaced individually as needed.

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7. Battery Management System:

Battery management system BMS is one if the most important part of Electric Vehicles.

The battery management system (BMS) is an electronic regulator that monitors and subsequently controls the charging and discharging of rechargeable batteries.

It is simply battery monitoring and keeping a check on the key operational parameters during charging and discharging such as  voltages, currents and the battery internal and ambient temperature.

The monitoring circuits would normally provide inputs to protection devices which would generate alarms or disconnect the battery from the load or charger during any of the parameters become out of limits.

Battery Management System is combination of sensor, controller, communication and computation hardware with software algorithms designed in contrast to decide the maximum charge/discharge current and duration from the estimation of SOC and SOH of the battery pack.

Lithium Ion Batteries should not be overcharged or over-discharged because this can lead to damaging of the battery, shortening the battery life, and causing fire or explosions.

The battery management system (BMS) with the functions of battery modeling, battery state estimation, battery balancing, etc as a result they are key to protect the battery and optimize the utilization of the battery in EVs.

Electric car batteries play an important role in electric cars to keep going on the road, thus the electric car battery pack needs to be secure from damage because of uneven temperature.

Depending on the electrochemical used in battery, the optimum range is different.

But the ideal optimum temperature of electric car battery is 45°C in order to keep the performance and life for the battery.

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8. Functions of BMS in Electric Vehicles:

A BMS may protect its battery by preventing it from operating outside its safe operating area such as:

Over-current may be different while charging and discharging modes) Over-voltage (during charging) Under-voltage (during discharging).

Especially important for lead–acid and Li-ion cells to Under-temperature, Over-pressure (NiMH batteries), ground fault or leakage current detection (system monitoring that is the high voltage battery gets electrically disconnected from any conductive object touchable to vehicle body)

Also see : Read more about automative BMS on Wikipedia

9. Components of BMS:


  1. Especially made of Safety circuitry
  2. Also contains sensor system
  3. In addition with data acquisition circuit
  4. Moreover equipped with charge control
  5. Also has Communication system
  6. Last but not least thermal managementm system


  1. Firstly SoC (State of charge) determination
  2. Secondly SoH (State of health) determination
  3. Then the software for cell balancing
  4. Also Fault detection softwares
  5. Lastly user interface softwares

10. Brief Literature Review for Electric Vehicles:

Battery management system for electric automobile 

As human are becoming aware of the environment pollution, consequently electric vehicles as a means of transport are getting more and more attention, with good prospects of development.

Battery power is the core component of electric vehicles not only affects the performance but also the safety of electric vehicles.

Two part of Battery : battery pack and BMS

Two parts generally are high-power battery pack and battery management systems. Group refers to a high-power battery output voltage greater than 50V, battery capacity is greater than the 400Wh.

Moreover batteries like NiCd battery, nickel metal hydride batteries and lithium ion battery are used in  electric vehicles.

The Lithium ion battery has a large specific energy, long storage life, no memory effect, no pollution, etc hence it is widely used in an electric vehicle.

On the other hand, in order to ensure safe operation of the traction battery and maximize the performance of the battery pack.

Furthermore the battery management system is characterized by effect, real-time monitoring of each cell voltage and temperature, and cell balance control state.

Refuelable battery-powered electric vehicle:

The electric vehicle energy storage system permits the electric refueling of the electric vehicle likewise an automobile would be refueled with gasoline at a petrol or pump.

Selective refueling may take place for given battery modules by removing them from the battery system and then charging them at home, office or factory.


To sum up we have studied here about the need of the Electric Vehicles in the near future. Also about basics of Electric Vehicles and the types of Batteries that can be used in it.

We have also seen about the components and functions of battery management system.

Battery management system BMS generally improves the performance of the battery pack. We also learn about battery technology. We have also seen parts of BMS.

Also see : If you are an engineering student then you can also read my blog on Gate Examination.

Frequently asked questions

What is Battery Management System?

Battery Management system act as a Brain of the Electrical Vehicle.
It is a type of electronic regulator which generally regulates the charging and discharging of batteries.

What is the use of Battery Management System?

Battery Management System is used in Electrical Vehicle because they provide the status of charging and discharging of the battery pack and protect the battery from damage.

Why we use Li-ion Batteries in Electric Vehicles?

We use Li-ion batteries in Electric Vehicles because of their high energy density and long cycle life they have become the lead candidate for use in EVs.

What is primary batteries and secondary batteries?

Primary Batteries is single-use, or “throw-away” batteries because of they have to be discarded after they run empty as they can’t be recharged for reuse.

Secondary Batteries are rechargeable batteries because they can be recharged for reuse.

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