The Composition of EV Batteries: Cells? Modules? Packs? Let’s Understand Properly!

These days, the electric vehicle market is gradually expanding. Consequently, the interest in lithium ion batteries, the power source EVs, is growing as well. However, we sometimes get confused with the different battery terminologies when reading EV related articles or reports. “Battery cell”, “battery module”, “battery pack”... Although “battery” is the most commonly used name, the aforementioned three words actually refer to different types of batteries.


Today, we will look into the precise definitions of EV battery’s “cell”, “module” and “pack”. 


Electric Vehicle Battery is Composed of “Cell → Module → Pack”


To operate an electric vehicle, an enormous amount of power thousand times stronger than that of a smart phone is required. That is why EVs need from dozens of battery cells up to as many as thousands. The composition of an EV battery might vary slightly depending on the types of electric vehicles, but generally EV batteries are composed of cells, modules and a pack.


In fact, to safely and efficiently manage the countless battery cells mounted in one EV, the cells are installed in forms of modules and packs. Simply put, cells, modules and packs are units of gathered batteries. A cluster of cells make up a module and a cluster of modules make up a pack. Ultimately, in an electric vehicle, one form of battery is installed: a pack.


BMW i3 


Let’s take a look at the example of a typical pure electric vehicle, BMW i3. In a BMW i3, a total of 96 battery cells are installed. Twelve cells are combined into one module and eight modules are put together to go into the vehicle in the form of a pack.


Let's examine each term one by one. A cell which is the basis of a battery must possess high capacity per unit volume in order to show maximum performance in a restricted area inside a vehicle and the cell also needs to have much longer lifespan compared to batteries used in general mobile devices. Furthermore, cells must endure shocks transmitted during the drive and possess high reliability & stability to the extent of being able to withstand high and low temperatures.
When a number of cells are put into a frame to protect them better from external shocks such as heat or vibration, this is called a module. And when a number of modules come together with a BMS (Battery Management System) and a cooling device that control and manage battery’s temperature, voltage, etc., this is called a pack. This is how numerous cells are installed in an electric vehicle through the form of a pack.

<Definition of Electric Vehicle’s Battery Cell – Module – Pack>



Battery Cell, Module and Pack for Samsung SDI EV Battery



Battery pack installed at the bottom layer of BMW i3​

(Composed of 8 Modules and 96 Cells)



Electric Vehicle Battery Market, Now Towards a Competition of “Module & Pack”


Many consumers consider “driving range” as the most important factor when purchasing an EV. Therefore, battery makers are actively pushing forward the development of “high energy density” battery cells in order to put more energy into the same volume. The battery industry is moving towards the direction of cell development that focuses on securing safety whilst enhancing energy density.


As the direction on battery cell development is set to a certain extent, the interest toward module and pack technology is also heating up currently. Industry players are widening their focus scope from cell performance to the efficient design and structure of packs/modules. Since electric vehicle’s power source is in the form of a pack, pack specifications is closely correlated with the overall design of an electric vehicle. As a matter of fact, the design of an electric vehicle can become more stylish and modern depending on how slim the installed battery pack is. This is why the competition for better module/pack designs is getting fiercer not to mention all the efforts for higher battery cell energy density.



Samsung SDI Sets Out to Target the Market with Customized Module/Pack Solutions


Earlier this year, Samsung SDI garnered attention from many automakers when presenting the “integrated battery module”, a module platform for electric vehicles. Based on the prior cell technology, SDI showcased a module that maximizes cell’s efficiency.

Normally, around 12 cells go into a conventional battery module for EVs and the capacity is within the 2~3kWh range. Yet, with the “integrated battery module”, Samsung SDI was able to present a module with 6~8kWh capacity, twice as much as the conventional model by applying a cutting edge equipment design process that allows more than 24 cells to be mounted into one module. 




​Conventional Module (Left) and Integrated Battery Module (Right)

As you can see in the photographs, more cells are mounted into one module and less modules mounted into one pack, decreasing the need for various connection components and saving more space.


Since the number of components and the weight/volume can be reduced compared to the existing modules when installed into a car, the concept was very much welcomed by many auto manufacturers. This shows how the EV industry is now also taking into account the performance of modules besides the high performance of cells.


In addition, Samsung SDI is a forerunner in the development of customized pack solutions which satisfy the various needs of auto manufacturers.


Low Voltage System(LVS), a type of technology that allows the substitution of lead acid batteries or the addition of a battery system in conventional ICE vehicles, is currently under the spotlight. This solution enables the utilization of electric functions based on a relatively minor change in the design of the existing car model leading to ungraded battery performance. The advantage here is that the merits of a hybrid electric vehicle(HEV) can be enjoyed by the maximum utilization of ICE vehicle’s manufactured platform.


Low Voltage System(LVS) Pack


Moreover, various pack technologies for the reduction and optimization of battery space in the EV design, are being developed. New solutions are being created by applying various innovative ideas and state-of-the-art technologies such as directly installing cells to a pack without the need for modules on the designs. As we open the new era of electric vehicles, there will be a variety of different pack models developed to satisfy the demand of diverse automakers’ EV designs. This is part of the battery makers’ flow of being prepared for such future and opening the new age of “battery design” with vast applicable forms of cells, modules and packs.


The concerted effort, time and energy being invested in cell/module/pack technology development means that it will be only a matter of time before greater, more advanced electric vehicles are on sale.


We ask you to keep an eye on Samsung SDI and the remarkable strides our batteries have made, not just in the EV range performance but also as a way to deliver a slimmer, more chic and beautiful electric vehicle design!