The composition of ev batteries: cells? Modules? Packs? Lets understand properly!
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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.