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Battery Pack 101

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What is a 'battery pack?' I have been asked this question many times. Often the term 'battery' and 'battery pack' is being used interchangeably. I thought this could be an interesting topic to write about. We will try to cover the following topics in this blog post: What is a battery pack? What components/systems does a battery pack contain? Block level diagram of a typical battery pack Battery Management System *I will specifically talk about Lithium-ion battery packs. some of the concepts may not hold true for other battery chemistries like Lead-acid, NiMH, NiCd etc.   Let's begin with what's a battery pack? Figure 1 As shown in the above diagram, The term 'cell' refers to a single energy storage device.  When one or more cells are connected in a series-parallel connection, a whole assembly is called a 'battery' or 'battery pack'. As said before, a battery pack may consist of one or more cells. The numb...
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Decoding Li-ion Cell Voltages Of Different Chemistries

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While deciding an optimal Lithium-ion cell chemistry for different applications, I came across this question quite a few times, ' Why different Li-ion cell chemistries have different terminal voltages? ' There are numerous LiB chemistry types available in the market. e.g. Lithium Cobalt Oxide (LCO), Li Nickel Cobalt Aluminum Oxide (NCA), Lithium Tantalate Oxide (LTO), Lithium Iron Phosphate (LFP), etc to name a few. However, each and every battery type has its positive-negative points. Although the working principle of all these chemistries is the same, their terminal voltages are different. For example, LCO cells can go up to 4.25V, NCA can be charged up to 4.2V whereas LFP and LTO type cells can have a maximum of 3.8V and ~2.5V respectively. This difference in the voltage has a very large effect on the battery capacity (since energy capacity is directly proportional to the battery voltage). In this blog, I will answer 'Why different LiB chemistries have different ...
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The Problem With Fast Charging

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One of the major drawbacks of EV over the IC engine vehicle is charging time. As we know filling the gasolene tank only takes a few minutes. however, for the same drive range, it takes about an hour for an EV to recharge itself even with a fast charger. In this blog, I will discuss some of the problems with fast charging in the case of LiB. Before we dive into what happens inside LiB when we try to fast charge, I would like to talk a bit about LiB construction.  LiB Construction In my previous blog, ' How Does The LiB Work? ', I indicated LiB as a simple construction with 2 electrodes (Anode and Cathode) placed in an electrolyte. As shown in figure 1. Figure 1. Oversimplified LiB However, the construction of an actual Lithium-ion cell is not at all like what I have shown above! In an actual cell, Anode and Cathode are placed very close to each other in order to pack as much active material (material which takes part in intercalation/de-intercalation) as poss...
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