Embedded Systems and Design & Development - Feb 6, 2026 | Afternoon | VisionAstraa EV Academy

Battery Design and Configuration Overview

Introduction to Battery Parameters

• The session begins with an overview of battery parameters, specifically focusing on NMC 48 and LFP configurations.

• A comparison is made between different battery types, highlighting the dimensions of the cells (18 mm width, 650 mm height).

Battery Pack Design

• Discussion on the design of a battery pack featuring a series combination of 13 cells.

• Explanation of spot welding techniques used for cell connections, emphasizing the use of nickel strips.

Types of Nickel Strips

• Two types of nickel strips are introduced: single stretch and H-type nickel strips.

• The width specifications for nickel strips designed for 18650 cells are noted as approximately 18 mm.

Transition to LFP Pack Design

• The focus shifts towards designing a battery pack for LFP (Lithium Iron Phosphate), considering both 48V and 60V options.

• Decision made to proceed with a design for a 48V configuration.

Calculating Cell Requirements

• For a configuration requiring 4P (parallel), it is established that each cell has a capacity of 6000 mAh.

• Calculation reveals that an S rating is needed; nominal voltage for LFP is confirmed at 3.2V.

Finalizing Battery Specifications

• It’s concluded that an S rating of around 15 is necessary for the design.

• Total number of cells required in this configuration amounts to 60 (15S x 4P).

Designing Compact Battery Packs

Practical Application in Engineering

• Emphasis on practical knowledge application in designing compact battery packs suitable for devices like phones.

Series and Parallel Connections Explained

• Detailed explanation on how to connect cells in parallel first before creating series combinations, ensuring proper voltage output.

Visualizing Connections

• Description provided on connecting multiple packs together while maintaining correct polarity during series connections.

Simplifying Designs

• Discussion encourages engineers to think creatively about simplifying designs by stacking connections vertically rather than expanding horizontally.

Battery Pack Assembly and Calculation Insights

Overview of Battery Cell Requirements

• The assembly process for the battery pack begins with a requirement for 60 LFP cells configured in a 15s4p arrangement.

• A query is raised regarding the total watt-hour (Wh) and kilowatt-hour (kWh) capacity of the battery pack, indicating a need for calculations to determine these values.

Understanding Power Calculations

• The discussion emphasizes understanding how to calculate watt-hours and kilowatt-hours based on voltage and ampere-hours.

• The basic requirement established is a 48V output with a capacity of 20Ah, leading to questions about calculating total energy storage.

• The formula for power (P = V × I) is introduced, where voltage (V) is multiplied by ampere-hours (Ah), replacing current (I).

Detailed Calculation Steps

• Using the provided values, the calculation shows that 48V multiplied by 24Ah results in an energy output of 1152 Wh or approximately 1.152 kWh.

• Clarification on converting watt-seconds to kilowatt-hours reinforces understanding of energy measurement.

Assembling Battery Cells

• The assembly process involves placing cells into holders; it’s noted that there are specific counts for how many cells can fit into designated holders.

• A count reveals that up to 72 cells can be placed in one holder configuration, while another allows only for 50 cells due to size differences between LFP and NMC batteries.

Size Comparison Between Cell Types

• It’s concluded that LFP cell sizes are larger than NMC cell sizes, which may affect overall battery design considerations.

• Both types have been tested at a similar voltage level (48V), but their physical dimensions differ significantly.

Practical Assembly Considerations

• An overview of LFP cell specifications includes dimensions and other relevant details necessary for assembly.

• The assembly method discussed involves connecting four cells in parallel using designated positive terminals first, streamlining the design process.

Handling Damaged Cells

• It’s mentioned that damaged or "dead" cells will be used during this session's assembly to avoid complications from potential connection errors encountered previously.

This structured approach provides clarity on both theoretical calculations related to battery packs as well as practical steps involved in assembling them.

Battery Pack Design and Assembly

Assembling Cells: Positive and Negative Directions

• The assembly process begins with determining the direction of the cells, deciding that the first cell should be negative, followed by a positive cell.

• Emphasizes the importance of correctly assembling cells in alternating positive and negative orientations to avoid runtime errors; one mistake can ruin the entire design.

• A total of nine series have been combined so far, prompting a discussion on calculating total voltage based on connected cells.

Voltage Calculation and Cell Specifications

• The nominal specifications of the cells are discussed, revealing they are 6,000 mAh with a nominal voltage of 3.2 volts; this information is crucial for understanding overall pack performance.

• Identifies an error in design regarding cell orientation; confirms that ten series have been completed but five more need to be added for optimal configuration.

Verification and Design Simplification

• The speaker checks if all cells are placed correctly from top to bottom, ensuring proper alternation between positive and negative connections throughout fifteen series.

• Visual representation of the battery pack is provided; stresses that while complexity exists in design, there’s a desire for simplification without compromising functionality.

Compact Design Considerations

• Discusses strategies to reduce battery pack length while maintaining efficiency; emphasizes insulation use as a method to achieve compactness without altering cell size.

• Plans to add additional cells into existing space while simplifying connections; aims for an efficient layout that minimizes height.

Finalizing Connections and Series Configuration

• Explains how adding four more cells could allow for two additional series configurations while maintaining parallel combinations already established.

• Questions arise about connection points—whether to join at the top or bottom—highlighting potential mistakes if not done correctly.

This structured approach provides clarity on key concepts related to battery pack assembly, emphasizing both technical details and practical considerations in design.

Battery Design: Understanding Series and Parallel Combinations

Introduction to Parallel and Series Combinations

• The discussion begins with an overview of parallel combinations in battery design, emphasizing the need for clarity in understanding connections.

• A critical examination of a specific design reveals issues with negative and positive connections, highlighting the simultaneous occurrence of both series and parallel combinations.

Configuration of Battery Cells

• The speaker explains how four cells are connected in parallel while also being part of a series configuration, illustrating the complexity of battery designs.

• The session emphasizes that both series and parallel configurations can coexist within a single design, enhancing efficiency.

Practical Applications and Design Considerations

• Engineers are encouraged to explore various configurations to optimize battery pack designs, reflecting on 19 years of experience in creating a 15S4P pack for 48 volts.

• Discussion shifts to calculating total voltage based on visible components within the pack, stressing the importance of understanding nominal voltage.

Nickel Strip Types and Their Role

• An introduction to different types of nickel strips used in battery construction is provided, specifically focusing on H-type strips.

• Both H-type and straight nickel strips are discussed as essential components for achieving effective series and parallel combinations.

Designing for Specific Applications

• The necessity for designing battery packs with varying dimensions is highlighted; width constraints may require longer designs depending on application needs (e.g., bicycles).

• Emphasis is placed on adapting designs based on practical requirements while maintaining functionality.

Conclusion: Key Components in Battery Systems

• The session concludes by summarizing key components involved in battery systems: MCU, BLC motor, throttle, and their interconnections.

• Insights into motor operation reveal that it relies on three windings powered through MOSFET switching mechanisms.

Throttle Mechanism in Electric Vehicles

Understanding Throttle Functionality

• The throttle's operation is crucial for understanding how power is transmitted from the battery to the motor, which will be explored in detail.

• A typical throttle includes a gripper mounted on the vehicle, equipped with a sensor that measures resistance as it is twisted.

• The throttle operates based on resistance values; examples include 0 ohms, 50 ohms, and 100 ohms, affecting current flow and speed.

Resistance and Current Flow

• At zero throttle position (maximum resistance), current flow is minimal. Conversely, at maximum throttle (minimum resistance), current flow increases significantly.

• The relationship between resistance and current flow is inversely proportional: higher resistance results in lower current and speed.

Speed Control via Throttle

• Speed (RPM) correlates directly with current; thus, less resistance leads to higher speeds while more resistance results in slower speeds.

• When the throttle's resistance is at its maximum, both current and speed are minimized. This principle governs how throttling affects vehicle acceleration.

Signal Transmission to MCU

• The throttle sends signals to the Microcontroller Unit (MCU), indicating its position through color-coded wiring: red for positive, black for ground, and green for signal.

• If the initial condition shows maximum resistance when starting the vehicle, it prevents uncontrolled motor activation by ensuring low initial current flow.

Interconnection of Components

• As the driver throttles down (reducing resistance), current increases gradually allowing controlled acceleration of the vehicle.

• Understanding this interplay among components—throttle, battery, MCU, and motor—is essential for grasping electric vehicle functionality.

Wiring Harness Role

Importance of Wiring Harness

• The wiring harness connects various components like battery to MCU and MCU to motor/throttle systems. It plays a critical role in system integration.

Key Components Overview

• Major components discussed include:

• Battery

• Microcontroller Unit (MCU)

• Brushless DC Hub Motor

• Throttle

• Wiring Harness

Vehicle Control Unit Explained

What is VCU?

• The Vehicle Control Unit (VCU), not Voltage Control Unit as commonly mistaken, manages all interconnected components within an electric vehicle system.

Functions of VCU

• The VCU oversees component protection including Battery Management System (BMS), which ensures temperature regulation and safety across all parts of the electric vehicle.

Understanding the Role of VCU in Electric Vehicles

Lack of Safety Devices

• The current system lacks protective devices for critical components like MOSFETs, MCUs, and BLC motors. This absence raises concerns about safety during temperature fluctuations or mechanical jams.

Functionality of VCU

• The Vehicle Control Unit (VCU) connects all individual parts, monitoring their performance and operating temperatures to ensure smooth operation.

• Smart features such as fall alerts are enabled by the VCU, which sends notifications to users if the vehicle experiences a fall.

Integration with IoT

• The VCU communicates with an Internet of Things (IoT) device, facilitating cloud communication that enhances connectivity with mobile phones.

• Students will learn how data flows from the VCU to IoT systems and how this integration is designed in upcoming sessions.

Importance of Understanding Basics

• A comprehensive understanding of basic components like battery packs, Battery Management Systems (BMS), and MCU functionality is crucial for designing and programming a VCU.

• Knowledge about how various components interact is essential for effective development; without it, creating a functional VCU is not feasible.

Feedback and Learning Resources

• Participants are encouraged to provide feedback on their learning experience through a link that will be shared later.

• There will be options available for students regarding whether they prefer detailed notes or presentations; both resources aim to enhance understanding of the material covered.

Conclusion and Next Steps

• After submitting feedback forms, participants will receive access to presentation materials that summarize key concepts discussed in class.