Batteries in Electric Vehicles-Introduction and Fundamentals

This lecture surveys lead-acid, lithium-ion, and nickel metal hydride batteries, their use in automobiles, UPS, and drones, and notes lithium-ion’s higher energy density and smaller size than lead-acid.

Lead-acid batteries power autos (52%), motorcycles (6%), starter batteries (10% for UPS), and support 24/7 operation in hospitals, banks, data centers, forklifts, e-bikes, and solar applications.

Explore how lithium ion batteries operate, mirror lead acid functions, and power diverse applications from consumer electronics to space, defense, and military, plus energy storage, mining, and transportation.

Review the cost trajectory of lithium-ion batteries, which dropped about 80 percent over eight years, with projections of further reductions and broader adoption in electric vehicles by 2050.

Explore battery architecture from cell to module to pack, using Tesla's 8,256 cells in 16 modules to illustrate how this arrangement enables around 100 kilowatt energy and a 300-range.

Trace the history of batteries through the first electrochemical battery, a copper and zinc plate stack separated by paper disks, which produced a current and revealed voltage as chemical reactions.

Batteries convert chemical energy to electrical energy via oxidation at the anode and reduction at the cathode, driving electrons through a circuit to power devices and vehicles.

Explore the internal architecture of a lithium ion battery, including the cathode, anode, and separators. See how electrons move inside the cell.

Explore battery pack architecture, comparing battery modules to monolithic packs, and how modular design eases manufacturing, cooling, and maintenance, with a 14s pack example and module replacement benefits.

Explore the anatomy of a battery pack, including 18650 cells, cooling, the battery management unit, and PSU, and how safety procedures shape its size and performance in Tesla Model S.

Explore the latest cell chemistries of lithium ion batteries, including lithium cobalt oxide, NMC, NCA, LPF, and MTBE (lithium titanium). Compare energy, voltage, rates, temperature, cycle life, safety, and cost.

Learn about lithium cobalt oxide batteries, their high specific energy for mobile devices, and how limited lifespan, thermal stability, and cobalt blending with nickel, manganese, and aluminium affect performance.

Explore lithium magnesium oxide with the LML architecture, a three-dimensional spinal structure that lowers internal resistance and enables fast charging. It supports design optimization for longer lifespan and higher capacity.

Explore nickel magnesium cobalt oxide lithium-ion systems, including 18650 cells around 2800 mAh for moderate loads, and 1:1:1 cathode blends balancing cost and performance.

Explains NC lithium nickel cobalt aluminium oxide battery, used since 1999 for special applications, highlighting six characteristics and similarities to NMC with high energy and decent power, yet shorter lifespan.

Explore lithium phosphate, enabled by nanoscale phosphate cathode materials, delivering high current, strong safety, and tolerance to abuse. Its lower nominal voltage and higher self-discharge affect specific energy and balancing.

Explore lithium polymer batteries, a lithium ion technology with a gel polymer electrolyte that enables high specific energy and weight-reduced, flexible shapes for mobile devices and radio controlled aircrafts.

Explore the size and shapes of secondary lithium-ion cells—cylindrical, prismatic, and pouch—highlighting manufacturing ease, thermal behavior, cycle life, space use, and safety concerns.

Explore cylindrical cell sizes used in electric vehicles, including 18 650 and 21 700, comparing volumes and capacities (16 cm³ and 3000 mAh vs 24 cm³ and 6000 mAh).

Learn how electric chargers transfer electricity from wall sockets to devices, and how current, wattage, and charger ratings influence charging time and speed for batteries in electric vehicles.

Explain the battery charging curve with constant current and constant voltage phases, where current remains as voltage rises to 4.0 V, then stops when current falls below 3% of rated.

Learn li-ion battery charging guidelines for electric vehicles: never charge when the battery is on, avoid parasitic loads. Partial charging can extend life and reduce explosion risk.

Examine how ambient temperature affects lithium-ion battery life cycles. At 25°c, about 85% capacity remains after 1000 cycles; at 45°c, about 80% remains, defining the lower limit for EV use.

Understand depth of discharge as the percentage of lithium ion battery capacity that has been discharged. Excessive discharge shortens lifespan, so manufacturers specify recommended depth for optimal performance.

Explore how electric vehicle charging standards safeguard safety and compatibility, detailing J1772 type 1 single-phase and 62196 three-phase schemes and the charger size defined by these standards.

Explore home charging options for electric vehicles, including level 1 and level 2 charging. Use a standard 120-volt outlet or a 240-volt outlet to adjust charging times.

Home charging cuts costs as home electricity is cheaper than commercial rates, especially at night. A full 30 kWh battery provides about 100 miles of range for daily needs.

Workplace charging gives employees daytime access to employer parking charging stations, offering 5–6 hours daily to extend EV range; reserve parking is encouraged amid limited availability and higher electricity costs.

Combine workplace and home charging to effectively double the electric range for plug-in hybrids, reducing fuel costs with level 2 workplace charging and government subsidies that encourage employers.

Explore CHAdeMO, a DC fast charging standard enabling seamless car-charger communication for charging, developed by TEPCO, Nissan, Fuji Heavy Industries, and Toyota with plans for 400 kilowatt hour fast charging.

Explain the CHAdeMO protocol for high power dc charging and its implications for safety, future-proof design, and universal compatibility across networks and plug configurations.

Explore CHAdeMO battery protection, learning how to control output current for fast charging while preserving battery life through reliable communication and accurate current measurement.

Explore the CHAdeMO charging control failsafe, illustrating how broken pilot signals or grounding lines can trigger immediate DC output shutdown to prevent unsafe charging.

Explain the CHAdeMO interlock of the connector for high-powered EV chargers, detailing automatic safety checks, a mechanical latch, and an electrical lock that releases only after safe conditions are verified.

Explore how the battery management system protects packs, monitors cells, balances them, manages thermal cooling, provides digital-analog output controls, and logs data to report state of charge.

Explain the key functions of the BMS: measure voltage, current, and temperature; control temperature and voltage; communicate battery data; and diagnose faults to maintain safe operation.

Monitor every cell's voltage, temperature, state of charge, and health to protect the pack, balance cells, and manage charging, cooling, and regenerative braking energy routing.

Explore how a battery management system protects lithium‑ion cells by monitoring voltage and temperature, opening charge or discharge switches to keep the battery within safe operating limits and extend life.

Explore centralized, distributed, and modular BMS topologies, outlining cost, scalability, and wiring trade-offs, and show how tight integration with charging, thermal management, and safety subsystems supports EVs and stationary apps.

Examine a sample block diagram of a battery management system, showing 16 cells per module connected to a central controller, with voltage, current, temperature measurement, and inter-module communication for protection.

Explore the battery management system basics, including relays and contacts for open/closed circuits, fuses for protection, and current sensing methods via hall effect sensors and shunt resistors.

The lecture covers a dc pre-charge circuit that protects the battery system by limiting current as a capacitor charges.

Understand why cell balancing matters in lithium-ion battery packs for electric vehicles, ensuring each cell reaches equal voltage despite manufacturing differences, improving depth of discharge, life cycles, and safety.

Unbalanced cells arise as aging increases internal resistance and temperature differences cause uneven charge; external cell balancing systems restore equal current and prolong battery life.

Use passive cell balancing to classify into four categories, employing bypass switches and dummy loads to discharge higher cells, highlighting heat dissipation and charge-limiting strategies.

Explore active versus passive cell balancing, including flying capacitors and inductive flyback methods, their switching schemes, efficiency losses, and modern lossless balancing and redox shuttle concepts.

Learn why cell balancing is needed in electric vehicle batteries and how a microcontroller-based three-type balancing algorithm equalizes voltages during charging, referencing state of charge and battery management.

Understand balance current requirements for battery packs, including cross and maintenance balancing for mismatched cells; leakage and self-discharge govern current levels.

Explore the wire harness and connectors in electric vehicle battery packs, including cables, clamps, tubes, and heat shrink, and how they manage vibration, temperature variation, and electrical interconnection.

Explore electric vehicle connectors, including type 1 and type 2 for slow and fast charging, plus DC rapid charging cables, charging points, and portable cables for public networks.

Explore how battery connectors in automotive packs must deliver low resistance, low thermal input joints while withstanding mechanical stresses, and learn how ultrasonic welding enables reliable interconnects for dissimilar materials.

Explain why thermal management is essential for lithium ion battery packs in electric vehicles, and compare surface cooling versus tab cooling and their impact on lifetime.

Thermal management controls internal resistance heating in batteries, preventing safety incidents and excessive power loss. It preserves battery life across temperatures and guides cooling approaches.

Temperature drives battery resistance, heat, and capacity, with subzero temps raising internal resistance and degrading performance, while 15–35 C yields maximum power and preserves lifecycle; SolidWorks supports EV design.

Explore battery thermal management requirements and their impact on the evolving Indian automotive landscape, where startups rise and brand shares shift toward new entrants by 2025–2040.

Explore air-based thermal control for electric vehicle batteries, contrasting passive cooling with no power and active cooling with outside air, including closed-loop systems and fast charging examples.

Examine liquid cooling for EV batteries, including dielectric fluids and aluminium jacketed systems, noting uniform thermal control, strong heat transfer, and design trade-offs for different vehicle sizes.

Understand how phase change material (PCM) cooling manages battery heat by absorbing latent heat during melting and releasing it during refreezing, enabling compact, efficient cooling in electric vehicles.

Thermoelectric cooling uses electric power to create a temperature gradient across the battery, producing a hot side and a cold side as a solid-state refrigerator, but efficiency is 18–30 percent.

Learn to calculate energy and power for a four-wheeler electric vehicle, considering rolling resistance and aerodynamic drag, and size a lithium-ion pack with 20s40p configurations for a 72-volt system.