Embedded Systems and Design & Development - Feb 9, 2026 | Morning | VisionAstraa EV Academy

Embedded Systems & Design — VisionAstraa EV Academy (Feb 9, 2026 morning session)

Scope

• Instructor-led technical lecture covering:
  • Battery fundamentals, pack design, and SOC estimation
  • BMS selection and troubleshooting
  • Motor and controller basics (embedded control)
  • Wiring harnesses and connectors
  • Charger fundamentals, topology, and selection
• Evening session (hands-on) promised: connector mating, charger sockets, live charging demos, and practical troubleshooting.

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Key technological concepts and product/feature guidance

1. Battery basics and pack design

• Battery types
  • Primary (single-use) vs secondary (rechargeable).
  • Chemistry examples: lead-acid, gel, NMC (Li-ion), LFP.
• Cell form factor/spec notation
  • Example: “18650” — 18 = diameter (mm), 650 = height (tenths of mm).
  • Manufacturers provide datasheets with voltages, capacities, internal resistance, cycle life.
• Important per-cell voltages
  • Nominal, full-charge (cell max), cutoff (lower cutoff).
• Pack construction
  • Build parallel sub-packs, then connect those in series to reach pack voltage.
  • Imbalance and missing-cell issues can cause pack health problems.

• State-of-charge (SOC) estimation

  • Rough SOC from pack voltage relative to min/max:

    SOC = (Vpack − Vmin) / (Vmax − Vmin)

  • This is a coarse method; use cell/pack curves or coulomb counting for greater accuracy.

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2. BMS (Battery Management System)

• Selection criteria
  • Number of series cells (S count)
  • Current ratings based on C-rating
  • Cell balancing capability (active vs passive)
• C-rating examples (class examples)
  • Discharge higher (example used: 3C)
  • Charging limited (example used: 0.2C)
• Primary BMS functions
  • Cell voltage monitoring and balancing
  • Over-voltage / under-voltage / over-current protection
  • Charger disconnect when limits are reached
• Troubleshooting notes
  • Instructor listed a finite set of pack/BMS faults; if monitored parameters read normal but pack won’t output, suspect BMS internal failure.
  • Example metric cited in subtitles (~0.009 V cell-to-cell difference) may be a transcription artifact — consult datasheets/vendor guidance for precise thresholds.

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3. Cell balancing

• Two approaches
  • Passive balancing (shunts): bleed energy from higher cells as heat
  • Active balancing: transfer energy between cells
• Choice depends on application; active balancing is often preferred for performance and longevity.

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4. Motors, sensors, and controllers (embedded integration)

• Motor types
  • Mid-drive vs hub motor; internal structure and push-pull magnetic operation discussed.
• Hall sensors
  • Detect rotor position (north polarity triggers output) and provide signals to MCU for commutation.
• Controller hardware and operation
  • Microcontroller + MOSFETs: MCU reads Hall/torque/throttle inputs and switches MOSFET gates to drive three motor phases (e.g., yellow/green/blue).
• Throttle
  • Variable-resistance input controlling motor current/acceleration (higher resistance → lower current initially).
• Controller features
  • Ignition/key, speed sense/display, mode switching (high/low/reverse/parking/hill-hold), and multiple I/O pins for modes and sensors.

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5. Wiring harness and connectors

• Harness: integrated bundle of wires connecting vehicle subsystems.
• Practical connector types and mating (male/female) to be demonstrated in the evening hands-on session.
• Correct connector use is required for safe, maintainable installations.

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6. Charger fundamentals and topology

• Purpose
  • Convert AC mains to DC suitable for the battery pack; include safety, rectification, filtering, and regulation.
• Typical charger block flow (as taught)
  • AC input → safety/protection (fuse, etc.) → rectifier → filter → (inverter/transformer step) → regulation → DC output to battery
• Reason for DC→AC→transform→rectify step in some topologies
  • To reject line disturbances and create a stable regulated DC output for precise charging.
• Safety hardware
  • Fuses and protections to prevent AC-side shorts if internal components fail.

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7. Charging algorithms and profiles

• Two main behaviors emphasized
  • CC (constant current) phase: charger supplies fixed current, pack voltage rises.
  • CV (constant voltage) phase: charger holds voltage at Vmax and current tapers/falls (top-off).
• Common industry profile
  • CC followed by CV (CC-CV). Mismatched charger/battery chemistry targets produce undesirable outcomes.

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8. Charger and BMS matching; chemistry compatibility

• Voltage matching

  • Charger voltage must match pack full-charge voltage:

    Vcharger_max = Nseries × Vcell_full

  • Example: NMC full-charge ≈ 4.2 V per cell.

  • Charging current selection
  • Icharge_max = Ah × Ccharge (class example used Ccharge = 0.2C).
  • BMS discharge selection
  • Idischarge_max = Ah × Cdischarge (class example used 3C).
  • Chemistry differences
  • LFP nominal ≈ 3.2 V, full ≈ 3.6 V per cell (different from NMC).
  • Charging LFP with a charger set for higher NMC voltage risks BMS disconnects and is unsafe to rely on BMS alone.
  • Using an NMC charger on LFP will undercharge the LFP pack, reducing usable range.

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9. Practical considerations and upcoming hands-on content

• Evening session will include live demos:
  • Connector types and correct mating
  • Charger sockets and real-world charger behavior
  • Fast-charging techniques (pulse charging) and connector standards (some socket transcriptions were unclear)
• Emphasis on being able to compute charger specs and BMS sizing quickly from pack Ah and series count.

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Guides, tutorials, and takeaways

How to select a charger (workflow covered in class)

1. Determine chemistry → cell full-charge voltage.
2. Compute series count:
   • Nseries = Vpack_target / Vcell_nominal
   • Vcharger_max = Nseries × Vcell_full
3. Choose charging current:
   • Icharge = Ah × Ccharge (class example Ccharge = 0.2C)
4. Size BMS discharge capability:
   • Idischarge = Ah × Cdischarge (class example Cdischarge = 3C)

Other key takeaways

• Simple SOC estimate from pack voltage using Vmin and Vmax.
• Understand CC-CV charging phases and expected behavior.
• Use a compatibility checklist for charger/BMS/chemistry matching; do not assume safety solely from BMS cutoffs.

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Examples calculated in session

• 60 V NMC, 40 Ah
  • 16S → Vfull = 16 × 4.2 = 67.2 V
  • Icharge_max = 40 Ah × 0.2C = 8 A
  • Idischarge_max = 40 Ah × 3C = 120 A
• 60 V NMC, 26 Ah
  • Vfull = 67.2 V
  • Icharge_max = 26 Ah × 0.2 = 5.2 A
  • Idischarge_max = 26 Ah × 3 = 78 A
• Other pack examples mentioned
  • 48 V (13S) → Vfull ≈ 54.6 V
  • 72 V (20S) → Vfull ≈ 84 V
  • 51.2 V (14S) → Vfull ≈ 58.8 V
• LFP example
  • 60 V LFP ≈ 19S → Vfull ≈ 68.4 V (reflects lower per-cell nominal/full voltages versus NMC)

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Errors and subtitle artifacts (notes)

• Some numeric terms and phrases were garbled in subtitles (e.g., “0.009” as acceptable cell difference — likely transcription error). Use datasheets/BMS vendor guidance for precise thresholds.
• Connector/socket names (e.g., “type six/type five yav sockets”) were transcribed imperfectly; evening demo will clarify exact connector naming and standards.

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Main speakers / sources

• VisionAstraa EV Academy — session instructor (unnamed in subtitles, primary speaker)
• Participant mention: “Makala” (thanked during discussion)