Summary of "Embedded Systems and Design & Development - Feb 10, 2026 | Afternoon | VisionAstraa EV Academy"
Summary — Embedded Systems and EV Design
VisionAstraa EV Academy — Feb 10, 2026 (Afternoon)
Overview — Main ideas and lessons
- Recap of basics: battery pack, motor, controller, charger (AC→DC), connectors, harnesses; onboard vs offboard charging overview.
- CCS2 (Combined Charging System 2) explained: single combined socket supporting AC (Type 2 upper portion) and DC (additional lower pins). Male (plug/gun) and female (vehicle inlet) parts described; key pins (L1/L2/L3, N, PE, PP, CP) labeled and discussed.
- How to find and read a cell datasheet, with a practical walkthrough using brand-specific searches.
- Detailed analysis of an example LFP prismatic cell datasheet: converting power/voltage specs into current and C-rate, charging protocol (CCCV), thermal/mechanical specs, and aging indicators.
- Review of cell form-factors and chemistries (cylindrical, prismatic, pouch; INR/ICR/IMR/NCR/LFP), trade-offs (energy density, C-rate, cycle life, cost), and guidance on selecting cells based on application.
- Importance of system-level design: battery pack must match motor, controller, and vehicle requirements (range, peak current). Overspecifying wastes cost/weight; underspecifying risks BMS shutdown or failure.
- Battery health and lifecycle monitoring: internal resistance and cycle counting (via smart BMS) are key metrics.
- Next steps: upcoming sessions focus on embedded systems for EVs (MCU/BMS/VCU) and offline hands-on labs starting Feb 16 (battery assembly, motor teardown, harness work).
Detailed actionable methodology / instructions
1. How to locate a useful cell datasheet
- Identify the manufacturer/brand printed on the cell (e.g., Highstar, Panasonic, LG).
- Search for “[brand] [chemistry] datasheet” (e.g., “Highstar LFP datasheet”) on the manufacturer site or trusted distributor pages.
- Prefer datasheets from official manufacturer sites or trusted datasheet aggregators.
2. Five essential datasheet parameters to extract (for pack design)
- Maximum charging voltage (full-charge voltage; e.g., 3.65 V for the example LFP).
- Nominal voltage (e.g., ~3.2 V for LFP).
- Rated capacity (Ah) and the specified test/discharge conditions (e.g., capacity at 0.5C down to 2.5 V).
- Maximum charging current or maximum charge power (and derivable C-rate).
- Minimum voltage / cut-off voltage (e.g., 2.5 V), plus dimensions and weight.
3. How to convert datasheet power specs into current and C-rate
- Use the relationship P = V × I to calculate current: I = P / V.
- Example: max charge power = 300 W, nominal voltage ≈ 3.2 V → I ≈ 300 / 3.2 ≈ 93.75 A → ≈ 94 A.
- Convert current to C-rate: C = I / Ah.
- Example: 94 A with a 100 Ah cell → 0.94C.
- For short-duration peak discharge: apply the same method to the specified maximum discharge power.
- Example: 600 W / 3.2 V ≈ 187.5 A → ≈ 1.9C for a 100 Ah cell.
4. Interpreting charging method (CCCV) from datasheet
- CCCV = Constant Current then Constant Voltage.
- Typical sequence:
- Charge at the specified constant current (e.g., 0.5C or per datasheet) until voltage reaches the charge-voltage threshold (e.g., 3.65–3.66 V).
- Switch to constant-voltage mode at the full-charge voltage and continue until charging current falls to the termination threshold (e.g., 0.05C).
- Always follow manufacturer-specified temperature and environmental limits for charging/discharging.
5. Initial conditioning / cycle test (example procedure)
- Example test cycle used for datasheet characterization:
- Charge at constant power (150 W) to 3.66 V; rest 30 minutes.
- Discharge at constant power (150 W) to 2.5 V; rest 30 minutes.
- These cycles help determine rated performance and life-cycle behavior.
6. Using datasheet data to choose cells and design a pack
- Steps:
- Determine pack voltage (e.g., 60 V) and desired capacity (Ah) from range requirements.
- Determine peak current demand from the motor/controller.
- Select cell chemistry and form-factor that meet required peak discharge and charge C-rates, cycle life, weight, and cost constraints.
- Guidance:
- Avoid oversizing discharge capability relative to motor demand (adds cost/weight).
- Avoid undersizing (risk of BMS shutdown and poor performance).
- Consider thermal limits (charging/discharging temperatures) and packaging constraints.
7. Assessing cell aging and life cycles
- Internal resistance (impedance) is a primary aging indicator: higher internal resistance → reduced available current and lower health.
- Example fresh prismatic LFP: ~0.6 mΩ; aging raises this value.
- Smart BMS capabilities:
- Track cumulative cycles by integrating current over time.
- Log charge/discharge events and timestamps to estimate remaining life.
- Use trends in internal resistance and cycle count to estimate state-of-health (SOH).
- Manual estimation of cycles or SOH without proper tools is unreliable.
8. Connector / charging socket notes (CCS2 specifics)
- The upper portion of the inlet corresponds to AC Type 2 (L1/L2/L3, N, PE).
- Lower added pins provide DC power (positive/negative) for fast charging — together forming CCS2 (combined AC + DC in one inlet).
- PP and CP pins: pilot/control signaling (protective pilot and control pilot).
- Distinguish male (plug/gun) vs female (vehicle inlet) when considering mating and safety.
Key technical concepts and parameters emphasized
- P = V × I relationships for converting power to current and deriving C-rates.
- C-rate definition: C = charging/discharging current / cell Ah.
- CCCV charging profile and termination thresholds (example: 0.05C).
- Cut-off voltages (full charge and minimum discharge).
- Operating and storage temperature ranges and their impact.
- Internal resistance / impedance and its role in performance and aging.
- Chemistry trade-offs:
- LFP: nominal ~3.2 V, excellent cycle life (thousands of cycles), typically lower discharge C-rate than some NMC cells.
- NMC / NCA / INR / NCR: higher energy density, higher C-rate capability, typically costlier and often fewer cycles than LFP.
- Form-factor trade-offs:
- Pouch: lighter and flexible, less mechanically robust.
- Prismatic/cylindrical: more rigid and mechanically robust.
Practical design guidance
- Start from vehicle requirements: range (Ah) and peak motor current → choose pack voltage and Ah.
- Select cell chemistry and form factor to meet peak/pulse currents, cycle life, and cost targets.
- Use BMS and embedded systems to monitor SOC/SOH, enforce protections, and record cycles.
- Ensure charger and onboard/offboard architecture matches vehicle inlet (CCS2 conventions when applicable).
- Respect datasheet limits for power, temperatures, storage, and transport.
Course logistics & next steps
- Upcoming sessions will focus on embedded systems for EVs (MCU/BMS/VCU, motor control).
- Offline hands-on labs start Feb 16 (Belgavi and Nagarbavi): battery assembly, harness work, motor teardown and winding, full vehicle hands-on work.
- Students were asked to prepare notes on CCS2 and socket types and bring questions.
Speakers / sources referenced
- Instructor / presenter: VisionAstraa EV Academy facilitator (unnamed).
- Participants / students (no individual names recorded).
- Datasheet / cell brands mentioned as examples: Highstar (search example), Panasonic, LG.
- Connector / standards referenced: CCS2, Type 2 socket, Type 6 / Type 7, Chori connector, Anderson connector, DT connector.
- Technologies / components referenced: BMS, MCU, VCU, motor controller, MOSFETs, onboard charger, offboard charger.
Category
Educational
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