Battery & EV Systems

Battery & EV Systems (battery-ev-systems)

Purpose

Screen battery pack nominal energy, ohmic heat generation, required cooling flow, minimum busbar cross-section, and simple vent area for EV and stationary storage packs at concept design stage.

Physics & theory

Pack configuration: $N_s$ series × $N_p$ parallel cells. Nominal voltage $V_{\mathrm{pack}}=N_s{V}_{\mathrm{cell}}$; energy $E=V_{\mathrm{pack}}{N}_p{C}_{\mathrm{Ah}}$ (Wh). Cell heating from internal resistance: $P=N_{\mathrm{total}}{I}_{\mathrm{cell}}^2{R}_{\mathrm{cell}}$ with $I_{\mathrm{cell}}=I_{\mathrm{pack}}/N_p$.

Coolant mass flow $\dot{m}=P/(c_p\Delta T_{\mathrm{allow}})$ removes heat at allowable temperature rise. Busbar area from current density limit $A_{\mathrm{bar}}=I/j_{\mathrm{allow}}$. Vent area from volumetric gas flow and target velocity during abuse scenario — first-pass screen only.

Advanced systems calculators use lumped-parameter screening models suitable for concept trade studies. Each calculator returns explicit assumptions and warnings arrays documenting model limits. Constants such as ( sigma ) (Stefan–Boltzmann), ( mu_0 ), and ( R ) (gas constant) use SI definitions from the solver source.

Results are not certified for regulatory submission without independent verification against detailed analysis or test data.

Governing equations

Numerical method

Closed-form pack electrical and thermal screening (advanced-systems/calculators). Vent area from gas generation rate / target velocity — not full thermal runaway simulation.

Inputs

Outputs

• Pack voltage, energy (kWh), heat generation (W), cooling mass flow, busbar area (mm²), vent area (m²).

Design codes & checks

• Indicative: Pack energy, heat, vent screening
• ISO: ISO 6469 electric road vehicle safety (context)
• UL: UL 2580 battery safety (context)
• SAE: SAE J2464 abuse testing (context)

Assumptions & limitations

• Uniform cell parameters; no cell-to-cell imbalance or BMS logic.
• $I^{2}R$ heating only; no entropic heat or reaction heat during abuse.
• Vent sizing is volumetric screen — not regulatory compliance tool.
• No propagation, enclosure rupture, or state-of-charge maps.

References

1. Plett, G. L. Battery Management Systems, Vol. I & II. Artech House.
2. ISO 6469-1:2019. Electrically propelled road vehicles — Safety specifications.
3. UL 2580. Batteries for Use in Electric Vehicles.
4. SAE J2464. Electric and Hybrid Electric Vehicle Rechargeable Energy Storage System Safety.
5. PhyCalcPro verification benchmarks in src/data/verification/ where available for this module.
6. Beer, F. P., et al. Mechanics of Materials, 8th ed. McGraw-Hill — foundational stress and deformation theory.