MOC-3 §7.(a)(3)(ii) defines worst case relative to a specific response: the combination of test conditions that maximizes the potential for cell-to-cell propagation at battery system level. The response being maximized is propagation, which is distinct from maximum thermal energy release or maximum gas generation — a cell that produces the most energetic runaway at a given SOC may not produce the highest propagation risk at that SOC if most energy is expelled rather than conducted to neighbors.
This distinction matters for DVP construction because the four characterization dimensions — trigger method, SOC, heater position, heating rate — interact. The CRD states explicitly that considering these variables in isolation is insufficient. The worst-case combination must be found empirically across the matrix, not assumed from any single-variable sweep.
The characterization record serves a specific structural function in the MOC-3 evidence chain: it is what justifies using a single-cell trigger for system-level non-propagation testing. EASA's CRD ties the two directly. An incomplete worst-case determination undermines the basis for the single-cell approach, which means the system-level test design is unsupported.
Four mandatory dimensions (§7.(a)(3)(ii)(A)–(D)):
- Trigger method (overcharge vs. overheat produce different failure modes)
- SOC (competing effects: low SOC = more unreacted material; high SOC = more energetic event)
- Heater position relative to vent (can force side/bottom rupture)
- Heating rate (5–20°C/min; affects flame vs. smoke behavior)
Population coverage (§7.(a)(3)(iv)):
- Replicates from different lots, manufacturing dates, and sites
- Replicate count agreed with EASA before testing
- Single-lot, single-date samples do not satisfy the requirement
Seven mandatory measurements (§7.(a)(3)(iii)):
- Initial SOC, trigger time, max temperature, average total thermal energy (J), initiation temperature, temperature rise rate, mass ejected
Pre-trigger condition: Stabilize at 55°C or max operating temperature, whichever is higher (§7.(a)(3)(xi))
Monitoring: Minimum 8 hours post-trigger (§7.(a)(3)(xv))
Source: MOC-3 SC-VTOL Issue 2, 21 June 2023. Tier 1 — full text inspected. Last verified 2026-08-26.