Setting SOC¶
The standard's default is "highest working SOC" — i.e., the worst case for energy released. Tests that need a different SOC say so explicitly. The thermal-propagation test (Appendix C) tightens this to ≥ 95 % or ≥ 90 % depending on charging mode.
Default test SOC (6.1.10)¶
Unless otherwise specified, the test object should be tested at the highest working state-of-charge (SOC) as specified by the manufacturer.
Source: clause 6.1.10.
Engineering note (non-normative): "highest working SOC" is the manufacturer's stated 100 % indication, not the chemical limit. For LFP packs commonly capped at ~3.45 V/cell, that is the published full-charge state, not the 3.65 V hard limit.
SOC adjustment method (6.1.7)¶
When a test specifies a target SOC of n %, follow this method (or the manufacturer's equivalent):
The method for adjusting SOC to the test target value n%: Fully charge the battery cell, battery pack, or system according to the charging method provided by the manufacturer, let it stand for 1 hour, and discharge at a constant current of I₃ for a time t, calculated using formula (1), or use the method provided by the manufacturer to adjust the SOC. After each SOC adjustment, the test object should stand for 30 minutes before the new test begins, or as per the conditions specified by the manufacturer.
Discharge time:
Where t is the discharge time at constant I₃, and n is the target SOC percentage.
| Target SOC | t at I₃ |
|---|---|
| 100 % | 0 h |
| 80 % | 0.6 h (36 min) |
| 50 % | 1.5 h |
| 20 % | 2.4 h (144 min) |
After SOC adjustment, stand 30 min before the new test (or per the manufacturer's instruction).
Source: clause 6.1.7.
SOC for thermal propagation (Appendix C.5.2 b)¶
The thermal-propagation test requires a higher SOC than the default for some charging architectures:
Before the test begins, adjust the SOC of the test object. For battery packs or systems designed for external charging, the SOC should be adjusted to no less than 95% of the manufacturer's specified maximum working state; for battery packs or systems designed to be charged solely via the vehicle's energy, the SOC should be adjusted to no less than 90% of the manufacturer's specified maximum working state.
| Charging architecture | Minimum SOC for thermal propagation test |
|---|---|
| Externally chargeable (BEV, PHEV) | ≥ 95 % of max working SOC |
| Vehicle-charged only (HEV) | ≥ 90 % of max working SOC |
See thermal propagation for the full test conditions.
Source: clause C.5.2 b.
Cross-reference: tests that override the default SOC¶
| Test | SOC requirement | Clause |
|---|---|---|
| Over-discharge (cell) | Adjust to discharge-termination voltage | 8.1.2.2 |
| Safety after fast-charge cycles | 20 % – 80 % cycling, then 8.1.4 | 8.1.8.2 |
| Over-current protection (system) | "Mid-SOC" | 8.2.12 |
| Over-discharge protection (system) | "Lower-SOC" start | 8.2.15 |
| Thermal propagation | ≥ 95 % or ≥ 90 % | C.5.2 b |
All other tests use the default highest working SOC.
Source¶
Clauses 6.1.7, 6.1.10, C.5.2 b (PDF pages 13, 35).