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Charging procedure

Most cell- and pack-level tests start from a fully charged state. The standard defers to the manufacturer's method when one is provided; otherwise a CC-CV fallback applies for cells. The 1-hour stand after each charge or discharge is mandatory.

Symbols (4.1)

I₁: 1-hour rate discharge current (A), its value equals the rated capacity value. I₃: 3-hour rate discharge current (A), its value equals one-third of the rated capacity value.

Symbol Definition Value
I₁ 1-hour rate current numerically equal to rated capacity (A)
I₃ 3-hour rate current one-third of rated capacity (A)

Example: a cell with rated capacity 60 Ah has I₁ = 60 A and I₃ = 20 A.

Source: clause 4.1.

Cell standard charging (7.1.1)

The procedure has three steps: discharge to the manufacturer's discharge-termination voltage, stand 1 h, then charge per the manufacturer's method and stand 1 h again.

Discharge with a current not less than I₃ as specified by the manufacturer until the discharge termination voltage defined by the manufacturer is reached. Let it stand for 1 hour (or a standing time not exceeding 1 hour as provided by the manufacturer), then charge according to the method provided by the manufacturer. After charging, let it stand for 1 hour (or a standing time not exceeding 1 hour as provided by the manufacturer).

Fallback (no manufacturer charging method)

Charge with a current not less than I₃ as specified by the manufacturer using constant current until the charging termination voltage defined by the manufacturer is reached, then switch to constant voltage charging. Stop charging when the charging current decreases to 0.05 I₁, and let it stand for 1 hour (or a standing time not exceeding 1 hour as provided by the manufacturer).

Summary of the fallback:

  1. CC at ≥ I₃ until charging-termination voltage.
  2. Switch to CV.
  3. Stop when current drops to 0.05 I₁.
  4. Stand 1 h.

Source: clause 7.1.1.

Pack/system charging (7.2)

For pack/system pre-treatment (7.2.2.1) the same logic applies — charge per the manufacturer's recommended method, or with a current not less than I₃, until the manufacturer-specified charging-termination condition is reached, then stand 30 min (or per manufacturer). The pack-level standard does not specify a CC-CV fallback at pack level; the manufacturer's method governs.

A supplementary charge (7.2.2.3) is required if more than 24 h elapses between the end of pre-treatment and the start of a new test — see pre-treatment cycles.

Source: clauses 7.2.2.1 a, 7.2.2.3.

Where this is invoked

Every cell test in 8.1.x calls 7.1.1 explicitly:

Pack tests start from the highest working SOC after pre-treatment — see setting SOC.

Source

Clauses 4.1, 7.1.1, 7.2.2.1 (PDF pages 13–14).