(EU) 2023/1542 · Annex XIII(1)(p)
C-rate of the cycle-life test: data about a test, not about a battery
This field does not describe the battery; it describes a test. Point 1(p) of Annex XIII requires the c-rate of the relevant cycle-life test — that is, the condition under which a different value was measured. The word “relevant” is the key: it is the same test you name under point 1(j). If the two numbers refer to different tests, the passport contradicts itself. And because the term is used once in the Regulation and never defined, it is your test report that must explain it, not the Regulation.
“Relevant” means the same test as in point 1(j)
Point 1(j) of Annex XIII requires the expected battery lifetime in cycles and the reference test used. Point 1(p) requires the c-rate of that test. Both fields are public and sit in the same list, so a reader takes them together. If the cycle count comes from the cell supplier's test while the c-rate comes from your pack test, both fields are formally complete and substantively inconsistent — a mismatch anyone reading the two numbers in sequence will see.
One number for two rates
Point 1 of Part B of Annex IV lists the applied discharge rate and charge rate among the elements explaining the measurements — that is two of them. If they differ in your test, a single c-rate does not describe it. Together with point 3 of Part B, which requires the depth of discharge in the cycle-life test, it is clear that the value in this field is an entry point into the description of conditions, not the description itself. State which rate it refers to.
A public number from a non-public source
The value belongs to point 1 of Annex XIII and is accessible to everyone. The results of test reports, however, are reserved by point 3 of the same Annex to notified bodies, market surveillance authorities and the Commission. This is not a contradiction but a division: you publish the condition, the report stays with the authorities and in the technical documentation. The practical consequence is that nobody can check the public number without you — which is exactly why it must be transcribed from the report, not estimated.
Where it goes wrong
- A c-rate from a cell test alongside a cycle count measured on the pack, or the reverse.
- A single value when the charge and discharge rates in the test differed.
- A value estimated from a catalogue because no test report was ever commissioned — the field describes a test, and without a test it has no source.
- Publishing an extract of the test report next to the value; under point 3 of Annex XIII report results are not public.
Frequently asked
Does the Regulation define c-rate?
No. The term appears only in point 1(p) of Annex XIII. Its meaning has to come from your test report and from the elements in Part B of Annex IV.
Which test is the “relevant” one?
The one you named as the reference test under point 1(j) of Annex XIII. Both fields must describe the same measurement.
May I use the c-rate from my cell supplier's test?
Only if that is the test your cycle-life figure also rests on. Otherwise you are describing someone else's test on someone else's test unit.
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