(EU) 2023/1542 · Annex XIII(1)(g)
Rated capacity in ampere-hours: the same number in four places
This looks like the easiest field in the passport, but it is in fact the most common source of internal contradiction. The same physical quantity appears in four places in the regulation, each time in a slightly different form — and because companies fill them in at different times from different sources, the numbers drift apart.
Four places, one quantity
Point 1(g) of Annex XIII requires rated capacity in ampere-hours. Point 6 of Part A of Annex VI requires “capacity” as label content. Part A of Annex IV requires rated capacity together with capacity fade in per cent. And for rechargeable portable, LMT and SLI batteries, Article 13(2) requires a separate capacity label. All of these must derive from the same measurement.
The unit is not optional
Annex XIII explicitly requires Ah. Datasheets often quote kWh or Wh because it is more meaningful to a buyer. The conversion is only superficially simple: kWh is Ah multiplied by nominal voltage, so the voltage must come from the same measurement too. If Ah, V and kWh do not reconcile, you have a contradiction in your documentation that anyone with a calculator can find.
Rated capacity is not declared capacity
Annex IV defines rated capacity as the total number of ampere-hours that can be withdrawn from a fully charged battery under reference conditions. A cell catalogue figure measured at a different temperature or discharge rate is not the same number — and at pack level it is not a simple sum of the cells.
Where it goes wrong
- Ah from the cell datasheet and kWh from the pack specification that do not reconcile with nominal voltage.
- Stating only kWh when Annex XIII requires ampere-hours.
- Using a declared catalogue capacity instead of the value under reference conditions.
- Different values on the label, in the passport and in the technical documentation because they were produced at different times.
Frequently asked
In which unit must rated capacity be stated?
In ampere-hours. Point 1(g) of Annex XIII states this explicitly.
Can I state kWh instead of Ah?
Not as a substitute. You may add kWh, but the field requires Ah — and both figures must reconcile with the nominal voltage.
Is the cell supplier's datasheet value enough?
Only if it relates to the battery as placed on the market and was measured under the reference conditions in Annex IV. Pack capacity is not a simple sum of cell capacities.
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