Battery capacity, expressed in kilowatt-hours (kWh), measures the electrical energy a battery can store and deliver over time.
It corresponds to the amount of energy used when a device with a power of one kilowatt operates for one hour. In the field of electric mobility, kWh is used to assess a vehicle’s range: the higher the capacity, the more kilometres the vehicle can travel before needing a recharge. For example, a heavy-duty vehicle consuming 1.2 kWh/km could travel about 500 km with a 600 kWh battery. It’s important to distinguish between gross capacity (total energy storable) and usable capacity (energy actually available for driving), which is generally lower to preserve battery life and avoid extreme charge/discharge cycles.
Note: kWh measures a quantity of energy, whereas kW expresses instantaneous power, differentiating the battery’s storage capacity (kWh) from its charging speed (kW).