E DIN EN 61951-1/A1 VDE 0510-53/A1:2022-08

This standard specifies the marking, the designation, the dimensions, the tests and the requirements for portable, small, rechargeable, gas-tight nickel-cadmium single cells in prismatic or cylindrical design or in the form of button cells, which can be used in any position of use.
In contrast to NiMH and lithium-based accumulators, NiCd cells are characterized above all by their significantly greater robustness against deep discharge and overcharging. In a battery of NiCd accumulators connected in series, a uniform state of charge can be achieved by specifically overcharging it with low current (1/10 of the capacity per hour). Cells with an already high charge level convert the supplied energy into heat at sufficiently low currents without suffering irreversible damage. This procedure is not possible or only possible to a limited extent with other battery types, so that damage occurs more frequently due to an uneven charge state of the cells (and the resulting overcharging or deep discharge). Furthermore, NiCd cells have favorable properties when used at low ambient temperatures.
Both properties are of great importance, especially in many safety-critical applications, so that in many cases lithium or NiMH batteries do not offer a suitable replacement.