DIN EN 61951-1:2017-12

This standard specifies the marking, designation, dimensions, tests and requirements for sealed nickel-cadmium small prismatic, cylindrical and button rechargeable single cells and batteries, suitable for use in any orientation, for portable applications. Contrary to NiMH and lithium based secondary cells, NiCd cells have a high level of robustness against deep discharge and overcharge. This way, a uniform state of charge can be achieved in a battery of series connected NiCd secondary cells by deliberately overcharging them with a low current (one tenth of the capacity per hour). Cells with an already high level of charge convert supplied energy into heat, if the energy is sufficiently low, without suffering irreversible damage in the process. This procedure is not, or only to a limited extent, applicable to other types of secondary cells, leading to a significantly higher amount of damages due to a non-uniform state of charge of the cells (and resulting overcharge or deep discharge conditions). In addition, NiCd cells have favourable characteristics when used at low ambient temperatures. Both characteristics are of particular importance for many safety critical applications so that in many cases, lithium or NiMH secondary cells are not suitable for use. The responsible committee is DKE/K 371 "Akkumulatoren" ("Secondary cells and batteries") of the DKE (German Commission for Electrical, Electronic and Information Technologies) at DIN and VDE.