IEC 61951-2:2011 specifies marking, designation, dimensions, tests and requirements for portable sealed nickel-metal hydride, small prismatic, cylindrical and button rechargeable single cells, suitable for use in any orientation. This third edition cancels and replaces the second edition published in 2003 of which it constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: - clause 4: addition of 2 parameters; - clause 5: addition of cells type "S" and cells type "T"; - subclause 6.1.2: addition of new cylindrical cells; - subclause 7.8: addition of a specific test for "S" cells.