ANSI C18.2M: Portable Rechargeable Batteries Specifications

Woman's hand holding a ANSI C18.2M battery smartphone above computer

A rechargeable battery is an electronic device’s heart, and, while they don’t pump anything, batteries supply laptops, smart phones, and other electronics with their electric life force. The majority of batteries utilized for portable devices are lithium-ion, a technology so important to modern life that the 2019 Nobel Prize in Chemistry was awarded to three of its pioneers. Common alternatives to lithium-ion include nickel-cadmium and nickel-metal hydride rechargeable cells and batteries.

As prolific and reachable products, portable rechargeable cells and batteries benefit from the clear identification of standard specifications and guidance. ANSI C18.2M provides just this.

ANSI C18.2M consists of two parts: ANSI C18.2M Part 1-2019: Portable Rechargeable Cells and Batteries – General and Specifications and ANSI C18.2M Pt 2-2021: Portable rechargeable cells and batteries – Safety standard.

General Specifications for Rechargeable Batteries

The rechargeable batteries of electronic devices, as products that are almost universal while being fabricated by, and installed within devices manufactured by, an assortment of companies, are practically the ideal products for standardization. Assuring uniform guidelines for harmonization among different manufacturers and designers allows these batteries to perform reliably, without any surprises or confusion for the producers or consumers.

ANSI C18.2M Part 1-2019 aids with this issue substantially, as it assures the electrical and physical interchangeability of rechargeable battery products from different manufacturers and minimizes proliferation of cell and battery types by defining standard performance tests and providing guidance to consumers, manufacturers, designers, and other end users.

The ANSI C18.2M Part 1-2019 publication is applicable to portable rechargeable, or secondary cells and batteries based on nickel-cadmium, nickel-metal hydride, and lithium-ion (including lithium ion polymer) electrochemical systems. It addresses battery dimensions, terminals, a standard charge method, polarity, and test conditions and procedures.

Furthermore, the standard specifies designations for secondary batteries, stating that they be designated by a number, followed by a letter, followed by a sequential number. The first number designates the nominal voltage of the battery, and the letter—H (nickel-metal hydride), I (lithium-ion including lithium ion polymer), or K (nickel-cadmium)—designates the electrochemical system. The number that follows is sequentially assigned according to physical dimensions, terminal configurations, and performance variables.

For example, in accordance with ANSI C18.2M Part 1-2019, four nickel-cadmium cells would be designated as 4.8K27.

Safety Standard for Portable Rechargeable Batteries

The technology driving the success of rechargeable batteries is not flawless. Lithium-ion batteries, in addition to degrading as soon as they leave the factory, are extremely sensitive to high temperatures, and even can burst into flame in the event of failure.

Since these batteries are in the pockets of everyday consumers or otherwise in their presence at any given moment, assuring their safe use is of prime concern. The second part of ANSI C18.2M, ANSI C18.2M Pt 2-2021, focuses specifically on safety, detailing guidelines for standardized portable lithium-ion, nickel-cadmium, and nickel-metal hydride rechargeable cells and batteries to ensure their safe operation under normal use and reasonably foreseeable misuse. It includes information relevant to hazard avoidance.

For each of these battery types, ANSI C18.2M Pt 2-2021 specifies tests for altitude, thermal shock, vibration, mechanical shock, external short-circuit, forced discharge, overcharge, free fall, impact-cells, crush-cells, crush-batteries, thermal abuse, and mold stress. It also addresses acceptance criteria for venting, rupture, and other considerations.

Both ANSI C18.2M standards are developed and published by the National Electrical Manufacturers Association (NEMA) and processed and approved for submittal to ANSI by the American National Standards Committee C18 on Portable Cells and Batteries.

ANSI C18.2M Part 1-2019: Portable Rechargeable Cells and Batteries – General and Specifications and ANSI C18.2M Pt 2-2021: Portable rechargeable cells and batteries – Safety standard are available on the ANSI Webstore.

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