Electronic Design

Transportation Guidelines For Lithium Batteries Get Updated

Most people involved in the design and manufacture of portable devices have heard that there are significant restrictions and in-depth testing associated with the shipment of lithium-based battery packs. However, the details of the regulations are obscure and confusing.

Recently, the U.S. Department of Transportation’s (DOT) Pipeline and Hazardous Materials Safety Administration (PHMSA) published significant changes to United States policy. This ruling harmonizes the U.S. policy with international law, eliminating some confusion. Yet the policies are currently in flux, so the interpretation is somewhat more complicated.

The lithium-battery final rule was published on August 9, 2007 in the Federal Register. This long-awaited rule reconciles the U.S. lithium-battery hazardous materials regulations (HMR) with the regulations that have been in effect internationally since 2003.

Substantial regulatory and formatting changes to the lithium-metal (primary) and lithium-ion (Li-ion) battery provisions were unveiled with an effective date of the rule of January 1, 2008. However, some of the special provisions will go into effect in 2009. Therefore, those involved in the design of battery packs that will be produced in the interim must be particularly cognizant of the details of the ruling.

What’s New

Eventually, almost all lithium primary and lithium-ion (Li-ion) battery packs will need to be tested according to the United Nations (UN) manual of Tests and Criteria prior to their production shipments. Yet one of the more significant issues addressed in the DOT’s rule is confirmation that single-cell lithium-battery packs do not require UN testing provided that the cell was previously tested and passed the UN testing as outlined in the Manual for Tests and Criteria.

The DOT’s rule defines three categories of batteries based on their “size” or Equivalent Lithium Content (ELC). ELC is calculated in grams, on a per cell basis, to be 0.3 times the rated capacity in ampere hours. But starting January 1, 2009, for international shipments by air or by sea, the determination is changing to a method of watt hours (see the table).

Watt hours are defined as the rated capacity multiplied by the nominal voltage. The new exception limits will be set at 20 watt hours for cells instead of 1.5 g ELC and 100 watt hours for battery packs instead of 8 g ELC. The watt-hour rating must be placed on the label of excepted battery packs (no more than 100 watt hours) so it can be seen by users of the product. Even after January 1, 2009, designers still will be required to use the ELC method to determine the size of lithium batteries that will be shipped by ground or by rail in the U.S.

“Small” lithium-battery packs that have passed the UN testing requirements, including batteries packed with or installed in equipment, can be transported “non-restricted.” That is, the batteries do not have to be shipped as fully regulated Class 9 hazardous materials. The actual requirement for testing small battery packs does not go into effect and become mandatory until October 1, 2009.

“Medium” lithium-battery packs that have passed the UN testing requirements, including batteries packed with or installed in equipment, can be transported non-restricted by motor vehicle or rail only. Lithium batteries that will be transported by passenger or cargo aircraft must be shipped as fully regulated Class 9 hazardous materials.

“Large” lithium-battery packs that have passed the UN testing requirements, including batteries packed with or installed in equipment, must be shipped as fully regulated Class 9 hazardous materials.

Still Need More Information?

These changes to the U.S. DOT regulations conform significantly better with the international restrictions previously set forth. But it is also obvious, from the number of caveats and exceptions that I’ve needed to include here, that the new ruling is far from transparent.

There are several good sources for information on the shipping rules. For example, the Portable Rechargeable Battery Association (www.prba.org) is a great resource. If you can’t find a good, direct answer to your question, write to [email protected] We will post the best and most common questions with their answers online.

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