US DOT Hazmat Safety Rule to Place Limits on Lithium Batteries Carried by Passengers Aboard Aircraft Effective January 1, 2008 [open pdf - 106KB]
This press release details new restrictions imposed on lithium batteries placed in carry on baggage aboard aircraft: "Passengers will no longer be able to pack loose lithium batteries in checked luggage beginning January 1, 2008, once new federal safety rules take effect. The new regulation, designed to reduce the risk of lithium battery fires, will continue to allow lithium batteries in checked baggage if they are installed in electronic devices, or in carry-on baggage if properly protected from short circuiting in their original packaging or by placing them in individual plastic bags or a protective travel case. Common consumer electronics such as digital cameras, cell phones, and most notebook computers are still allowed in carry-on and checked luggage. Moreover, any number of spare batteries for these devices will be allowed in carry-on baggage if they are properly protected from short circuiting and do not exceed 8 grams (~100 watt hours) of equivalent lithium content. Most lithium-ion cell phone and standard notebook computer batteries are below 8 grams (~100 watt hours) of equivalent lithium content. Batteries not installed in electronic devices are not permitted in checked baggage."
U.S. Department of Transportation: Pipeline and Hazardous Materials Safety Administration: http://phmsa.dot.gov/portal/site/PHMSA