These definitions are provided for use with Safe Travel.

Carry-on baggage. Baggage carried onboard the plane, typically stowed in the overhead bin or beneath the seat.

Checked baggage. Large baggage given to the airline prior to boarding the plane, to be checked as stowage.

Equivalent Lithium Content (ELC). ELC is a measure by which lithium ion batteries are classified.

• 8 grams of ELC are equal to about 100 watt-hours.
• 13 grams of ELC are equal to about 160 watt-hours.

You can arrive at the number of watt-hours your battery provides if you know how many milliamp hours and volts your battery provides:
mAh/1000 x V = Wh

Most lithium ion batteries marketed to consumers are below 100 watt-hours (8 grams ELC). If you are unsure of the watt-hour rating of your lithium ion battery, contact the manufacturer.

Larger Lithium Ion Batteries exceed a watt-hour rating of 100 watt-hour but do not exceed 160 watt-hour. Some very large after-market laptop computer batteries, and some batteries used for professional audio-visual application, fall within this definition. Approval of the operator is required.

Larger Lithium Metal Batteries contain more than two grams of lithium, and are forbidden in air travel. (No common consumer lithium metal batteries are in the "larger" category).

Lithium Batteries. When you see this term alone on SafeTravel pages, it refers to both lithium ion batteries and lithium metal batteries. Lithium polymer batteries are a type of lithium ion battery, and are included in this term.

Lithium Ion Batteries. These are rechargeable lithium batteries, similar to those found in cameras, cell phones, laptop computers, and radio-controlled toys. Lithium polymer batteries are those types of lithium ion batteries.

Lithium Metal Batteries. These cannot be recharged and are designed to be discarded once their initial charge is used up.

Smaller Lithium Ion Batteries contain up to 100 watt-hours. Cell phone batteries and most laptop computer batteries fall below the 8 gram threshold. Lithium Ion Batteries with more than 160 watt-hours are forbidden in air travel.

Spare Batteries. Spare batteries, also called "loose" batteries, are those not installed in equipment. A lithium ion battery inside your laptop computer is an installed battery. A battery carried separately, in case that installed battery runs low, is a spare battery.

Watt-hour. For the purposes of this page, the watt-hour serves as an indirect measure of Equivalent Lithium Content (ELC). 8 grams ELC are about equal to 100 watt-hours.