How many spare, rechargeable, lithium-ion batteries may passengers transport in their carry on baggage?

• A. Not more than two
• B. Not more than four
• C. Any number
• D. Only one

Answer: (A)

Spare lithium-ion batteries are allowed in carry-on due to safety concerns, but there is a strict limit on how many you can bring. The maximum number per passenger is two. Each spare battery must be protected against short circuits (terminals insulated or kept in original packaging or a separate bag) to prevent accidental ignition, and batteries should be carried in carry-on rather than checked baggage.

Two is the limit because it balances practicality—you may need spares for multiple devices—with safety. Carrying more than two would exceed the allowable limit, while options suggesting only one or unlimited numbers don’t meet the standard rule.