🔋✈️ Can I fly with this battery?

• Spare packs go in your carry-on. Never in checked baggage. Not sometimes — never.
• Under 100 Wh: fine in carry-on, no permission needed.
• 100–160 Wh: you need the airline's approval, and a maximum of two spares.
• Over 160 Wh: not allowed on a passenger aircraft at all, either cabin or hold.

1. Spares never go in the hold

A "spare" is any pack not installed in a device — which is almost every RC pack you own, because we carry them loose. The FAA is explicit: "Spare (uninstalled) lithium ion and lithium metal batteries, including power banks and cell phone battery charging cases, must be carried in carry-on baggage only."

2. The gate-check trap

This is the one that catches people out. If your carry-on gets taken at the gate or at planeside — which happens constantly on full flights and small aircraft — you must take every pack out and keep them with you in the cabin. Handing the bag over with packs inside turns a legal carry-on into an illegal checked bag.

3. Protect the terminals

Terminals must be protected against short circuit. In practice: tape over bare bullets, caps on XT60/XT90/EC5, each pack in its own bag or a LiPo-safe pouch, and nothing metal loose in the same pocket. A shorted pack in an overhead locker is the exact event these rules exist to prevent. LiPo-safe bag^ⓘA fire-resistant fibreglass bag or metal container used to charge and store LiPo packs so that a failing cell is contained.A bag is containment, not permission: charge on a non-flammable surface, clear of anything that burns, and stay in the room and awake for the whole charge.More → is the easy version.

4. If the pack prints a Wh number, that number wins

Some packs are labelled in watt-hours already. Use the printed figure — it is what a gate agent will read, and it settles any argument about nominal voltage.