Why Are Lithium Batteries Restricted on Airplanes?

You need to transport your drone batteries for a mission, but the rules are confusing. A mistake could get your high-value equipment confiscated, delaying your entire project and costing you money.

Lithium batteries¹ are restricted due to the risk of thermal runaway²—a violent, uncontrollable fire that is nearly impossible to extinguish in an airplane's cargo hold. The rules are designed to keep batteries in the cabin where a fire can be quickly addressed.

As a battery manufacturer shipping globally, we navigate these regulations every single day. The restrictions aren't arbitrary; they are based on the unique and potentially dangerous chemistry of lithium batteries. To understand the rules, you first have to understand the specific risk that airlines and safety regulators are trying to prevent. It all comes down to a single, dangerous phenomenon.

What Is Thermal Runaway and Why Is It So Dangerous in the Air?

The term 'thermal runaway' sounds technical and distant. But not understanding this core risk is why people make dangerous mistakes when packing batteries for a flight, putting everyone in jeopardy.

Thermal runaway is a violent chain reaction where a damaged or short-circuited battery generates intense heat, causing a fire or explosion. In a cargo hold, this event is undetectable until it's too late, and standard fire suppression systems are ineffective against a lithium battery fire.

This isn't a normal fire. A short circuit, physical damage from being crushed in a suitcase, or an internal defect can cause one cell to overheat. This heat triggers a chemical reaction that generates even more heat, which then spreads to the next cell. The process escalates exponentially within seconds, venting flammable, toxic gases and often leading to an explosion. The regulations are built around a simple principle: if a fire happens, it must happen where it can be seen and fought.

The Critical Difference: Cargo vs. Cabin

Location	Detection	Intervention	Risk Level
Cargo Hold	Slow (smoke detectors)	Automated (Halon gas, ineffective on Li-ion fires)	Catastrophic
Cabin	Immediate (sight/smell)	Manual (Flight crew with specialized extinguishers)	Manageable

This is why the rules are so strict about keeping batteries out of the cargo hold. A fire in a passenger's bag in the cabin is a serious incident, but it's one the crew is trained to handle. A fire in the cargo hold is an emergency with a much lower chance of a successful outcome.

So, Are Drone Batteries Banned from Planes Entirely?

With such serious risks, it's easy to assume all drone batteries are banned. This confusion causes professionals to leave critical equipment behind, unnecessarily limiting their operational capability on remote jobs.

No, they are not banned, but they are strictly regulated. The number one rule is that all spare lithium batteries—including drone batteries and power banks—must be in your carry-on luggage³. They are completely forbidden from checked bags to keep the fire risk in the cabin.

The regulations, set by bodies like the IATA⁴, are actually quite clear once you understand the logic. They focus on the amount of energy stored in the battery, measured in Watt-hours (Wh). For any procurement manager or operator, understanding these thresholds is non-negotiable for travel.

Understanding the Watt-hour (Wh) Limits

To find your battery's Wh rating, use this formula: Voltage (V) x Amp-hours (Ah) = Watt-hours (Wh). For a 20,000mAh battery, that's 20Ah.

Watt-hour (Wh) Rating	Rule	Example
Under 100Wh	Allowed in carry-on. No airline pre-approval needed.	Most standard laptop, phone, and many consumer drone batteries.
100Wh to 160Wh	Allowed in carry-on, but airline approval5 is required. Usually limited to two spare batteries per person.	High-capacity batteries for professional camera or large industrial drones.
Over 160Wh	Forbidden for passenger transport without special exemptions (e.g., mobility devices).	Very large industrial power packs or custom-built batteries.

Always check your specific airline's policy before you fly, as they can have slightly different rules.

How Should You Pack Drone Batteries for a Flight?

Knowing the rules is half the battle; packing correctly is the other half. Simply tossing batteries in your bag is a recipe for a short circuit or having them confiscated at security.

The primary goal is to prevent short circuits by protecting the battery terminals. Use the original packaging, put electrical tape over the contacts, or place each battery in a separate plastic or LiPo-safe bag. Never let them be loose in your carry-on.

A short circuit is the most common trigger for thermal runaway. If a battery's metal terminals touch keys, coins, or another battery's terminals inside your bag, it can create a circuit, causing a rapid discharge and dangerous overheating. Proper packing is a simple but critical safety step that security personnel will be looking for.

Pre-Flight Battery Checklist:

• Calculate Wh: Know the Watt-hour rating of every battery you're carrying. If it's not printed on the label, have the specs ready.
• Protect Terminals: Ensure every spare battery's terminals are covered. Electrical tape is a simple and effective solution.
• Isolate Each Battery: Place each battery in its own plastic bag, its original box, or a dedicated LiPo-safe bag. This prevents them from bumping into each other.
• Carry-On Only: Triple-check that all spare batteries and power banks are in your carry-on bag, not your checked luggage.
• Check Airline Rules: A quick search on the airline's website for "lithium batteries" will give you their specific policies, especially for batteries over 100Wh.

Conclusion

Lithium batteries are restricted on planes due to fire risk. Always pack them in your carry-on, protect the terminals, and verify the Watt-hour limits with your airline for safe travel.

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