Why Are Lithium Batteries Not Allowed in Flights?

Ever wonder how batteries aren’t allowed on flights? Why isn’t your checked luggage allowed to have lithium batteries?

Look around you, and Lithium batteries are powering goods today, from children’s toys and e-bikes down to everyday items near you.

Yet, when it comes to flying, authorities closely monitor and regulate batteries—especially lithium ones.

Why are batteries hazardous cargo for aviation? How do they work, and more importantly, why are lithium batteries of particular concern? This article examines such questions in an attempt to discuss incidents, regulations, and the future concerning sky battery safety.

How Do Batteries Work?

A battery is essentially a storage unit for energy, converting chemical energy into electrical energy through electrochemical reactions. The constituents of a battery are:

• Anode (Negative Terminal): Releases electrons during discharge.
• Cathode (Positive Terminal): Accepts electrons during discharge.
• Electrolyte: Facilitates the movement of ions between the anode and cathode.

Different batteries use various materials for these components, which influences their energy density, safety, and applications.

Types of Batteries and Their Common Uses

Here’s a quick overview of popular battery types:

In aviation, we are more concerned with lithium-ion and lithium-metal batteries. So, what’s the difference between them?

What’s the Difference Between Lithium-Ion and Lithium-Metal Batteries?

Primary vs Secondary Batteries:

Batteries are generally classified as primary (non-rechargeable) or secondary (rechargeable). Primary batteries are used once, discarded and replaced, while secondary batteries can be recharged multiple times.

Lithium-metal batteries are primary batteries, I’m listing a few items that commonly contain these batteries and are relevant for a passenger or an air traveller:

• Key fobs and remote controls
• Wristwatches
• Medical devices like glucose monitors or pacemaker accessories
• Small toys or some game controllers

Lithium-ion batteries are secondary batteries. Some passengers-related items are:

• Smartphones, tablets, and laptops
• Portable power banks and chargers
• Wireless headphones and earbuds
• E-cigarettes and vaping devices
• Digital cameras and camcorders

Lithium-metal batteries are prohibited as cargo on passenger flights due to their higher fire risk.

Why Are Lithium Batteries a Concern in Aviation?

Although most batteries are harmless if used and maintained correctly, lithium-ion and lithium-metal batteries pose significant risks in aviation. These batteries are classified as dangerous goods due to their specific characteristics, which require strict handling and limitations, as mentioned later below.

Here’s why lithium batteries pose risks to aircraft:

• High Energy Density: These batteries store significant energy in compact units, boosting efficiency but also increasing the risk of overheating and combustion if mishandled.
• Flammable Electrolytes: The liquid or gel inside these batteries is highly flammable, meaning any breach can lead to ignition.
• Thermal Runaway: If one cell overheats due to a fault, short circuit, or external damage, it can trigger a self-sustaining cycle where nearby cells overheat. This chain reaction can quickly lead to a fire or even an explosion, making it extremely dangerous in confined spaces like an aircraft.

Lithium batteries are composed of multiple smaller units called cells, each capable of storing and releasing energy. These cells are interconnected to form the battery, and a malfunction in one cell can affect the others, amplifying risks like thermal runaway.

Flying with Batteries: What Are the Limitations?

PLEASE NOTE: THIS BLOG POST IS FOR INFORMATIONAL PURPOSES ONLY. ALWAYS CONSULT YOUR AIRLINE OR AVIATION AUTHORITIES IF IN DOUBT.

Whenever you think about packing batteries, there is one question: are they spares or installed in equipment? Generally speaking, batteries installed in equipment are allowed, whereas spare batteries are usually restricted.

In most cases, you can bring batteries in your carry-on luggage, but you cannot pack them in checked luggage.

Here’s a quick overview of the general limitations for batteries:

• You can bring personal electronic devices with lithium batteries in your carry-on luggage. You may also pack these devices in checked baggage if you securely pack them to prevent accidental activation.
• Spare Batteries and Power Banks: You must never place spare batteries and power banks in checked luggage. They are only allowed in carry-on luggage.
  • Spare batteries must be individually protected to prevent short circuits, such as by taping the terminals or placing them in plastic bags.
  • I know this will come as a surprise, but EASA (the authority responsible for ensuring civil aviation safety across Europe) requires that spare batteries and power banks must not be used to charge devices or recharge while onboard.
• Size Limits:
  • Batteries up to 100 Wh (lithium-ion) or 2g lithium content (lithium-metal) are allowed without airline approval.
  • Batteries between 100–160 Wh require prior airline approval.
    • No more than two individually protected spare batteries in the range of (100 Wh – 160 Wh) per person may be carried. (FAA, UK, EASA, CATSA)
  • Batteries exceeding 160 Wh are prohibited.

“Spare batteries, including power banks, should not be recharged while on board the aircraft. Additionally, power banks should not be connected or providing power to a device while on board the aircraft.” (EASA / More practical information – Lithium batteries document)

Common items and their restrictions:

Let’s take a look at a few common items and their restrictions:

• E-cigarettes and vapes: 
  • Restriction: max. 100 Wh or 2 g lithium content.
  • NOT Allowed in checked baggage.
  • Allowed in carry-on baggage.
    • Lithium-metal batteries must not exceed 2g.
    • Lithium-ion batteries must not exceed a watt-hour rating of 100 Wh.
    • Recharging of the devices and/or batteries onboard is prohibited.
  • Airline approval is not required and the pilot-in-command doesn’t have to be informed about the item’s location.
  • Devices must be protected to prevent accidental activation.

• Baggage with installed NON-REMOVABLE lithium batteries (Smart baggage):
  • Restriction: max. 2.7 Wh or 0.3 g lithium content.
  • If the smart baggage has non-removable batteries NOT exceeding–0.3 g lithium metal or 2.7 Wh, it is allowed as checked or carry-on baggage.
  • If the batteries exceed these limits, the baggage is strictly prohibited as either checked or carry-on luggage.

• Baggage with installed REMOVABLE lithium batteries (Smart baggage):
  • Restriction: max. 100 Wh or 2 g lithium content.
  • If the smart baggage has removable batteries that do not exceed 2g lithium metal or 100 Wh, it is allowed as checked or carry-on luggage. However, you must remove the batteries and carry them in the cabin.
  • If the batteries exceed 100 Wh but are under 160 Wh, the baggage is allowed as checked or carry-on luggage. However:
    • You must remove the batteries and carry them in the cabin.
    • Airline approval is required.
    • Passengers are limited to two batteries per person.

• Earbuds (wireless) / AirPods:
  • NOT Allowed in checked-in baggage.
  • Allowed in carry-on baggage.
  • The chargers for earbuds and AirPods are considered a type of power bank, which is why they are restricted from checked luggage.

• Small Cigarette Lighters (Soft flame lighters):
  • Must not contain unabsorbed liquid fuel, except liquefied gas.
  • Allowed on your person only. Keep the lighter with you at all times when onboard the plane.
  • DO NOT PACK it in checked or carry-on luggage.

• Large Lighters (eg. BBQ Lighters), Blue flame lighters (Cigar lighters/Torch lighters):
  • FORBIDDEN, keep them at home.

How to calculate the watt-hour (Wh) rating of your item?

You can calculate the watt-hour (Wh) rating of a lithium-ion battery using the following formula:

Wh = Ah x V

Where:

Ah is the battery’s capacity in ampere-hours.

V is the battery’s nominal voltage.

If the battery only lists the capacity in milliampere-hours (mAh), divide that number by 1000 to convert it to ampere-hours (Ah).

For example: 4400 mAh ÷ 1000 = 4.4 Ah.

If you’re unsure of your battery’s watt-hour rating, refer to the device’s user manual or contact the manufacturer.

Note that:

The above restrictions are based on various authorities: EASA, TSA, UK CAA, CATSA (Canada), NZ CAA, and IATA documents. However, airports and airlines may sometimes impose additional restrictions, although this is uncommon, as they typically follow the guidelines set by the relevant aviation authorities, which usually align with IATA recommendations.

Before travelling, always review your airline’s dangerous goods policies. If in doubt, contact them directly or ask at the check-in desk.

Here is a quick summary of battery regulations:

How do you request airline approval to carry an item considered dangerous goods?

It depends on your airline, but it’s usually one of the following options:

• Via their website when you check-in: An online authorisation.
• At the check-in desk:
  • Here, they may provide you with a form to fill out, or they may give verbal permission.

Consult with your airline’s help centre on what’s their best method earlier on, you never know if an airline requires a 48-hour notice period for certain items.

Incidents That Shaped Aviation Regulations on Lithium Batteries

Three high-profile incidents have shaped the regulations on lithium batteries nowadays:

• UPS Flight 1307 (2006): A Douglas DC-8 cargo plane caught fire in-flight, prompting an emergency landing at Philadelphia International Airport. The crew suffered smoke inhalation but no serious injuries. Most of the cargo survived, but the aircraft burned on the ground for several hours, leaving multiple holes in its roof. The investigating authority suspected lithium-ion batteries caused the fire.
• UPS Flight 6 (2010): Lithium batteries in the cargo hold sparked a fire, leading to the crash of a Boeing 747 near Dubai. Both pilots died.
• Asiana Airlines Flight HL7604 (2011): A fire caused by lithium batteries led to the crash of a 747 cargo plane into the sea, resulting in the deaths of both pilots.

Between March 2006 and October 2024, the FAA recorded 504 verified lithium battery-related incidents (involving smoke, fire, or extreme heat). Of these, 364 occurred on passenger aircraft.

In 2024 alone, the FAA confirmed 32 incidents involving lithium batteries.

Flying with lithium batteries is a serious concern. However, due to their widespread use in everyday items, the aviation industry cannot simply ban them. Instead, it must establish rules and regulations to mitigate the associated risks. Even with these precautions, when passengers comply with regulations, faulty products from manufacturers can still cause issues. This brings us to one strictly prohibited item: any device with a recalled battery.

Recalled Batteries – Samsung Galaxy Note 7s

Defective or recalled batteries continue to pose significant aviation safety concerns.

What is a recalled battery?
Manufacturers recall batteries that do not perform as expected and may present a safety hazard. Recalled batteries may not display any visible damage. (call2recycle)

One of the most infamous devices banned by the FAA and several airlines is the Samsung Galaxy Note 7, which had a battery defect that caused many units to overheat or explode. This led to widespread chaos within the industry following hundreds of reported incidents.

The FAA banned the Samsung Galaxy Note 7 from being carried aboard any flight, even if powered off. Other airlines imposed the same restriction.

If passengers attempt to travel by air with their Samsung Galaxy Note7 devices, they will be denied boarding. (US Department of Transportation)

EASA followed a more light approach, allowing passengers to bring their phones aboard, but they must be turned off and must not be charged while on board.

How to Check if Your Battery Is Recalled:

• Visit the manufacturer’s website for recall notices.
• If in doubt, contact the manufacturer’s customer support.

Carrying recalled batteries in checked or cabin luggage can result in fines or denied boarding, so it’s crucial to verify beforehand.

Why Are Batteries Allowed in Hand Luggage But Not in Checked Luggage?

This common question boils down to two things: accessibility and safety.

Accessibility:

Batteries in the cabin can be quickly monitored, and any overheating can be addressed by the crew.

Fun Fact: When you pull the trigger to extinguish a bottle on the 737, you can’t stop-it midway, the whole bottle will extinguish regardless!

Fire Suppression:

Aircraft cargo holds are equipped with fire suppression systems, but these systems are designed to handle general fires, not specific, ongoing battery fires.

For example, on a 737, there are two fire extinguishing bottles for the cargo hold. If a fire starts due to a lithium battery (like one from a phone), and both bottles are used to put it out, there may be no remaining suppressant to handle a second fire that occurs later. This is problematic because, without enough extinguishing capability, another fire could start from a different source, and the crew would have no way to suppress it.

Imagine if you’re on a flight and a fire starts from a phone in the cargo hold. The crew uses both fire extinguishers to control that fire, but then, later in the flight, another item—let’s say a power bank or laptop—begins to overheat and catch fire. With no remaining fire suppression, that second fire could spread, potentially making its way into the cabin, where the crew and passengers are at risk.

Even if the fire was under control, you now have to divert causing delays and more problems to everyone aboard.

Therefore, it’s safer to keep batteries “in sight.” If your lithium battery starts overheating, it can be dealt with immediately. This way, you can be confident that the fire is under control, allowing your flight to continue safely to its destination.

In summary, lithium battery fires in the cabin can be addressed immediately using extinguishers or fire containment techniques by the crew. This ensures the fire doesn’t spread to other areas of the plane, maintaining a safer environment. Prompt action also enables the crew to make better, more effective decisions, ultimately keeping everyone onboard safer.

Power bank fire on board China Southern CZ3539, Feb 25 2018.😱😱 pic.twitter.com/cby6E62qRv

— ChinaAviationReview (@ChinaAvReview) February 25, 2018

What Happens If You Leave a Lithium Battery in Checked Luggage?

If you accidentally leave a battery in your checked luggage, inform the airline immediately. This may cause delays, as ground staff might need to retrieve your luggage for inspection or to remove the battery. Double-check your bags before check-in to avoid this situation.

Fun Fact: Pre-2010 Restrictions on batteries

For primary lithium batteries, the maximum lithium content allowed for passenger aircraft is 25 grams, and they are prohibited on passenger aircraft if they exceed that.

For secondary lithium batteries carried by passengers, the lithium content is limited to 8 grams of ELC per battery, with some allowances for batteries containing up to 25 grams of ELC.

What to Do If a Battery Fire Occurs Mid-Flight

In the rare event of a battery fire or overheating during a flight, cabin crew are trained to handle such situations swiftly and efficiently:

If you notice that your battery is hotter than usual or suspect it’s overheating, inform the cabin crew immediately.

1. Detection: The crew will quickly identify the source of smoke or fire, usually caused by overheating devices.
2. Isolation: The device will be placed in a fire containment bag, if available, or submerged in water or a non-flammable liquid to cool it down.
3. Fire Suppression: If the device catches fire, the crew will use onboard fire extinguishers to combat the flames.
4. Communication: Passengers will be instructed to remain calm and seated while the crew manages the situation.

Advice for Passengers:

• Inform the crew immediately if you notice a device overheating or emitting smoke even if it’s not yours.
• Avoid attempting to move or extinguish the device yourself.
  • If you see smoke coming from an overhead storage compartment, do not attempt to open it. Instead, inform the cabin crew immediately.

Latest video footage shows the tensed moments after a laptop battery caught fire inside the American Airlines flight at SFO.

Flight attendants and the pilot can be heard asking passengers to leave their bags and get off the plane.

At least three people were injured during the… https://t.co/KHXT3dxqFm pic.twitter.com/QW5eeY9tKs

— FL360aero (@fl360aero) July 13, 2024

Practical Tips for Travellers

I understand that this article might seem overwhelming with all the regulations and restrictions to follow. However, most of the time, you’ll be fine with the devices you’re packing and carrying.

Here are a few tips to help when packing batteries:

1. Spare Lithium Battries:
   • When packing spare lithium batteries, make sure to keep them in their original packaging or a protective case to prevent short circuits.
2. Charge Devices Wisely:
   • Avoid overcharging devices, as it increases the risks during travel.
   • Charge your devices at home or at the airport terminal so you don’t have to recharge them during the flight.
   • On long flights, many airlines equip seats with charging ports, so use those instead of your power bank, even if they are “slow-charging” ports.
3. Review Rules for Specific Items:
   • If you’re travelling with items like drones, smart luggage, or power tools, make sure to review the airline’s regulations.
   • Visit the airline’s dangerous goods page, as every airline publishes this information online. When checking in online, you’ll also be shown a list of prohibited dangerous goods items and asked to confirm that you’re not carrying any of them. Don’t skip through the list—take a moment to review it before confirming.
4. For High-Capacity Batteries:
   • Always keep the original packaging with you. If you plan to discard it, at least take a photo of the packaging and keep it on your phone. Alternatively, make a note of the lithium content or watt-hour (Wh) rating to avoid lengthy questioning during security screening.

Future of Lithium Batteries in Aviation

Aviation works at balancing the safety of lithium batteries with innovation. Beginning in 2026, the 30% State of Charge Rule will require lithium-ion batteries shipped in cargo to be partially discharged to reduce fire risks. This regulation will not apply to personal electronic devices carried by passengers.

Looking ahead, emerging technologies such as solid-state and lithium-sulfur batteries hold promise to provide safer, efficient alternatives. These might limit the possibility of thermal runaway while still providing high energy density.

Key Takeaways – Why Are Batteries Dangerous Goods?

Batteries, especially lithium-based ones, are essential to modern life but pose risks that make them a focus for aviation safety. Aviation authorities classify them as dangerous goods because they can:

• Overheat and catch fire.
• Cause chain reactions (thermal runaway).
• Give rise to hardly controllable fires, especially in confined spaces.

Strict regulations ensure safety without compromising the convenience of travelling with essential devices.

Strict regulations are in place to ensure safe travel with these essential devices. As technology advances, ongoing improvements in both battery design and regulations will help maintain safety while allowing us to keep enjoying the benefits of these devices.

Useful resources to check if your item is not a Dangerous goods

There’s a hefty IATA Dangerous Goods Regulations (DGR) document—about 1,200 pages long—but I’m fairly certain it’s not something most passengers will want to dive into. Still, if you’re feeling brave, you can order it from here.

For more practical resources, I recommend the following:

• Your airline’s DGR page: Simply search “Your airline name + Dangerous Goods” on Google, and you’ll find a list of restricted items for your airline. Some useful links include:
  • Qatar Airways Restricted baggage items
  • United Dangerous items
  • Ryanair Prohibited Items
  • Air New Zealand prohibited & restricted items
• Recalled items: The New Zealand government provides a reliable resource for recalled items here.
• TSA Can I bring It?: This excellent tool helps you check if an item is considered dangerous for air travel. Although it’s American, it’s widely used and works for most countries
• “UK CAA What items can I travel with“: This is a comprehensive list to check for prohibited items when packing.

These resources should give you the information you need and are easy to use for passengers. If in doubt, always ask your airline, airport security, or cabin crew.

I hope this article has given you valuable insight into lithium batteries in aviation and the broader world of dangerous goods.