Phones, laptops, cameras and power banks all use lithium batteries. When flying, many passengers wonder where to put them and how many they can bring. The basic principle is not complicated: spare lithium batteries and power banks must be in carry-on baggage, and the battery capacity determines whether you need the airline's permission.
Why are lithium batteries so tightly regulated?
A lithium battery that is damaged, short-circuited or knocked can overheat and catch fire. In the passenger cabin the crew can respond early; in the cargo hold the risk is harder to control. That is why aviation rules restrict lithium batteries, especially loose ones.
Basic rules (general industry knowledge)
IATA's lithium battery guidance page states clearly that spare batteries must not be placed in checked baggage. The rules airlines commonly apply include:
| Battery capacity | Common rule |
|---|---|
| Under 100 Wh | Carry-on baggage, usually no permission needed |
| 100 to 160 Wh | Carry-on only, airline approval required, limited quantity (usually up to two) |
| Over 160 Wh | Not allowed on passenger aircraft |
In addition:
- Power banks and loose batteries: carry-on baggage only.
- Batteries installed in devices: devices (phones, laptops) can usually go in both carry-on and checked baggage if fully switched off, but many airlines recommend keeping them with you; check the airline's rules.
- Damaged, swollen or leaking batteries: not allowed on the aircraft.
- Protect battery terminals: cover the terminals or keep each battery in its own packaging or pouch to prevent short circuits.
- Each airline and country may apply stricter rules, so check before your flight.
How to calculate Wh from mAh
Power banks usually show mAh on the casing. An approximate conversion: Wh = (mAh ÷ 1000) × voltage (V). For lithium batteries the nominal voltage is usually 3.6–3.7 V. For example, a 10,000 mAh power bank at 3.7 V gives about 37 Wh; a 20,000 mAh one is about 74 Wh. If Wh is already printed on the casing, use that number. If the capacity is unclear, check the label or ask the manufacturer.
Tips for preparing before your flight
- Put power banks and loose batteries in a carry-on bag or backpack, not in checked luggage.
- Bring labels with legible specifications so security staff can check them if needed.
- Fully charge your phone and devices before heading to the airport.
- Check the rules again with your airline before the flight date, especially if you are bringing many batteries or high-capacity ones.
2026 update: The rules have been tightened. According to the UK Civil Aviation Authority (UK CAA), from 27/3/2026 passengers may carry at most two power banks each, kept in carry-on baggage; the power bank itself must not be recharged on board and must not be used to charge other devices during the flight. Lithium-ion power banks up to 100 Wh need no airline permission, while those above 100 up to 160 Wh need airline approval. In Vietnam, according to the press, Vietjet said it follows Directive 1027/CT-CHK of 26/2/2025 of the Civil Aviation Authority of Vietnam; Vietnam Airlines said power banks must not be plugged into the USB port on board and must not be used to charge devices during the flight. Check the latest notice from the airline you fly with.
If you need help with baggage or your itinerary, you can contact the HVSC flight ticket team.
FAQ
Can I put a power bank in checked luggage?
No. According to IATA's lithium battery guidance page, spare batteries must not be placed in checked baggage; power banks must be carried in carry-on baggage.
Can I take a 20,000 mAh power bank on a plane?
This battery usually converts to about 74 Wh, so it is under 100 Wh and allowed in carry-on, but check the specifications on the label, the airline's current rules and the permitted quantity.
What about batteries built into laptops and phones?
Devices with built-in batteries usually have their own rules, which can differ between airlines. The safety recommendation is to keep them with you in carry-on baggage and switch the device off completely.
Reference sources
- IATA — Lithium batteries (Dangerous Goods): https://www.iata.org/en/programs/cargo/dgr/lithium-batteries/
- UK CAA — Changes to rules on the carriage of lithium cells/batteries and power banks: https://www.caa.co.uk/commercial-industry/airlines/dangerous-goods/changes-to-rules-on-the-carriage-of-lithium-cellsbatteries-and-power-banks/
- Saigon Economic Times/Tuoi Tre — Vietnam Airlines and Vietjet ask passengers not to use power banks on board: https://tuoitre.vn/saigontimes/vietnam-airlines-va-vietjet-de-nghi-khach-khong-dung-sac-du-phong-tren-may-bay/
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FAQ
Can I put a power bank in checked luggage?
No. According to IATA's lithium battery guidance page, spare batteries must not be placed in checked baggage; power banks must be carried in carry-on baggage.
Can I take a 20,000 mAh power bank on a plane?
This battery usually converts to about 74 Wh, so it is under 100 Wh and allowed in carry-on, but check the specifications on the label, the airline's current rules and the permitted quantity.
What about batteries built into laptops and phones?
Devices with built-in batteries usually have their own rules, which can differ between airlines. The safety recommendation is to keep them with you in carry-on baggage and switch the device off completely.
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