Lithium batteries must be in hand luggage, not checked
The main difference between carry‑on and checked baggage is where lithium batteries are placed. All spare lithium batteries and external chargers (power banks) must not go in checked luggage; they must be in carry‑on baggage and taken into the cabin.
The reason is simple: if a lithium battery short‑circuits, is crushed or overheats and catches fire, there is no one in the cargo hold to deal with it immediately, and the fire spreads quickly; in the cabin, the crew have firefighting equipment and can react instantly. Therefore, whether it is a spare cell or a power bank attached to a phone, it must be carried in hand luggage.
Airlines may have different limits on the capacity (in watt‑hours) of lithium batteries carried in hand luggage; exceeding a specific capacity or type may require prior declaration. Check the exact figures with your airline before departure.
Power bank must be kept with you: place in carry‑on luggage, not in checked baggage.
A power bank is a portable charger; its lithium battery is the same type as above, so the same rules apply: carry it in hand luggage, not in checked baggage.
Another benefit of carrying it with you is practicality: on long flights, after landing you may need to go to a hotel, find transport or use navigation, which drains your phone battery. Having a power bank in your carry‑on lets you recharge immediately after disembarking, without having to look for a charging point on the street.
When packing, be especially careful: do not hide a power bank at the bottom of your checked bag — it is not only against the rules, but if something goes wrong there is no one to handle it in the cargo hold. Keep it with you, in your own carry‑on bag.
100ml liquid rule: why some cosmetics can't be taken in hand luggage
Liquids, gels and aerosols in hand luggage generally follow this rule: each container must not exceed 100ml; all containers must be placed inside a clear, resealable plastic bag (commonly marked 1 litre capacity); each passenger is allowed one bag.
The key point is that each container must not exceed 100ml, not that the total is 100ml. You can bring three 50ml liquids, but a 150ml bottle of facial cleanser, even if partly used, cannot be taken in hand luggage and must be moved to checked baggage.
Common travel liquids include: sunscreen, toner, eye drops, liquid lipstick, spray bottles (after checking, empty them, or switch to a collapsible bottle). Liquids that cannot pass hand‑luggage screening should be moved to checked baggage. Airlines may differ slightly in their details, so check with your airline before departure.
Sharp objects and aerosols: which go in checked baggage, which need to be checked with the airline
Sharp objects generally must be placed in checked baggage, not in hand luggage. Common items to check in: eyebrow scissors, nail clippers, razors (shaving razors), small knives, scissors; similar sharp objects also go in checked baggage.
Aerosols fall into two categories: ordinary non‑pressure aerosols can usually be taken in hand luggage, but are subject to the 100ml liquid rule above; pressure aerosols (such as aerosol hair sprays, some sunscreen sprays, makeup removal sprays) are subject to separate capacity and total limits set by each airline, which vary.
It’s unclear whether an item counts as carry‑on or checked baggage; the safest approach is to check it in, and confirm with the airline before departure for the most accurate information.
eSIM: No need to worry about your phone running out of power during your trip.
Having covered baggage, now back to the internet. For those who install eSIM before travel, the biggest worry during the trip is 'what if my phone runs out of power?' Actually, there’s no need to worry too much: the eSIM is stored on the device, the plan follows the phone; if the phone is out of power, it’s just temporarily off, not that the plan disappears, and it works again once charged.
So the correct pre‑trip preparation is two things: fully charge your phone before departure, and keep a power bank in your carry‑on. Whether mid‑flight, after landing, or on the way to the hotel, whenever the phone's battery is low, charge it immediately. As long as you have 'phone + power bank', the eSIM plan will not be suspended or invalidated due to low power.
When to install the eSIM before travel, how the days are counted, and whether to enable data roaming at the destination — these are covered in a separate checklist, see Pre‑trip SIM checklist. For example, when going to Japan, you'll need data immediately for navigation and contacts, so managing your phone's battery becomes even more important.
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