For flights to the USA, the key limit is 100 watt-hours (Wh) per power bank without needing airline approval. Power banks between 101 Wh and 160 Wh usually require airline approval and are typically limited to two per passenger. Above 160 Wh is generally prohibited on passenger aircraft. Power banks must be carried in your hand luggage, not checked baggage.
To convert capacity to Wh:
Wh = (mAh × battery voltage) / 1000
For a typical lithium-ion power bank (3.7 V cells):
- 20,000 mAh ≈ 74 Wh
- 26,800 mAh ≈ 99 Wh
- 27,000 mAh ≈ 100 Wh
So 26,800 mAh is about the largest commonly available power bank that stays under the 100 Wh limit.
For your PicoMuon flight experiment, I would look for:
- Around 26,800 mAh (99 Wh) capacity.
- An “always-on” or “low-current mode” specification.
- USB output that remains active below 100 mA load.
A 99 Wh power bank should run a PicoMuon for several days continuously, assuming the power bank does not auto-shut off.
Yes. On flights to the USA, you can normally carry more than one power bank, provided:
- They are in your carry-on baggage (not checked luggage).
- Each power bank is 100 Wh or less.
- The terminals are protected against short circuits (usually by keeping them in their cases or separate pockets).
Most airlines allow at least two power banks under 100 Wh, and many allow several. The exact number can vary by airline, but carrying two standard power banks (e.g. two 20,000–26,800 mAh units) is normally unproblematic.
For your PicoMuon experiment, two 26,800 mAh (99 Wh) power banks would give you nearly 200 Wh total, while still complying with the usual per-battery limit.
For Air France, you can carry up to 2 power banks per person in your cabin baggage. They must:
- Be carried in hand luggage, never checked baggage.
- Be kept with you and not stored in the overhead locker.
- Not be used or recharged during the flight.
- Be no more than 160 Wh each. If a power bank is between 100 Wh and 160 Wh, Air France requires prior approval.
For your PicoMuon trip, the simplest option is:
- 2 × 99 Wh power banks (about 26,800 mAh each)
These are below the 100 Wh approval threshold, so no special permission is normally required, and together provide nearly 200 Wh of energy.
One thing to note: Air France specifically says power banks must not be used on board. If your intention is to power the PicoMuon continuously during the flight, that technically conflicts with their current policy on using power banks in flight.
For a muon-counting experiment during the flight, you may be better off running the PicoMuon from its own internal battery (if fitted) and logging locally, or checking with Air France beforehand regarding powering scientific equipment during the flight.