Yes, but the rules in 2026 are stricter than ever due to fire safety concerns. Lithium-ion batteries and power banks must always be in carry-on luggage; they are strictly prohibited in checked bags because a fire in the cargo hold is much harder to extinguish. Most airlines allow batteries up to 100 Watt-hours (Wh) without prior approval. For larger batteries between 100Wh and 160Wh (common in high-end camera gear or professional laptops), you generally need advance airline permission, and there is a limit of two per person. A new regulation for 2026 from many carriers, including the Lufthansa Group, now prohibits the use or charging of power banks during the flight; they must remain stored under your seat or in your pocket to prevent overheating. Always ensure the "Wh" rating is clearly printed on the device; if security cannot verify the capacity, they may confiscate it. For reference, a standard 20,000mAh power bank is typically around 74Wh, making it perfectly legal for carry-on travel.