Key Facts
- ✓ Laptop power banks typically have capacities between 20,000mAh and 27,000mAh.
- ✓ The TSA limits carry-on batteries to 100 watt-hours (approx. 27,500mAh).
- ✓ Voltage conversion results in an average efficiency of 60 percent, delivering about a 75 percent charge to a laptop.
- ✓ Recent onboard fire incidents involving battery packs occurred on flights by Delta, KLM, and Hong Kong airlines in 2025.
- ✓ Wireless charging on power banks has improved but remains less efficient than wired connections.
Quick Summary
Laptop power banks provide essential backup power for travelers and remote workers. These devices typically hold between 20,000mAh and 27,000mAh, allowing them to refill a laptop battery to approximately 75 percent. Because they fall below the 100-watt-hour limit, they are generally permitted in carry-on luggage.
Recent safety concerns have led to stricter airline policies. Following onboard fire incidents, carriers like Delta, KLM, and Hong Kong-based airlines have implemented rules requiring power banks to remain visible during use. When choosing a device, users should look for multiple USB ports with varying wattages to ensure fast charging. It is also important to understand that listed capacity does not equal delivered power due to voltage conversion inefficiencies. Wireless charging is available but less efficient than wired connections.
Air Travel Regulations and Safety 🛫
Most portable laptop chargers are designed to comply with airline regulations. The TSA currently limits carry-on battery capacity to 100 watt-hours (Wh), which corresponds to approximately 27,500mAh for standard lithium-ion batteries. Passengers are strictly prohibited from packing batteries in checked luggage, regardless of capacity.
These rules are intended to mitigate fire risks. Recent onboard incidents have prompted several airlines to introduce additional restrictions. In March 2025, a battery pack caused a fire on a Hong Kong flight, grounding the plane. Similar events occurred on Delta and KLM flights later that year. Consequently, airlines such as Emirates and Southwest now require:
- Limitations on the number of portable chargers allowed per passenger
- Power banks to remain in clear view when actively charging devices
- Devices to be stowed in carry-on bags if not in use
Travelers are advised to verify specific airline policies before flying.
Capacity and Efficiency ⚡
For users needing to revive multiple devices or a laptop, a high milliamp-hour (mAh) capacity is necessary. Power banks capable of charging laptops generally range from 20,000mAh to 27,000mAh. For those who do not need to fly, portable power stations offer larger capacities, sometimes the size of a car battery, capable of powering devices for an entire weekend.
However, the listed capacity on a power bank does not reflect the actual charge delivered to a device. Due to differences in voltage—typically 3.7V for power banks versus 11.4V for laptops—and energy loss during voltage conversion, efficiency rates average around 60 percent. Consequently, a 25,000mAh (92Wh) power bank will typically charge a 5,000mAh (72Wh) laptop battery to about 75 percent.
Ports and Connectivity 🔌
Large power banks typically feature at least three USB ports, including a mix of USB-C and USB-A. These ports often supply power at different wattages; for example, a device capable of 70W fast charging should be connected to a 100W port to maximize speed. Devices will only draw the power they can handle, so connecting a low-wattage device to a high-wattage port is safe.
Some units include AC ports, but these are intended for devices that cannot use USB, such as lamps or printers. Using an AC port for a laptop requires converting DC to AC and back to DC, which wastes energy. For maximum efficiency, DC power should be sent directly to the device. Additionally, while wireless charging has improved and is now impressively fast—particularly for Samsung Galaxy phones—it remains less efficient than wired connections.
Design and Testing 🧪
Laptop power banks are significantly larger than phone chargers, weighing between 1.5 and 2 pounds. Many models include a digital display showing remaining charge, which helps users manage power distribution. Users should be aware that wireless pads often require a button press to activate.
Testing involves draining devices to low battery levels and measuring refill times and capacity usage. Devices tested include the Zendure Supertank Pro, Mophie Powerstation Pro XL, Lion Energy Eclipse Mag, Anker Prime, and UGreen Power Bank. The HyperJuice 245W, noted for its 27,000mAh capacity and four USB-C ports, successfully charged a MacBook Pro to 75 percent but lacks port variety and is priced higher than competitors.
