Power Banks for Mobile Phones

How to choose a power bank

• Capacity - decide how many times you want to charge your phone or tablet. For example: The power bank has a capacity of 10,000 mAh and the tablet has a battery of 3,000 mAh. The factor 0.85 (85%) indicates efficiency – we lose some energy due to voltage conversion, heating, and internal losses. 
  This means that the power bank can charge the tablet approximately 2.8 times, i.e., twice fully and one additional partial charge. Number of charges = (10,000 × 0.85) ÷ 3,000 ≈ 8,500 ÷ 3,000 ≈ 2.83
  It is also important to remember that as the capacity increases, so does the weight of the power bank.

• Output power - phones usually 20-30 W, tablets more, laptops need higher power. USB-C Power Delivery can handle up to 240 W, which is useful for more demanding devices.

• Charging protocols - look for USB-C PD (or PPS) for universal fast charging. Quick Charge is common on some phones.

• Ports- a combination of USB-C and USB-A allows you to charge multiple devices at the same time, even with older cables.

• Power bank charging speed - prefer fast input via USB-C so that it charges itself in a matter of hours, not overnight.

• Safety and certification - check for UL 2056 testing and compliance with European CE/EN 62368-1 requirements. This reduces the risk of overcharging, short-circuiting, and overheating.

• Durability and portability - choose the capacity, weight, and size ratio depending on whether you carry the power bank with you every day or use it more on weekends. Aluminum covers can withstand slightly bigger drops and cool better than plastic ones.

Flying with a power bank

• Yes in the cabin, no in checked baggage. 

• Up to 100 Wh without special approval. 101-160 Wh usually only 2 pieces and with airline permission. Above 160 Wh is generally prohibited.

• Don't have the Wh listed? Convert from mAh: mAh ÷ 1000 × V. 

Quick guide by use

• Phone for the whole day - 10,000-12,000 mAh with USB-C PD.

• Multiple devices for the weekend - 20,000 mAh and above, multiple ports.

• Laptop via USB-C - look for PD power of 60-100 W and above, depending on the device's requirements.