A milliamp-hour figure does not translate directly into a number of full phone charges. Some energy is lost during conversion and results vary with voltage, cable and operating mode. Choose for the task, weight and compatible outputs rather than the largest headline number.
01A practical selection process
- For daily backup, estimate how many phone top-ups you need rather than relying only on rated capacity.
- Match output power and protocol to the phone, tablet or laptop.
- Check which port recharges the power bank itself and whether a suitable cable is included.
- Allow for size and weight; a very large unit may be inconvenient to carry every day.
- Before flying, check the current battery rules of the specific airline you will use.
Unsafe battery warning signs
Do not use a power bank that is swollen, cracked, leaking, smells unusual or heats sharply. Keep it out of direct sun and do not charge it on a soft, unventilated surface. Retain the label: the watt-hour value is often useful for travel and specification checks.