Being somewhere unfamiliar with 3% battery is a special kind of stress

A phone can be the map, ticket, payment card, hotel address, and way to contact someone, all at once. That is convenient right up until the battery runs low in an unfamiliar place. Carrying a charger helps, but it still depends on finding somewhere to plug it in. What information is worth keeping outside the phone? A written address and an agreed meeting point sound old fashioned until they are useful. Share small preparations that make travel or a long day out less dependent on one working device.