There are different kinds of portable chargers, and some hold a more substantial charge than others which means you'll have more accessible power for your phone. Buying one that can save a lot of energy will ensure you won't struggle to find a charging station on your trip. Although this might be another thing to carry, they aren't very heavy, and you'll find yourself thankful for choosing to bring it.
The very last thing anyone wants to worry about on vacation is finding a place to charge your cell phone or any other devices you might carry on your journey.