This compact $89 USD power bank can hold a respectable 63 Wh charge to be perfect for hikes or camping trips with multiple people. Recharging the bank itself, however, is almost three times slower than on most laptops.
https://www.notebookcheck.net/Portable-Eggtronic-battery-bank-holds-a-larger-charge-than-most-laptops.494765.0.html