The test winners Aukey PB-Y17 (5000 mAh, 20 euros), GP International MP10MA (10000 mAh, 40 euros) and Ansmann Powerbank 20.8 Type C (20000 mAh, 38 euros) are also reliable power providers.) Those who make slight concessions in terms of endurance and functions can get even better value for money with the price-performance winners: the Ansmann Powerbank 5.4 is already available for 15 euros, the larger...