If you are in an emergency situation far from an outlet to charge your smartphone or tablet, hand-crank charger could be a true life saver. All you need is to plug it in using a USB cable and to give several hundred cranks. Unlike solar smartphone and table chargers, hand-powered chargers demand some physical effort and cannot provide long-lasting results, but it is true that advanced models can charge your portable device at the same rate it would charge in a standard household electric outlet. Another positive feature of dynamo hand-crank charger is that it is operating equally 24 hours a day, while solar chargers rely on the sun to generate electricity. These self-powered chargers are indispensable for camping and hiking, as well as for emergency situations and natural disasters. No doubt, it should be included into any standard survival kit. Another reason for having a hand-crank charger at hand is short battery life of portable devices. Smartphones and tablets help us find information quickly and stay connected non-stop, but all modern applications suck the life out of them very quickly. It is difficult to last 12 hours on one charge and you never know when your battery is going to unexpectedly die. So, having a dynamo charger at hand is a good solution even for city life.