Hanover The Federal Office for Civil Protection and Disaster Relief advises citizens to keep crank radios available for emergencies. This does not have to be expensive: the devices are already available in mail order for 20 to 50 euros, as the experts from “c’t” report. With a charged battery, the six tested radios all run for several days. If it is empty, you have to crank it for about a minute to be able to listen to the radio for five to ten minutes. Solar cells for an emergency It is more convenient to charge with the help of built-in solar cells. All tested devices have these. According to the testers, the few square centimeters were only enough to listen to the radio even in full sun – and not to fully charge the battery. Her tip: do not put the emergency radio in the dark drawer, but put it on a window sill. Thus, the modest charging effect can also be used to compensate for the usual, creeping discharge – and to keep the emergency radio operational for years. According to the testers, a good emergency radio also has functions such as an emergency siren, an emergency light or an emergency reading light. These are available on all tested crank radios. Less convincing: the setting options of the transmitter. Sometimes it takes surgical precision to adjust the frequency of a particular transmitter, the testers judge. Only the “Renkforce RF-CR-200” model has a digital display with which you can control transmitters in a targeted manner. The testers attest the best sound quality to the model “Degen DE13”.