Power Up Your Phone by Hand or by Sun

Q. As recent storms and power outages have shown, we are now deeply reliant on cellphones for communication, especially since many people have gotten rid of their landlines. If there’s no electricity, what options do you have for charging a phone battery?

A. Backup batteries only last for so long, but hand-cranked chargers and miniature solar panels are two options for restoring a little power to your mobile phone. Adding an alternative charging device to your household emergency kit (along with the flashlights and candles) is one way to stay in contact with others, but keep in mind that for large-scale outages, network cellular service and Wi-Fi routers will most likely be down as well.

Several companies make hand-cranked chargers, including Etón and K-TOR. Prices start at about $17 for a simple crank and go up from there.

To use one, connect the phone to the device with its USB charging cable and then turn the crank continuously until you see the phone’s battery level move up a notch or two. Depending on the devices involved, this can take several minutes of cranking, but you should be able to get enough power to make an emergency call — which can be helpful if, say, your house is having power problems of its own and you need to call an electrician.

If hand-cranking does not appeal to you, Etón also offers solar-powered solutions and K-TOR has a pedal-powered charger for about $200.

Portable solar-powered chargers can supply energy to devices in emergency and nonemergency situations (like camping) without physical effort. Wirecutter, a New York Times company that reviews products, tested 70 solar battery chargers and found the $51 Anker PowerPort Solar Lite to be the best model for juicing up mobile devices.

Smartphone cases with built-in solar chargers are another option, even for everyday use. SnowLizard makes cases for current iPhone models and the Portable Solar Shop site sells cases for several Android phones.