Shopping for hardware to tide you through the next hurricane? The Electric Power Research Institute has some advice, none of it encouraging.
The institute, a nonprofit research consortium of the utility companies, examined ways of charging a smartphone or an iPad without house current. A profusion of gadgets now have hand-crank generators, often incorporating a flashlight or a radio, with a USB receptacle or even an AC outlet for recharging a small hand-held device. There are also solar-powered rechargers that may have a flashlight or radio. Neither the hand-crank nor the solar type works very well for recharging, the study found.
Assuming clear weather after a storm (which is a good bet for hurricanes, less so for blizzards), it will take one of the small solar chargers six to eight hours of sunlight to provide a 25 percent charge to an iPhone, the study found. The crank models don?t require sunlight, of course, just strong wrists. Very strong wrists, it turns out, capable of turning the crank at two rotations per second for long periods.
?A typical person will have to crank for 120 to 150 minutes at a steady pace to get a 25 percent charge on the iPhone,?? the study found. ?This may be a great option to keep the kids busy.?? (It took five or six minutes for each 1 percent of charge, the researchers found.)
The cranking required to run a radio or a flashlight embedded in the emergency device was more reasonable, the study found. Those devices often do not use as much power as a smartphone.
There is always the receptacle in the car where the cigarette lighter used to go. If the car battery is fully charged, it can give a 25 percent charge to an iPhone in 50 to 60 minutes, but in many cars, the circuit is not live unless the ignition key is turned to ?acc,? which may start up all kinds of other parts of the car and drain the car battery.
?If you turn on your car to keep the battery charged, make sure you are not in a closed garage,? the study also advises, adding, ?Gasoline is often precious during these times, so this may not be the best use of your fuel.??
A better bet, the institute found, may be battery chargers that hold AA or 9-volt batteries. It took the iPhone 30 minutes to go from a 0 to 15 percent charge using such a charger. Some AA batteries have a 10-year shelf life, the study noted.
And for larger devices? IPads were particularly finicky, the researchers found, often refusing to accept a charge from unusual sources like a hand-cranked generator. Galaxies and Kindles were somewhat easier to charge.
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