Consumer Reports: How to keep your cell phone battery alive
CONSUMER REPORTS -- Phone batteries always seem to run out when you need them! To the rescuesmart phone cases with a built in battery. The cases promise to protect your phone and add extra battery life. Consumer Reports tested four made for popular phones and found they all work well.
For the iPhone 5 or 5s, the $180 Mophie Space Pack almost doubled battery life. It also adds extra memory. And for Samsung's Galaxy S4, the $70 uNu Unity case also nearly doubled the phone's battery life. It is a little awkward to set up but you never have to do it again. The double battery life is there forever.
If you can't find a case that fits your phone, the Samsung Galaxy Portable Battery Pack can charge any phone that uses a USB cable, as long as you remember to power up the pack ahead of time. It costs $100.
And, if you can't get to an outlet or don't have electricity, Consumer Reports also tested some gadgets that actually generate power like solar panel Goal Zero Nomad 7 with a USB port. You can unfold it in the sun to restore power to your phone. It costs $80.
Also for $80 is the Goal Zero's Lighthouse 250 Lantern. Besides being a lantern and an emergency light, it has a large internal battery to charge your phone. When the Lantern's battery is spent, you can use its hand crank to power up your phone.
To conserve battery life when you're far from power. First, try lowering your phone's screen brightness and turn off auto-updates. Use the GPS sparingly. And, when there's no signal, put your phone in airplane mode. That stops it from trying to connect and turns off Wi-Fi, Bluetooth, and mobile connections.