Phone cases that supply extra battery power have been a new fad among mobile devices. There are many new choices that will give devices a longer charge via an external power supply enclosed in the case. Mipwr, a startup that is raising funds via Kickstarter, has a new take on a charging case: mechanical power. Their “Dynamo” case contains a lever that can be repeatedly squeezed by the user and will turn a magnetic dynamo (an electric generator) to supply more power. Mipwr estimates that a minute of manual lever-squeezing will equate to about 30 seconds of extra talk time on the device.
Here’s an article about Mipwr’s charging case: http://www.gizmag.com/mipwr-dynamo-iphone-charging-case/29235/