Smaller than most of the keys in your pocket when folded away and weighing even less, the flexible Plan V opens to reveal a spot to plug in a 9-volt, as well as a microUSB port for connecting it ...

In a power outage, a 9 volt battery can give your phone enough juice to make a call or send a few texts. You may have seen this hack before , but it . Skip to Main Content.

The alarm will sound again if smoke continues to accumulate. The battery itself is the exact same size as a normal 9-volt battery—it has to be to fit in the devices it needs to power.

Not if you keep a 9-volt battery handy in your glove compartment. It's possible to revive a dead cell phone by using a 9-volt battery, along with something metal like a key, and your phone's car ...