How To Hack A Flashlight For Emergency Power

Step 1: Flashlights

I found a great source of free emergency power: a hand crank flashlight. These are the flashlights that don't require batteries, and you just crank the handle to generate electricity, and it lights three bright LEDs.

I carefully took apart this flashlight to see what was inside. What I discovered was a small hand crank generator and some button cells that generate power. I decided to see if this would be enough power to fire up or charge my backup cell phone.

Step 2: Voltage/ Polarity

I found out that when you're cranking it, it will generate over 4 volts. So I took an old 12V car adapter that fits the phone, and I cut the one end off, leaving the end that plugs into the phone.

Then after checking polarity, I soldered the wires of the 12V adapter right to the two button cell contacts.

Then I cut a little notch in the plastic to fit the cable, and I sealed the whole thing up.

Step 3: Charging

Now let's plug the connector in and see if it will charge the cell phone. And sure enough, as I crank the flashlight, it's charging my cell phone; you can see the bars to the right. I was even able to charge my PDA. Now I've found a good source of free emergency power in a hand crank flashlight.