How to Make Your Own Battery-Powered Gadget Chargers

• batteries
• chargers
• gadgets
• electricity
• survival
• DIY
• projects
• cellphones
• laptops
• cameras
• iPod

1. A paper clip acts as an On/Off switch. Just remove one end from the battery tray’s metal contact to kill the current.

2. Clip the battery tray’s red cord to the phone battery’s positive metal contact, and the black cord to its negative one.

3. The DIY charger has no way of limiting the current or preventing overheating. So limit it to 10-minute charges, and unplug it if it starts to get hot.

There’s no magic to a cellphone charger. It’s really little more than a plastic-wrapped strip of copper wire designed to deliver power (stepped down in voltage and converted to DC, of course) from an outlet to your phone battery.

So if an emergency strikes and you find yourself without either your charger or a working wall outlet, it’s really pretty easy to macgyver together a contraption that uses AA batteries to quickly give your phone enough juice to make a few emergency calls. The whole process, which is a lot like a miniature version of jump-starting a car, takes minutes and uses parts that can be found at Radio Shack for a total of less than $5.

To do it yourself, you’ll need the following: a few AA batteries, a four-AA-battery tray, a metal paper clip and two alligator clips. That’s it, and the finished product should be able to charge just about any phone (with the notable exception of the iPhone, which does not have an easily removable battery) if you find yourself in the wilderness or waiting out a power outage.

Check the Voltage

The first step is to check the voltage on your phone battery. Most clock in at about 3.7 volts, but you should pop it out of the phone and read the fine print to see for sure. This information will let you calculate how many AA batteries you need. The key is to use enough to barely exceed the phone battery’s voltage—employ fewer and you won’t be producing enough juice to charge the battery, but hook up too many and you could burn out the whole thing. AA batteries are 1.5 volts each, so charging a 3.7-volt battery requires combining three of them for a total of 4.5 volts.

Pop the batteries into the AA tray. It’s a four-battery tray, so you’ll need to put something else in the last AA slot in order to complete the circuit. This is where the paper clip comes in handy. Unfold it and hook one end through the metal spring in the negative end of the empty slot. Then take the other end and bend it so it touches the metal contact on the outside of the tray at the positive end of the same slot.

This clip will act as a sort of On/Off switch—as long as it is touching both the spring and the metal contact, power will be flowing and the charger will be on.

To turn the charger off, simply move one end of the paper clip away from one of the contacts.

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