USBattery

Cut off the plastic wrapper that covers the dead AA battery, taking care not to score the metal underneath. Depending on the brand, you might need to clean glue from the battery case using a label remover.

Some batteries (Duracell, for example) have a small indent in the case near the negative terminal; make cuts here with your hacksaw. Don’t cut through the battery with a single cut. Just pierce the outer case, then rotate the battery, making a series of small cuts.

CAUTION : Wear gloves and goggles when cutting and emptying the AA alkaline battery.

Remove the end cap of the battery, using pliers if necessary, and save it for later. The inside is filled with chemical mush. Scoop this out and dispose of it safely. Wash the battery in cold water to get rid of any remaining mush.

Hold the battery in a cloth and use either a drill or a countersink to carefully and slowly grind out the carbon. A 12mm bit should fit inside the battery quite neatly. Stop every now and again to empty the carbon dust out of the battery casing.

CAUTION : If you drill too fast, the casing will get too hot to hold, or the drill will clog with dust and snatch the casing from your hand.

When the casing is empty, wash it again and clean it with a piece of cloth on a screwdriver. Carbon dust is electrically conductive, so you don’t want to leave any in there to short out the USB circuitry.

The plastic case on most USB thumb drives is clipped together and can be opened fairly easily by levering around the seams with a knife.

The space inside the battery is tight, so you may need to file the edges of the USB circuit board and gently flex the metal casing to get it to fit. Just be careful not to knock any components off. Also look out for any “through-the-board” links, and make sure that you don’t grind them away.

The standard USB plug is too large to fit inside the battery, so it needs to be removed with a soldering iron or a micro heat gun. Heat the solder as evenly as possible, without melting any of the surfacemount components. Don’t pull the socket; applying too much pressure will break the fine metal tracks on the circuit board.

The wires should be connected as shown in the diagram. This will take a steady hand and plenty of patience. If you have a magnifying light, you might want to use it. Begin by applying solder to the wire and the socket individually, then put them together and touch them with the iron to briefly remelt the solder. Holding the iron on for too long will melt the socket. Once the wires are soldered in place, strengthen the joint by applying a little epoxy resin to the back of the socket.