Crank Charger

Project Number: 1

Description: Build the circuit shown here and set the meter (M6) to the 5V setting. The meter will measure about 3.6V if the battery is charged up. Turn the hand crank (HC). The yellow LED (D5) comes on when you crank fast, indicating that the crank is charging the battery. If the battery needs to be recharged, you can use this circuit to charge it.

Snappy: Although the battery is rated as 3.6V, it may charge to as high as 4.0V. If you are monitoring the voltage using the meter, you may see the voltage quickly reach 3.6V, but this does not mean that the battery is fully charged. When the battery is discharging to power something, the voltage is nearly steady for a long while then drops off quickly. The same thing occurs when it is charging. Recharging the battery will quickly reach around 3.6V but it needs much more charging to avoid a quick drop-off when discharging.