A 24-volt battery charger can be used to recharge a 24-volt battery, or it can be used to recharge two 12-volt batteries at the same time. To build one of these chargers a reducing transformer is required. It is used to reduce the 120 volts of alternating current of an output to a level of 24 volts of alternating current. This current is then fed through a rectifier that converts alternating current to direct current to charge the batteries.
Fix the transformer to one end 2 inches (5.08 cm) by 10 inches (25.4 cm) from the block. Connect a power cable to the two primary terminals of the transformer. This will allow the transformer to obtain power from an outlet.
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Fix the rectifier bridge on the wooden block. In a position 3 or 4 inches (7.62 cm or 10.16 cm) away from the transformer. Cut two 5-inch (12.7 cm) white cables and insulation strips 1/2 “(1.27 cm) from the ends of both cables. Connect one end of the black wire, first to one of the 24 volt terminals on the secondary side of the transformer. Connect the other end to one of the two alternating current terminals on the bridge rectifier. Next, connect the second cable to the second 24-volt terminal and the second terminal of the AC rectifier.
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Cut a piece of 5 inches (12.7 cm) of red wire and one of 5 inches (12.7 cm) of black wire. Strip the insulation 1/2 inch (1.27 cm) from the ends of both cables. Connect one end of the black wire to the negative terminal of the bridge rectifier, and connect one end of the red wire to the positive terminal of the bridge rectifier.
Place two large screws on the end of the block of wood. These screws should be about 5 centimeters apart. Connect the other end of the red wire to a screw, and connect the other end of the black wire to the second screw. These two screws serve as terminal connections for the battery charger.