Alternators perform an important function in the running of your car. Your car battery starts your car, but as soon as the engine is running the alternator takes over and powers all the electrics you need. It also recharges your car battery. Most cars have a 12-volt battery but your alternator will have a greater output than 12-volts, due to the electrical requirements of modern cars. Alternators vary in output and are usually in the region of 15-volts, but if your car has additional electrical items that require greater usage from your alternator, then wiring a 24-volt alternator is a sensible idea.
Disconnect the negative and positive battery cables from your battery using a wrench. Tuck them safely away from the battery.
Look at your 24-volt alternator to determine the positive and negative terminals. This is important, otherwise you damage the alternator and the vehicle's electrical system.
Loosen the terminal fittings on the alternator. Do not undo them too much. Depending on the alternator, it could have screw fittings or you will need an appropriately-sized wrench.
Connect the negative black cable attached to your car to the negative terminal of your alternator. Ensure the connection is tight and secure.
Connect the positive red cable that goes to your battery and other electrical systems to the positive terminal of the alternator. Ensure the connection is tight and secure.
Reconnect the negative and positive battery cables to your battery and your 24-volt alternator is ready to operate.