Yes, you can fit a new alternator yourself. However, you should not attempt the process unless you are experienced and know what you are doing. Not only can you cause extra damage to your vehicle, but a live battery can also be very dangerous if you don’t disconnect it properly.
To fit a new alternator yourself, you must follow this process:
Disconnect the battery. You must disconnect the terminals in the right order and ensure it is completely disconnected before continuing.
Disconnect the wires from the back of the alternator. Label the wires as you go so you can reconnect them all in the right place.
Remove the belt from the pulley.
Remove the bolts. These connect the alternator to the bracket. Once these are loose, you are then able to get the old alternator out of the car.
Make sure you have the correct replacement alternator. The last thing you need is a part that's too big or too small.
Reverse the removal steps to install the new alternator.