Hi

Plastic cover ontop of battery where alternator cable connects to battery has melted around the area where the alternator and other black cable is beside it.These wires are getting too hot.I have fixed the link at battery where alternator wire connects and it charges fine but the wire beside it still gets too hot.This wire seems to run from battery to inside of the car.Are there any common issues I should look for?

Thanks

make sure all the terminals are not corroded, corrosion = resistance = heat

it might mean undoing stuff to check