It is usually a good idea to have more amps in the PS than what you are charging at. Some chargers will not charge at 5 amps with only a 5 amp power supply as some of the energy must be used to power the different functions on the charger. Plus having a higher amp PS gives you more options in the future in case you want to run a 2nd charger at the same time or a tire truer. You never know what the future holds