Financial Model for a battery swap system

I need a financial model for a battery swap system for EVs. A user who owns an EV can drive to any of our battery swap stations to swap their battery. Each vehicle will need a battery swap at least once a day. They will pay a fee of $3 per swap but must pay a minimum of 10 swaps. Once they pay they will receive a smart card which has the number of swaps they have paid for on the card. Every time the use a swap, the number is reduced from their smart card. Please find attached the image of a smart battery swap system.