*4.4. Smart Billing System*

The billing system for electric vehicles is a central hub that manages the exchange of electricity between the charging station and the EV. This proposed smart billing system (SBS) has two entities: a power management entity and a communication entity. The communication entity can also exchange information with other entities using wireless communication. The power management entities reside inside both EVs and HCS. This entity calculates and reports the amount of power to be charged from both sides. After the charging is finished, SBS verifies the amount of charge that has been transferred and sends it to the blockchain server as a transaction. The operational flow of charging and billing is illustrated in Figure 5.

**Figure 5.** Operational flow of the billing system process.
