Flash charging your phone doesn't save money on electricity. Flash charging technology can provide faster charging speeds, but it does not change the energy consumption of the battery. Whether it's a flash charge or a regular charge, a phone battery needs the same amount of energy to be fully charged. Therefore, the use of flash charging will not reduce the electricity bill, just faster to full the battery. To save money on electricity, consider using more efficient chargers, managing your phone's power usage, and avoiding overcharging and frequent charging.
Charging technology and power consumption is completely unrelated, generally use increased voltage or current to achieve fast charging, power consumption depends on the use of the phone, such as open software, gps, wifi, brightness and so on