kWh added is obtained directly from the TeslaFi API. It is calculated by the difference between the starting energy_added field and the ending energy_added field of the charging session.
kWh used by the charger is calculated by TeslaFi and not directly obtainable by the API. Each data point is calculated to obtain the kWh by using ((Amps * Voltage) / 1000) * Phases. If a connection problem occurs and a data point is missing, the missing point will be replaced with the last good data point. A charge that occurs with more than 10 missing data points will be indicated at the charging session that the data may be inaccurate.
Customer support service by UserEcho