Charging Energy Added vs. Drawn
On your charges, you may see a figure describing the efficiency of the charge as a ratio of Energy Added vs Energy Drawn.
Energy Added refers to the net change (in kWh) in your battery's state of charge. Power Added is reported directly from the vehicle.
Energy Drawn refers to the amount of electricity that the charger used in order to deliver a charge to your vehicle; this is the amount of electricity you pay for on your utility bill. Energy drawn is calculated using the formula ((Amps x Voltage) / 1000) x Phases x Time. Because this is a time-based calculation if the vehicle goes offline during a charge the accuracy of this number may be reduced.
Over the course of a charge, some electricity will be "lost in transit" and it is completely normal to expect that the Energy Added value will be less than the Energy Drawn value. You should also expect to see the efficiency ratio change from charge to charge as there are a number of factors at play that can cause a "loss" of electricity.
These normal factors are largely beyond your control but may include:
- Energy lost in the form of heat within the charger, cable, and vehicle's wiring.
- Transmission efficiency due to ambient temperature and humidity.
- Energy used by the vehicle's onboard systems and therefore not directed into the battery (i.e. Climate Control, battery conditioning, etc).
- The state of charge of the vehicle.