In some cases the energy consumption report from your car can be different from the energy consumption report generated by the Easee App.
The main reason for this is where the data is collected.
- The Easee App collects the use data at the charger.
- The car collects the use data as it is given to the car battery.
This is usually a very small difference, but if you think about the long-term use, then those micro-differences can add up.
That's good to know, but why is it different?
This is more than because the distance the energy travels, or because of resistance in the wires. All homes and offices, all electric grids are AC. AC travels farther with less loss than DC. Cars (and computers, and cell phones and so forth) run on DC power because it is more efficient at very short distances. The car's on-board charger converts the AC energy to DC for storage on the battery, and this conversion itself requires using some of the energy.
Again, this is a very small amount, but when you look at reports over a car's lifetime then the small differences will add up. It is hard to give precise numbers, but the conversion from AC to DC (or in fact from a high voltage to a low voltage) results in as much as a 15% loss due to the conversion. In physics there is no free energy, so some of what passes through the Easee charger will be spent at the converter inside your car.
This results in lower consumption values when they are compared, because the charger reports the amount of energy it has sent to the car, and the car reports the amount of energy it has received to the battery - that is, after the conversion to DC.
So if you compare your car's reports to the Easee reports, you might find a discrepancy as large as 1 amp.