A friend showed me this a couple weeks ago on his electric car, so I got one and just installed it on mine. It's a gizmo that monitors the AC power input to the charger, so you can easily look at the power consumed during charging. It includes a remote monitor display that connects wirelessly to volts/amps pickup units on the vehicle. This lets you keep the display unit in the house while wirelessly receiving data from the car.
The unit is made by efergy, and is really meant for monitoring electricity usage at a house level. It's meant to be installed inside the service panel where electricity comes into the house.
However, in an electric vehicle, whether it's a car or motorcycle or scooter or bicycle, there is a spot in the charging circuit just before the charger where you can measure AC power going into the charger. This is where you install the data telemetry unit.
This is the unit where electricity goes into the charger on my car. It's a pair of NEMA 14-50 sockets and plugs, as well as a 5-20 socket because I do need to plug in a couple normal gizmos while the car is charging. For plugging into various power outlets I might find, I have a variety of adapter cords to convert from 14-50 to other kinds of outlets.
This is the box .. nice box
These are all the components of the system.
Note the AA batteries. I'd rather have these units plug into AC outlets to power themselves rather than having yet another gizmo in which to keep AA batteries installed. Sigh.
These are the sensors to detect AC voltage and current. They clip onto the power cable and then connect to another box that transmits data.
This is the sensors attached to the two hot lines on the power system.
AA batteries installed
The transmitter unit connected to the sensors.
There's a simple dance to get the two units (the transmitter and display panel) paired with each other. Once paired the display panel shows kilowatts of power detected by the sensors.
It also shows the $$ cost of that power - once you've configured it with the cost/kilowatt-hour.
It also shows the carbon footprint of that power - once you've configured it with the carbon impact of your electricity. I wonder how you find that number out.
It also shows kilowatt-hour consumption per day. This isn't ideal, for an electric car owner, because you'd really want kilowatt-hour consumption per charge session.
You do have to configure the unit with the voltage, and I believe this sort of sensor can only detect amperage and not voltage. It means that - if you only charge your vehicle on one voltage then the display unit will always show the correct kilowatts. If you charge at different voltages at different times, you'll have to adjust the display unit settings. I usually charge my car at 240 volts but sometimes at 120 volts depending on the power available wherever I go.
Installation was pretty simple and the unit - so far - seems simple to use while providing useful data.
I believe this could be installed on a commercially built manufactured electric car. You'd simply have to locate the J1772 port and identify which wires coming out of that socket correspond to the two AC hot wires. With luck those wires will be available to clip on the sensor units.