One of the questions I seen online this week was from a person who was going to be taking a work vehicle home each night. That vehicle was an EV.
This meant the business would be paying for the power to recharge the vehicle, which raised the question, how would you log the power use from the outlet used to charge the EV?
Given this may be a scenario many of you face in the future, I decided to take a look at the options available.
As you’d expect, the sophistication of the solution depends on the convenience of the solution. If you want the power usage to be logged and have the ability to check that usage from a mobile app, then you’ll need to connect the device to WiFi. In my garage, the WiFi signal is strong so there’s no issue, however with apartment buildings, things get a lot more complicated.
The best solution
In the event money is no option, the best solution I tracked down is… The Efergy Ego Smart power Socket & App. This normally costs A$69.95 but is on special for A$39.95 (+$9.95) right now online from Reduction Revolution.
Not only can you measure the energy supplied to the device (in this instance a car), but you can also turn it on/off using this device, or even schedule timers to do that automatically. This means you plug in the car when you get home, but only start charging during off-peak times to save you (or your employer) money.
This works by monitoring the power that moves through the unit and logs that data in real time to the Efergy servers online. You can then consume that data on-demand, or export a .csv file on-demand.
One of the neat features is the ability for the app to monitor and control additional outlets, as many as 20. This is great when looking to the future as some homes may well have 2 EVs in the garage, connected to separate outlets. Each outlet can be named, helping ensure the report is for the right vehicle.
The budget solution
One cheaper option is to use a more basic power monitor and read it each quarter. You’d need to manually record it somewhere before resetting at the start of the next usage period. This introduces some opportunities for things to go wrong, like the event you are away from home at the end of the period. You would also need to ensure your employer was happy to trust you the data is correct, if not, perhaps a photo of the reading would suffice.
When we look at this level of monitoring, it’s a fairly similar requirement to that of Bitcoin miners who monitor their power use carefully to determine the profitability of mining. With a power monitor that sits between the outlet and the charging plug, the other big consideration is a power outage. If you lose power to the power meter, your reading may be lost unless it provides a decent battery backup.
The bugdget solution I would recommend is the Arlec Energy Cost Electrical Meter, available from Bunnings for just A$19.90.
These two solutions are based around the EV charging being done from a standard 240v outlet. With some electric vehicles, like Tesla’s, there are other charging options, like the higher powered wall charger. This moves the power source from a single phase 10A outlet, up to a 32A, increasing the charging rate from 15km up to 50km per hour. That does require an electrician to install and would mean you need to seek a different alternative to track usage.
When I reviewed the Tesla Model X, I wrote about the cost of charging by measuring my standard daily average consumption, then comparing to the days I charged the car. This only works if you’re measuring it to estimate how much the EV is costing you, but the devices above are a significantly more accurate way to do it and certainly what you’d need to convince the boss to pay the bill.