How to charge an Electric Vehicle at home

A Comparison of Power Outlets, Basic EV Chargers and Smart EV Chargers 

Electric vehicles (EVs) are becoming increasingly popular due to their environmental benefits and cost-effectiveness. However, the method you choose to charge your EV can significantly impact these advantages. In this article, we will explore the differences between charging an EV using a power outlet, a basic EV charger (aka Dumb Chargers) and a Smart EV Charger.  

Power Outlets vs. Basic EV Chargers vs. Smart EV Chargers 

Charging an EV from a regular home outlet can easily take more than 24hrs depending on the size of the EV battery. This can be a nuisance if you need your vehicle ready tomorrow morning or making the most of overnight / off-peak tariffs. If you are not using a dedicated outlet or the wiring in your home is old or damaged, there is also the risk of fire damage due to the continuous high-power draw over many hours. Still, this configuration might work if you use your EV on an occasional basis. In this case, a dedicated power outlet (10 or 15A) and a portable/trickle charger might do the trick for you, as you will be adding between 10-20km of range every hour.  

If you use or are planning to use your EV on a regular basis, a home charger would be a much better option. These chargers use a dedicated circuit, like electric stoves and clothes dryers, and can charge a vehicle in hours instead of days. These chargers can deliver 32A of current and are generally available as a single-phase, 7.4kW; or as a three-phase, 22kW device. This means that you will be able to add between 40 to 100km of range per charging hour, depending on the size of the battery of your EV and your electrical installation. 

Do you really need a three-phase / 22kW charger? 

First, this will depend on your electrical installation at home. If in doubt, check with your electrician. Something that is often overlooked is the speed of the onboard charger in the EV. Tesla EVs, for example, are equipped with an 11kW onboard charger. This means that, even if you have a three-phase electrical installation at home and a 22kW EV Charger, the charging speed will be limited to 11kW. In the case of BYDs the onboard charger speed is limited to 7kW so, even if you have a three-phase electrical installation at home, we recommend installing a single-phase 7.4kW charger in one of the lines.  

Is it worth investing in a Smart EV Charger? 

While many of the home EV chargers offer simple plug-and-play functionality, Smart EV Chargers take things further with a range of connected features that allow owners to manage and monitor their vehicle’s charging session remotely: 

• Smart phone app: usually allows you to control your charger remotely (think start, stop, pause, lock/unlock), set charging schedules and check your charging statistics and estimated costs. The charger’s connectivity is likely to offer Over-the-air (OTA) updates for additional features or app improvements in the future.  

• Load balancing: considering the electrical current used by a Level 2 EV Charger (32A in most cases), this might cause a constraint in some homes, especially if other high-drain appliances or devices are used at the same time. Load balancing allows to derate the EV Charger to prevent the fuse from tripping and suffering a blackout. The beauty of load balancing is that, once other appliances are turned off and home capacity becomes available, the current through the EV Charger is ramped up again so you can charge at the maximum available speed. Notice that an energy meter or CT clamp will need to be installed in your switchboard to enable this feature. All Ohme chargers come with a CT clamp in the box.  

• Solar compatibility: if you already have solar panels or planning to install them soon, future-proofing your home with a Solar Compatible charger is a no-brainer. Why pay for the electricity from the grid if you could use your excess solar power to charge your EV? In a different article we will explore how much you can save in each State/Territory when charging your EV with solar energy.  

Smarter, Greener, Cheaper 

At Ohme we believe in charging the future in a smarter, greener and cheaper way. How does this translate into our EV charging solutions? 

• Integration with Tesla vehicles: this feature allows you to access the state of charge of your Tesla and other specifications (range, battery size, etc.) to simplify your charging routines. In the example below, the user has entered a target state of charge of 80% and a departure time of 1.28pm. That’s all the information we need, their Ohme will take care of the rest. Stay tuned for more updates as we plan to extend this feature to other EV makes soon.  

• Dynamic Tariff Integration: Ohme allows you to select your electricity tariff when setting up your charger for the first time or change it if you are moving to a different supplier. You can then forget about your off-peak and peak hours, the Ohme App will only charge your EV when it is greener or cheaper, according to your preferences. You can even set a price cap to ensure that you never charge over that price or override this setting altogether if you need to charge in a hurry. For example, charging a Tesla Model Y Long Range with an 81kWh battery on a full charge with an Ohme smart charger on an off-peak tariff, such as OVO’s The EV Plan, could cost just $6.48. Source: OVO The EV Plan at 0.08c/kWh. This is a unique feature available with Ohme Chargers. 

Here is a comparison table outlining the features typically included in each type of home charging method: 

In conclusion, the method of charging your EV can significantly impact both the cost and environmental benefits in the long run. Even if Dumb/Basic EV Chargers might be cheaper to begin with, Smart EV chargers offer a range of features that provide convenience and efficiency, while solar charging and dynamic tariff integration with electricity suppliers can deliver substantial cost savings in the long run.  

As the popularity of EVs continues to grow, these considerations will become increasingly important for potential and current EV owners. 

On a final note, please remember a licensed electrician will be required to install a level 2 charger. 

Happy Charging! 

Xavier Peña is the Head of Partnerships at Ohme Australia.