The electric vehicle industry in Australia is rapidly expanding. With over 9,680 EVs sold across the country just in the first half of 2022, the EV industry is growing at full speed. In the next decade, you will likely have an electric vehicle and you may already be looking at buying your second one.
If you already have an electric vehicle, then you know that having an EV charger is important to achieve fast charging. However, if you have two EVs, then it becomes even more important. The question that remains is, will you need a second charger? In this article, we will address this and more interesting facts related to the subject to let you know the best approach.
Figure 1: EV Charging At Home. Source: BIVAs the EV industry expands, more electric vehicles will be in our homes.
There are 5 main solutions that you can explore if you want to charge two or more electric cars, as can be seen below.
Installing two separate EV charging stations like the 7.2kW Ocular LTE is one of the most desirable ways to charge two electric cars at home. This not only allows you to charge two EVs simultaneously, but it also allows you to charge them at full power in just a few hours.
However, the downside of this solution is that it is not cost-effective. Installing a second charger may add an extra $1,000 to your EV charging costs and you may only use them simultaneously on some occasions. Limited electrical capacity can also prevent you from installing a second level 2 charging station since many houses may not have enough electrical infrastructure to feed two 7.2kW charging stations (most only have current infrastructure to install one charger).
Figure 2. Ocular LTE. Source: Ocular Charging
Another alternative to consider is installing a dual EV charger. This type of charger includes two cable cords that can be used to power two vehicles simultaneously while using the same electric circuit branch. This type of charger maximizes the available electrical capacity to charge the two EVs, optimizes space, and potentially avoids the need for electrical upgrades.
Nevertheless, there is a disadvantage. The dual EV charger splits the available power in the circuit into two parts. In other words, when charging two EVs simultaneously, a 7.2kW level 2 charging station will charge each EV at 3.6kW. This reduces charging performance and duplicates the standard charging time that you would need to fully charge each vehicle.
Figure 3. Clipper Creek Dual EV Charger. Source: Clean Technica
Another valuable option to consider is to install two EV chargers that have integrated power sharing capability, like for instance the Tesla Gen 3. This refers to the capacity of an EV charger to communicate with other similar charging stations to manage the electrical capacity available and distribute it properly among connected electric cars. This technology works by establishing one of the chargers as the leader and the other(s) as the follower(s).
Figure 4. Tesla Gen 3 Charger. Source: Ezoomed
Let’s understand this better with an example. Let’s assume that the available electrical capacity in a house for EV charging is 55A and that there are two 40A circuit breakers for available spares.
If you choose to install two 7.2kW separate EV chargers (one per each circuit), there is a risk that when charging two EVs simultaneously on full power, the maximum 55A available for the home will be exceeded. This could result in tripping the main circuit breaker of the house and result in a poor performance charging experience and installation.
Meanwhile, if you choose a dual charger, you will only be able to use up to 32A for the charger, which will also be split into two parts, resulting in much longer charging times.
On the other hand, installing two EV chargers with power sharing capability and connecting each one to separate circuit branches, would allow you to set up a maximum current demand of 55A for the two charging stations. This is done via Wi-Fi or direct communication between the EV chargers and allows you to control the maximum demand current to establish it within safety limits. Additionally, this allows you to maximise the use of the existing electrical capacity to reduce charging times.
Figure 5. Two Tesla EV Chargers with Power Sharing. Source: Tesla
Another similar alternative to power sharing is installing two EV chargers with load balancing capability. Although similar to the third option as mentioned above, this type of charger allows you to efficiently manage electrical demands with other loads of the house, not just EV chargers. Two examples of this type could be the Zappi 7.2kW or the 7.2kW Wallbox level 2 chargers. You can shop our chargers on our store page.
The main difference, in this case, is that you will need to install a separate energy management unit, likely known as the load balancer. This will need to be installed by an electrician.
Figure 6. Wallbox Load Balancing Feature. Source: Wallbox
Let us better understand this feature through an example:
Let us assume that you have an 80A max power input installed at your house and that you want to install two 7.2kW Wallbox EV chargers to power two or more electric vehicles at your home. Under normal conditions, the Wallbox would draw about 32A each. By having two EVs connected you would have 64A being drawn from the power supply of your house at a single instant, leaving about 16A left for use.
But, as you begin to turn on other appliances in your house like dishwashers, washing machines, dryers, microwaves, iron, and TVs etc, you are likely to exceed the 16A that you have left for use. If you were connecting just two regular EV chargers, then you would most likely be exceeding the maximum rated capacity of the feeder and be tripping the 80A circuit. This is not only unsafe but also provides a poor charging experience.
On the other hand, by using EV chargers with load balancing, you would be able to use all the regular appliances that you want at your house while continuing to charge the EVs safely and without the risk of tripping the circuit. Under this case scenario, the load management system would prioritise the appliances of the house to be powered safely and use the remaining amps available to power the EVs.
Let us say that by using your home appliances, you were drawing 35A at a single instant, this would mean nearly 45A would be left available for EV charging. The load management system would distribute this remaining amperage among the two EV chargers, either equally or proportionally depending on the state of charge of the vehicle’s battery.
In the figure below, we can see an example of this feature for a case where a single EV charger with load balancing is installed.
Figure 7. Load Balancing Feature. Source: ZJ Beny
Finally, the last option is to install a three-phase EV charger. Three-phase EV chargers generally have a maximum charging capacity of 22kW which allows you to charge an EV very fast. Although you may not be able to charge two EVs simultaneously, you will be able to fully charge each electric car in as little as 3 hrs in some cases (depending on the car battery). This means you could fully charge two EVs in a single day (one at a time, but very fast for each car you charge).
The downside is that generally, only large houses have a three-phase system installed. Most houses use a single-phase electrical system and upgrading to a three-phase system is in most cases not technically or financially feasible. Again, you’ll likely need an electrician to assist you here with any electrical upgrades. Several manufacturers offer three-phase EV chargers including some versions of the previously mentioned chargers such as Zappi, Wallbox, Ocular, or Tesla.
Figure 8. Zappi Three-Phase Charger. Source: ZappiWhile adding a second EV charger to your house is a good choice, it is not always necessary. If you have only two electric vehicles, consider the following factors before purchasing a second EV charger:
On average, an Australian car travels about 37 km per day, while the average electric car range is about 313km. Based on this data, an electric vehicle does not need to be recharged daily.
This means that if you have two vehicles at home, you could alternate daily charging between the two EVs while using a single level 2 charging station.
The standard level 2 charger for home is rated at 7.2kW. This means that a 2022 Tesla Model 3 Performance car that has an 82kWh battery and a 547 km range would take about 12h to get fully charged using a single level 2 EV charger. If you have two Tesla Model 3 Performance vehicles at home, this would translate into roughly 24h total charging time for the two vehicles.
This may sound like a lot, but when you consider the 547km range, the electric vehicle could travel for days using a single full charge. Adjusting your driving habits to charge the vehicles during days off or simply overnight could avoid the need to get a second charger.
Evaluating the existing electrical infrastructure of your house is an important factor to consider. If your house has a single-phase connection (which probably will) then you must consider only single-phase chargers. You can get your house upgraded to 3 phase power, but this will be a costly exercise by an electrician. Assessing how many spare circuits you have for EV charging is also important. Keep in mind that a 7.2kW level 2 charger demands about 32A, so if you only have a single 40A branch circuit, then installing two chargers may not even be possible without upgrading the main panel, which can be costly.
Assuming that you have two EVs, if only one of the cars is used daily, while the other one is used just occasionally and for short distances, then a single charger can easily do the job.
If both vehicles are used daily, then using the level 2 EV charger to charge one of them, while simultaneously charging the other vehicle with the level 1 EV charger that comes with the car could save you time. Level 1 EV chargers use low power ratings of 3.6kW or less, therefore, it will take many hours to charge a vehicle, but it will give some charge to the second vehicle until the first car is fully charged with the level 2 charger.
Figure 9. Supplied Level 1 Charger.
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