Supercharge Your Home: Ultimate Guide To Charging Multiple EVs

If you’re living in a household of multiple EV owners or looking to the future where this may be the case, some planning will go a long way to ensure no one runs out of juice.

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This guide offers an overview of the current options to keep every EV charged without sparking any tensions.

The primary methods for charging multiple EVs at home include:

1. Sharing a single charger.
2. Utilizing two.
3. Employing two with load management.
4. Implementing a multi-port charger.

Each method involves various approaches and a wide range of hardware solutions. Factors influencing your choice may include electricity supply type and capacity, Distribution Network Service Provider (DNSP) regulations, budget constraints, vehicle model, battery size, charging time, and individual priorities.

1. Sharing A Single Charger

Admittedly, you likely started reading this article seeking more sophisticated solutions than simply taking turns with a single EV charger. However, this may be the only viable option for some households due to electricity supply constraints or DNSP rules.

If you’re stuck with being a single-charger household, it’s not the end of the world. Think of the money you’ll save on hardware.

Sharing is Caring

Everyday charging may not be necessary for every household member. Factors like battery size, charging times, and commuting distances will vary. Many families can successfully coordinate a sharing schedule, alternating usage on different days.

Maybe that doesn’t work for you. You’re rightly sick of jumping out of bed in the middle of the night and shuffling vehicles around to reach the charger. Considering there’s no standard for charge port locations on all the different EV models available, it doesn’t seem like a good long-term solution. There’s got to be a better way.

2. Using Two Chargers

Using Two Level 1 Chargers

When installing a second or even a first dedicated charger isn’t feasible, consider having an electrician install two 15A General Purpose Outlets (GPOs) in your home. This would enable you to plug in and use two Level 1 chargers simultaneously, with each operating on a separate circuit.

Opting for this solution can be quite effective, as a 15A GPO can accommodate up to 3.6kW. With two outlets, you’ll achieve a combined power of 7.2kW—comparable to most single-phase Level 2 chargers shared by two EVs.

Using A Level 2 Charger Plus Level 1 Charger

One option is to charge an EV using the dedicated Level 2 charger while the other vehicle uses the Level 1 device that came with it, plugged directly into a power outlet. Though the second vehicle experiences a slower charging rate, this setup allows for simultaneous charging of both vehicles.

Potential Pitfalls

The level 1 slow charger is not a smart device. It will draw whatever current the EV requests, and the only way to adjust the charge rate is via the car settings. This means the Level 1 charger could operate at near the full rating of a 10A or a 15A GPO the whole time it’s plugged in. This potentially strains the circuit which, unless you take a few precautions, can lead to problems. And surely it goes without saying, but I will anyway – never plug two into the same power outlet, or even the same circuit.

The other thing to consider – if you’re charging two EVs simultaneously, the current draw starts to add up. For most households running a level 1 and level 2 EV charger at the same time is not going to overload the main switch (yet), but add a few more high-powered appliances into the mix and it starts to look a little different.

For example, a single-phase level 2 charger is rated at 7.4kW (up to 32A). Add that to a level 1 charger running at full tilt on a 10A circuit (assume 10A). It’s now potentially at up to 42A just for EV charging. A typical single-phase main switch on a domestic switchboard in Australia is rated at 63A or 80A, so this could account for over half your electrical supply. You’re now at the point where you need to know what other power-hungry appliances are running, otherwise risk tripping circuit breakers.

Having a nice big rooftop solar array and charging your vehicles during the day can reduce grid demand substantially. But this is no panacea because the sun isn’t always shining, and electrons go where they want when they’re needed.  Even if your charger can be configured to only charge from excess solar energy, it is still capable of full charging power with no sun. Your electrical installation has to be up to the task for the worst-case scenario.

With a three-phase supply, spreading the load across all three phases is easier. It’s possible to have a single-phase level 2 charger installed on one phase, while other loads are balanced accordingly across the other phases. The downside is that a single-phase device could take longer to do the job than a 3-phase charger. Although it gives you more headroom on the other phases, it may not be the best option if fast charging one vehicle is your priority.

3. Using 2 Chargers With Load Management

OK, here’s the part you’ve been waiting for. If you own two electric vehicles, it makes sense to have two EV chargers right?

Yes, of course; however, the ramblings above (Potential Pitfalls) are now more important because you’ve upped the ante as far as potential loads on your switchboard and wiring. The number of EV chargers you can install is limited by the capacity of your electricity supply for all the reasons above. As always, your DNSP has the final say on this, based on Australian Standards and relevant State electricity regulations.

The clever people designing and building EV chargers have devised solutions to address maximum current limits on typical household supplies. Enter “load management”. They’ve worked out a way to keep your wiring and switchboard happy by using smart devices to manage the amount of current draw available to each unit, and to prevent overload of the system. This is generally done one of two ways:

Power Sharing

Some chargers can be configured to set a maximum power limit that is shared by all installed chargers. Power sharing (sometimes called load sharing) is achieved by using a smart device that communicates to all configured devices through Wi-Fi, Ethernet, or Open Charge Point Protocol (OCPP).

For example, if your main switch is rated at 63A, a limit of 40A could be set for 2 chargers to share, leaving 23A for household appliances. The user, however, would have to manually monitor the household loads and make sure they are under the threshold, otherwise risk overloading the main switch.

Dynamic Load Balancing

Other chargers use a feature called dynamic load balancing that takes additional loads into account as well. This is useful if you have no choice but to put a load of washing on while charging up the EVs.

Dynamic load balancing considers the electrical capacity of a household on a real-time basis. It adjusts the charging rate accordingly, ensuring it stays within the available power capacity at any particular time. Household loads are given priority. You can now sit back with a smile, knowing that your house won’t trip the main breaker now that you’ve relinquished control to a computer.

Some devices with dynamic load balancing can also interact with solar inverters, so they incorporate instantaneous rooftop solar energy into their algorithm.

Regardless of whether or not your EV chargers have any of the above smarts, in the case of multiple single-phase chargers it’s recommended to install them all on different phases if you have a three-phase supply, to spread the loads. If you are on a single-phase supply your options are more limited.

DIY Solutions

Home Assistant

For tech-savvy people with too much time on their hands – Home Assistant is an open-source home automation platform that allows you to control various smart devices, including EV chargers. It’s possible to control two EV chargers with the app and operate them one at a time or limit the current on each. To control two EV chargers with Home Assistant, you’ll need two compatible devices that support integration with either OCPP or Modbus protocol.

Once you have connected the chargers to your home network, you can integrate them into Home Assistant using the appropriate add-on. It’s possible to create automations or scripts that allow you to operate them one at a time or limit the current on each.

For example, you can create an automation that starts charging on one EV and then switches to the other once the first one is fully charged. You can also create scripts that allow you to set the charging current for each charger individually.

IFTTT

Another DIY solution is IFTTT (If This Then That), which is both a free web-based service and a mobile app that allows users to create and manage automated tasks. The app allows users to browse and enable pre-built applets, create their own applets using a simple drag-and-drop interface, and manage their connected services and (supported) devices.

If your EV chargers support power sharing, you may be able to use IFTTT in conjunction with a smart home automation platform to automate the process. For example, you could use IFTTT to trigger a smart plug or switch to turn off or reduce the power to other appliances in the house when the EV chargers are in use, ensuring enough power is available for both.

Third-Party Apps

An ever-growing range of third-party apps can be integrated with Home Assistant, IFTTT, or communicate directly with EV chargers and devices. These have varying levels of functionality based on supported hardware and communication protocol. Unfortunately, there’s no one-size fits all.

Some of them, although not designed specifically for charging multiple EVs, may help optimize your  experience: For example: Charge HQ, EV Energy, and Homeseer.

4. Use An EV Charger With Multiple Ports

Seemingly an obvious solution for charging two EVs is a device with two ports, so you can simply plug in any vehicle whenever you want.

As of the time of writing, sadly, there are no dual port EV chargers available designed specifically for homes, which are available from retailers in Australia. I guess there aren’t enough dual EV households here yet.

For more dual power control system for electric vehiclesinformation, please contact us. We will provide professional answers.

You can still buy a dual-port EV charger designed primarily for commercial and public use. It might not be the most cost-effective solution, but as long as you comply with your DNSP regulations, and have sufficient electrical supply infrastructure, nothing is stopping you from installing one in your home.

Which EV Charger Is Best For My Growing EV Collection?

I can’t tell you that. I can, however, point you to our EV Charger Comparison Table where you can compare prices and specifications side-by-side and see what solutions may be best for your situation and budget.

Also check out another SQ article – Best EV Chargers : According To Australian Installers. All top 3 chargers on this list can be configured to suit multi-EV households, although they may need additional hardware.

Hopefully I’ve given you enough information to make a decision that’s right for your circumstances.

Main content:

The electronic control technology of electric vehicles is mainly composed of sensors, electronic control units (ECUs), drivers and control program software. Although there are certain differences in the electronic control system in different types of electric vehicles, in general, it generally includes energy management control, chassis electronic control, body electronic safety control and vehicle control technology.

The energy management system is one of the core components of new energy vehicles such as pure electric vehicles, hybrid electric vehicles and fuel cell vehicles. It is mainly composed of three parts: power distribution, power limitation and charging control. Its working principle can be simply summarized as: the electronic control unit analyzes and processes the data according to the battery status information and other related information collected by the data acquisition circuit, and forms the final instructions and information to send to the corresponding functional modules.

The functions of the energy management system include:
①Maintain the work of all battery components of electric vehicles and keep them in the best condition;
② Collect the operation data of each subsystem of the vehicle for monitoring and diagnosis;
③Control the charging method and provide the display of remaining energy.

1.Energy management and control of pure electric vehicles

In a pure electric vehicle, the power battery pack serves as the only power source to drive the motor to rotate to make the vehicle run. When the capacity of the power battery pack is low, it can be charged by the on-board or external charger to supplement energy. Pure electric vehicles also have the function of braking energy regeneration control. The flow of energy in a pure electric vehicle is shown in Figure 1.

Figure 1 Schematic diagram of energy flow in pure electric vehicles

2.Energy management control of hybrid electric vehicles

Hybrid electric vehicles can give full play to the advantages of internal combustion engine vehicles and electric vehicles by combining the engine, electric motor and energy storage device (battery), etc., and perform good matching and optimal control of them, thereby avoiding their respective shortcomings. During the driving process of the hybrid vehicle, the function of its control strategy is to use the hybrid vehicle according to the performance characteristics of the powertrain components and the driving conditions of the vehicle under the premise of meeting the basic performance requirements of the vehicle driving. The energy-saving mechanism of the design gives full play to the energy-saving potential of the design scheme, so that the vehicle can achieve the target performance in terms of fuel homogeneity and emission. The energy management control strategy is the technical core and design difficulty of the research and development of the hybrid electric vehicle, and it is also the key to the success or failure of the research and development of the hybrid electric vehicle.

When determining the control strategy of the hybrid powertrain, first of all, it is necessary to clearly put forward the goal to be achieved by the control strategy (that is, the control goal), and then select the appropriate control method based on the control goal and the analysis and comparison of various control methods.

The control objectives of the hybrid powertrain mainly include the goal of optimal fuel consumption and emissions of the vehicle and the goal of minimal battery power consumption. Taking the best fuel consumption and emissions of the whole vehicle as the control goal can give full play to the advantages of HEVs. The control strategy controls the operation of the vehicle and also takes measures to maintain the state of charge of the battery, so as to improve the cycle life of the battery, so as to ensure sufficient The driving range is also the development trend of hybrid vehicle products. The control goal of the hybrid powertrain is to adjust the power output according to the driver's intention, aiming at the best fuel economy performance and emission performance of the whole vehicle.

Hybrid powertrain control methods usually include logic threshold control, dynamic adaptive control, logic fuzzy control and neural network control. Among them, the logic threshold control method is fast and simple, has strong practicability, and is widely used, while the other three control methods require a large amount of data collection and calculation, especially to collect a large amount of engine operating data in real time to calculate the optimal engine performance. The fuel consumption point and the optimal emission point, and the real-time tracking of the value changes during operation make the software and hardware of the control system too complicated. In addition, the improvement effect of the last three control methods on the target depends on the accuracy of the engine dynamic model and the accuracy of real-time and rapid detection of operating data. The deviation of the accuracy may lead to a sharp deterioration of the target effect. Therefore, the hybrid powertrain control system should adopt the logic threshold control method at present.

When the parallel hybrid power system adopts the logic threshold control method, there are two specific control strategies, namely, the control strategy of limiting the engine working range and the control strategy of weighted adjusting the engine working range. Both of these strategies control the engine and battery to operate within a high-efficiency range and provide the required torque by setting thresholds. As a load regulating device, the motor participates in driving when the vehicle needs a large torque output, and absorbs the residual torque of the engine to generate electricity when the vehicle only needs a small torque output, and maintains the state of charge of the battery pack at a high level. within the efficiency range.

When adopting the logic threshold control method, the series hybrid system mainly adopts the control strategy of limiting the working range of the engine. By setting the threshold value, the working range of the engine and the battery is limited to the high-efficiency range, and the motor is provided independently or jointly. Electric power. As an electric power adjustment device, the battery outputs electric power when the vehicle is in a condition with high power demand such as acceleration or climbing; when the power requirement of the vehicle is not high, it can use the surplus power of the engine to charge to maintain the state of charge within a certain range .

For the hybrid hybrid system (the drive device adopts a planetary gear mechanism), the logic threshold control method is mainly adopted to limit the working range of the engine. According to the instantaneous state parameters of the power source (such as speed), battery parameters ( SOC) and vehicle parameters (such as vehicle speed) to set the threshold value to ensure that the power output of the power source meets the power demand of the vehicle, so as to realize the driver's intention.

On the basis of the research results of the control strategy, by studying the requirements of the whole vehicle for the control system, the scheme design of the control system is completed, mainly including the hardware design and software design of the control system.

1) Functional requirements of the hardware structure

The design of the hardware structure scheme is based on the requirements of the vehicle for the hybrid powertrain control system. The requirements of the vehicle for the control system mainly include the following aspects.

(1) The hybrid powertrain must output the driving or braking torque according to the driver's intention. When the driver depresses the accelerator or brake pedal, the hybrid powertrain outputs a certain driving torque or regenerative braking torque. The greater the pedal opening, the greater the torque output from the hybrid powertrain. Therefore, the control system needs to be able to receive the pedal opening signal and convert it into a torque output request for the hybrid powertrain.

(2) The power output of each power element in the hybrid powertrain must be controllable. The power element needs to perform corresponding power output or state transition according to the control command. Therefore, the control system should include the control unit of the power element to realize the functions of receiving the control command signal, adjusting the power output and state conversion of the power element.

(3) The control system of the hybrid powertrain must calculate the working state and power output requirements of each force element according to the pedal opening signal and the feedback signal of the power element, and output control commands to the control unit of the power element.

2) Structural design of control system software

Based on the hardware structure scheme of the control system, the functional requirements of the control software are put forward. The functional requirements of the control software are different for the hybrid systems of different modes.

(1) Functional requirements of parallel hybrid system control software

① Convert the pedal opening signal into the torque output request for the hybrid powertrain.

The control software needs to determine the relationship between the pedal opening and the torque output requirement, and also determines the distribution ratio of the regenerative braking torque to the mechanical braking torque and the distribution ratio of the front and rear wheel braking torque in the braking condition.

② Determine the working state of the engine.

The control software needs to decide whether the engine is running or stopped according to the requirements of the driving conditions and the efficiency of the engine in different working areas, with the goal of the engine working in the high-efficiency area.

③ Determine the torque output of the engine.

The control software needs to adjust the engine according to the requirements of the driving conditions and the working state of the engine, so that it runs in the high efficiency range, so as to determine the torque output of the engine.

④ Determine the torque output of the motor.

The control software needs to adjust the torque output of the motor according to the requirements of the driving conditions and the torque output of the engine to meet the torque output requirements of the vehicle, thereby determining the torque output of the motor.

(2) Functional requirements of control software for series hybrid power system

① Convert the pedal opening signal into the torque output request for the hybrid powertrain.

This is the same as the software functional requirements of a parallel hybrid system.

② Determine the electric power input and torque output of the motor.

Since the series hybrid electric vehicle uses the electric motor as the only power output device, it is necessary to determine the relationship between the torque output requirement of the hybrid powertrain and the torque output of the electric motor, and determine the corresponding electric power input according to the torque output requirement of the electric motor. .

③ Determine the working state of the engine-generator set.

According to the electric power input requirements of the motor and the efficiency of the engine in different working intervals, the engine generator set is determined to be in the running or shutdown state with the goal of the engine working in the high-efficiency interval.

④ Determine the torque output of the engine generator set.

According to the electric power input requirements of the electric motor and the working state of the engine-generator set, the engine is adjusted to operate in a high-efficiency range, thereby determining the torque output of the engine.

At present, the hybrid electric vehicles researched and developed in various countries in the world have different structural forms. According to the configuration and combination of their drive systems, they can be divided into three types of power combinations: series, parallel and hybrid.

(1) Tandem drive system

The energy flow in a series hybrid drive is shown in Figure 2. A series hybrid vehicle usually integrates an engine and a generator into one, the engine drives the generator to generate electricity, and the generated electrical energy is directly transmitted to the motor through the controller, and the motor generates torque to drive the vehicle. The battery actually plays the role of balancing the output power of the engine and the input power of the motor, that is, when the power generated by the generator is greater than the power required by the motor, the controller will use the surplus power of the generator to charge the battery and convert it to The electrical energy is stored; when the power output from the generator is lower than that required by the electric motor, the battery provides additional electrical energy to the electric motor. A series hybrid system uses a smaller engine to operate in the most efficient rev range, thereby maximizing fuel economy and reducing emissions.

Figure 2 Schematic diagram of energy flow in series hybrid drive mode

Since the engine of a series hybrid vehicle is not directly related to the driving conditions of the vehicle, the main goal of its control strategy is to make the engine work within the optimal efficiency range and emission range. Series hybrid vehicles have the following two basic control modes.

①Thermostat control mode.

When the state of charge (SC) of the battery drops to the set low threshold value, the engine starts and outputs a constant power at the minimum fuel consumption point or emission point. Part of the power is used to meet the driving requirements of the vehicle, and the other part of the power is The battery is charged; and when the SOC of the battery pack rises to the set high threshold value, the engine is turned off, and the battery pack provides energy for the electric motor to drive the wheels. In this mode, the battery pack must meet all the instantaneous power requirements, but the losses caused by excessive cycling of the battery pack may reduce the gain brought by the engine optimization, so this mode is more beneficial to the engine than to the battery. .

②Power tracking control mode.

This method mainly determines the on-off state and output power of the engine according to the SOC and load of the battery, so as to meet the power demand of the vehicle. When the engine power demand is less than the output power, adjust the engine output power to the minimum value: when the SOC is higher than the lower bound, and the total demand load of the car does not exceed the battery capacity but exceeds the maximum engine power, the engine output power is adjusted to the maximum value. The power of the engine follows the driving power of the wheels, which is similar to the operation of a conventional internal combustion engine car.

Comparing these two control modes, the engine in the thermostat control mode generally works near the optimal fuel consumption point, and the power-following engine generally works near the optimal economic working line. In comparison, the average working efficiency of the former engine is higher. However, the power-following control strategy has better comprehensive performance in terms of power and fuel economy. The above two control modes can be used in combination, and the purpose is to make full use of the high-efficiency area of ​​the engine and battery to achieve the highest overall efficiency.

(2) Parallel drive system

The structure of the parallel hybrid drive system is shown in Figure 3, and the vehicle can be driven by the engine and the motor together or independently. If the motor is only used as an auxiliary drive, its power is relatively small. Compared with the series structure, the engine in the parallel hybrid system can directly drive the vehicle through the mechanical transmission mechanism, and its energy utilization rate is relatively high, and the fuel economy is higher than that of the series drive system. The parallel drive system is suitable for stable driving conditions on inter-city highways and highways. Since the operating conditions of the engine in the parallel drive system are affected by the driving conditions of the vehicle, it is not suitable for the environment where the driving conditions of the vehicle change frequently and greatly. In addition, compared with the series structure, the parallel drive system requires a speed change device and a power coupling device, and the transmission mechanism is more complicated.

Figure 3 Structure of the parallel hybrid drive system

The control strategy of the parallel hybrid vehicle usually makes the engine and motor output corresponding torque according to certain rules according to the SOC of the battery, the position of the accelerator or brake pedal, the speed of the vehicle and the average power of the driving wheel, so as to meet the needs of the vehicle for driving. torque requirements.

(3) Hybrid drive system

The hybrid drive system is a combination of series and parallel. Part of the power of the engine passes through the mechanical transmission mechanism

It is sent to the drive axle, and the other part drives the generator to generate electricity. The electric energy generated by the generator is sent to the motor or battery, and the driving torque generated by the motor is transmitted to the drive axle through the power coupling device. The control strategy of the hybrid drive system is: when the car is running at low speed, the drive system mainly works in series; when the car is running at high speed and stably, it mainly works in parallel. In the hybrid drive system, The work of the engine is not affected by the driving conditions of the car, and can work at the highest efficiency state or automatically shut down, so that the car can achieve low emissions and ultra-low fuel consumption at any time, and achieve good environmental protection and energy saving effects. This method can better meet the performance requirements of the car, but the control technology is complex, and the structural design and manufacturing requirements are high.

According to the different energy supply methods, the basic working modes of the parallel hybrid system can be divided into pure electric drive mode, pure engine drive mode, driving charging mode, hybrid drive mode, deceleration/braking energy feedback mode and idle/stop mode, etc. types. The operating modes corresponding to different stages in the driving cycle are shown in Figure 4.

Figure 4 Working modes corresponding to different stages of the driving cycle

(1) Pure electric drive mode.

When the state of charge (SOC) of the power battery is higher than the lower limit and the vehicle is in a light-load starting condition, the clutch between the engine and the transmission system is disengaged, the power of the engine is cut off and the engine is stopped, and the power battery provides the required starting conditions for the vehicle to start. energy and the electric motor drives the vehicle to run. If the engine is used as the power source to drive the car in this working condition (that is, when it is in the starting condition of a traditional internal combustion engine vehicle), due to the poor combustion of the engine at low speed, the thermal efficiency is low, which will cause the engine Emissions performance at this stage is poor and fuel consumption is high. However, when the power of the power battery is lower than the lower limit (that is, when SOC

(2) Pure engine drive mode.

Under normal driving conditions, the power required by the vehicle to overcome the road resistance is small, and the engine is generally powered by the engine.

(3) Driving charging mode.

When the power of the power battery is relatively low, in addition to providing the engine to overcome the road resistance

In addition to the required power, additional power is also provided to drive the generator to generate electricity, which converts part of the mechanical energy into electrical energy and stores it in the power battery for use in other working conditions.

(4) Hybrid drive mode.

Under heavy load conditions such as accelerating or climbing, when the power required by the vehicle exceeds the economical fuel consumption of the engine, the power battery outputs energy to drive the electric motor to provide auxiliary power to the vehicle. When the SOC of the power battery is low, the electric motor no longer works, and the engine runs at full power to provide the maximum power output. At this time, the vehicle is in a pure engine working mode.

(5) Deceleration/braking energy feedback mode.

The vehicle usually has two working modes under the deceleration/braking condition, one is to slowly reduce the vehicle speed and recover most of the deceleration braking energy only through the anti-drag effect of the motor; the other mode is to use more urgent braking. When there is a demand for power, the speed of the vehicle is rapidly reduced by the combined action of the motor anti-drag and the mechanical braking system. Part of the braking energy is recovered by the motor and stored in the battery pack, and the other part is converted into heat energy through the friction of the mechanical braking system.

(6) Idle/stop mode.

There is no energy flow in the hybrid drive system in idle/stop mode, and the engine and electric motor are normally shut down. However, when the SOC of the power battery is relatively low, the engine needs to be started and run in the economic working range to charge the power battery for use when needed.

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