Portable EV Chargers: Working, Types, Components, Benefits and Safety
The use of electric vehicles (EVs) is growing steadily, and charging infrastructure is expanding to include home, workplace, public and fast-charging facilities. However, there may be occasions when the preferred or designated charging station is unavailable. A portable EV charger can solve this issue.
A portable EV charger allows an electric vehicle to be charged from a suitable electrical supply without the need to install a permanent charging station. It can be transported and connected to a suitable power supply wherever it is needed.
Portable EV chargers are useful for normal charging, travel, temporary charging needs, as a backup option, and other applications. However, understanding its working principle, electrical requirements, charging limitations and safety features is essential before using such equipment.
What is a Portable EV Charger?
A portable EV charger is a transportable device used to provide electrical power to an electric vehicle for charging its battery. Unlike a fixed or permanently installed wall-mounted charger, a portable charger can be taken to the desired location and connected when required.
Technically speaking, many portable AC charging products are a form of Electric Vehicle Supply Equipment (EVSE). The EVSE provides the interface between the electrical supply and the vehicle and performs essential control and protection functions.
Many portable AC charging products utilize an In-Cable Control and Protection Device (IC-CPD) as part of the charging cable. The IC-CPD can provide functions such as charging control, fault detection. and protection. IEC 62752 specifies requirements for IC-CPDs used for Mode 2 charging.
The charging speed of the portable charger itself therefore depends on not just the charger rating, but the available electrical supply and the vehicle's charging capability.
How Does a Portable EV Charger Work?
The working principle of a portable EV charger depends on whether the system provides AC or DC power.
The basic energy path in a typical portable AC charging arrangement would look like the following:
AC Power Supply → Portable EVSE → Vehicle Charging System → Battery
During AC charging, the vehicle's onboard charger is used to convert the incoming AC electricity to the DC electricity which is required by the battery. The onboard charger also controls the charging process according to the vehicle's needs.
The portable EVSE performs control and protection functions between the power supply and the vehicle. It can detect charging conditions and depending on the design, it can detect electrical faults or abnormal operating conditions.
In a DC charging system, the conversion from AC to regulated DC is performed outside the vehicle's onboard AC charger. The resulting DC power is then supplied to the vehicle's battery system via the charging equipment.
Portable AC chargers are generally much simpler than mobile DC charging systems as they do not involve the power conversion needed for DC charging.
[Also Read: Electric Braking]
Main Components of a Portable EV Charger
The construction of a portable EV charger varies depending on its design and power rating, but the following components are generally present in portable charging equipment:
- Input Plug
The input plug connects the portable charger to an electrical power source. The voltage and current rating of this connection is critical and must be compatible with the electrical outlet and installation being used.
- Charging Cable
The charging cable provides the electrical energy link between the power source and the vehicle. The cable must be suitable for the working voltage and current.
Cable construction and insulation is significant as EV charging involves high current for extended periods.
- Control and Protection Unit
Many portable EV chargers have a control and protection unit which can handle communication between the charger and vehicle and provide the necessary protective functions.
Some control and protection units can monitor current, temperature, leakage or other abnormal conditions and disconnect the power when a fault is detected.
- Vehicle Connector
The vehicle connector provides the link between the portable EV charging equipment and the vehicle.
The vehicle connector must be compatible with the vehicle being charged. Different regions and vehicle manufacturers use different EV charging standards, so compatibility should always be checked.
- Indicators and Control Circuitry
Many portable chargers provide indicators which show the operating condition of the equipment. This can include indicators for power availability, charging status, selected current or fault conditions.
[Also Read: BLDC Motors]
Types of Portable EV Chargers
Portable EV chargers can be classified depending on their charging method and electrical characteristics.
- Portable AC Chargers
Portable AC chargers are often used for home, travel, workplace and other charging where a suitable AC power outlet is available.
The charger provides AC power to the vehicle, with the vehicle's onboard charger performing the conversion from AC to DC. The charging power available from a portable AC charger depends on the electrical supply and the charger rating. Low-power portable chargers can be connected to a suitable conventional outlet but higher-power portable units may require a dedicated and correctly rated circuit.
- Portable DC Chargers
Portable DC charging equipment provides controlled DC power to the vehicle rather than relying on the vehicle's onboard AC charger to perform the primary power conversion.
Portable DC systems generally require more sophisticated power electronics, thermal management, control systems, control systems and protection equipment than portable AC systems, as DC charging can operate much higher power levels.
They can be useful for specialist applications where mobile high-power charging is required. However, the size, weight, cost, and electrical requirements can be significantly greater than portable AC chargers.
Charging Speed and Power Rating
One of the most important specifications of a portable EV charger is its power rating.
For a single-phase AC system, electrical power can be approximately represented by P = V x I or in formula terms, P = V × I, where P = electrical power in watts, V = voltage in volts, and I = current in amperes.
For AC systems, actual power can also depend on factors such as power factor and efficiency.
For example, increasing the charging current can increase the available power when the electrical supply and vehicle permit it. However, the maximum charging current should never exceed the rating of the charger, outlet, wiring, or protective equipment.
The vehicle may also limit the available power. Therefore, installing or using a higher-rated charger does not necessarily mean that the vehicle will charge at that maximum rate.
Battery state of charge and temperature can also affect charging speed. Charging power can change during the charging cycle as the vehicle battery approaches a higher state of charge.
Benefits of Portable EV Chargers
Portable EV chargers can provide a number of benefits for electric vehicle users.
- Flexibility
The main benefit of a portable charger is its portability. A charger can simply be carried in the vehicle and used at different suitable locations.
- Backup Charging
A portable charger can also provide a backup option when the preferred charging station is unavailable or inaccessible.
- Useful for Travel
A portable charger can be useful for long-distance travel, temporary accommodation, campsites, workplace and other EV charging needs at a suitable location.
- No Permanent Installation
A portable charging unit generally does not need to be permanently installed at a specific location. This can be useful to users who need occasional charging at different places.
- Adjustable Charging Options
Some portable chargers allow the user to select different current levels. This lets the charging load match the available electrical supply, provided the selected value is within the capabilities of the installation and charger.
Limitations of Portable EV Chargers
Despite its flexibility, the portable EV charger has some limitations. The first limitation is the charging speed. A portable charger connected to a lower-power electrical outlet can take considerably longer to charge an EV battery than a higher-power charging station.
Another limitation is the electrical infrastructure. A portable charger cannot compensate for an undersized electrical circuit. The outlet, wiring, protective devices and grounding system must all be suitable for the charging load.
Being portable can come at the expense of size and power. Higher-power charging equipment generally requires larger cable size, more robust components and better thermal management.
Environmental conditions are also a consideration. A portable charger designed for outdoor use must have appropriate protection against moisture, dust, temperature and other environmental factors.
Safety Features and Precautions
Safety is one of the most important aspects of EV charging, as charging equipment may carry significant electrical current for a relatively long period of time.
Portable EV charging equipment can incorporate a number of safety and protection functions depending on its design. These can include overcurrent protection, residual-current or leakage protection, over-temperature protection, overvoltage and undervoltage protection, protective earthing or grounding, fault detection, control-pilot communication and automatic charging interruption during certain fault conditions.
The exact protection system depends on the equipment and applicable standards. Users should always inspect the charging cable, plug and connectors before use. Damaged or overheated equipment should not be used.
The electrical outlet must be suitable for the charger's rated current. Loose or damaged outlets can cause excessive resistance and heat during prolonged charging.
Extension cords, adapters or plug converters should only be used if they are specifically permitted by the charger manufacturer and correctly rated for the electrical load. An unsuitable extension cord can overheat and cause a serious electrical hazard.
Portable chargers should also be used according to their environmental rating. Equipment not suited for wet conditions should not be exposed to rain or standing water.
Portable EV Charger vs Fixed Charger
Portable and fixed EV chargers serve similar basic purpose, but their applications are different.
A portable charger offers greater mobility and can be useful when charging is required at different locations. A fixed charger is permanently installed and can be connected to a dedicated electrical circuit designed specifically for EV charging.
A fixed charging system may provide higher, more consistent charging power when supported by an appropriate electrical installation. A portable charger is generally more useful where flexibility and mobility are the primary requirements.
The choice between the two options depends on the vehicle, available electrical infrastructure, charging frequency, required speed and intended application.
How to Choose a Portable EV Charger
Several factors should be considered prior to selecting a portable EV charger.
First, check compatibility with the vehicle and its charging system. The charger's input requirements should also be compatible with the available electrical supply.
The charger's current and power ratings are equally important. The electrical outlet and circuit must be able to safely deliver the required load.
Other factors include cable length, portability, protection features, environmental rating, operating temperature range, indicators or displays, and compliance with applicable safety standards.
A charger with adjustable current settings can provide added flexibility, but the selected current should always be within the limits of the electrical installation.
Applications of Portable EV Chargers
Portable EV chargers can be used in many situations where flexible EV charging is required.
The common applications of portable EV chargers include home, workplace, road trips and travel, temporary charging, backup, campsites, service and fleet applications and locations without permanent EV charging equipment.
The portability of the charger allows EV owners to carry the charging equipment with them rather than relying on fixed charging infrastructure.
Conclusion
Portable EV chargers provide a flexible solution for charging electric vehicles at different locations where suitable electrical power is available. It can be particularly useful for travel, backup charging, temporary applications and users who need greater mobility.
A portable EV charger typically combines electrical power delivery with control and protection functions. Its charging performance depends not only on the charger's rating but also on the electrical supply and the vehicle's charging capability.
When choosing and using a portable EV charger, compatibility, power rating, electrical installation, protection features, environmental conditions and manufacturer instructions should all be considered.
As electric vehicle adoption continues to grow, portable charging equipment can complement fixed home and public charging infrastructure by providing an additional and flexible method of supplying energy to electric vehicles.