Vehicle to Load (V2L) in EVs: What is it and How Does It Work?

Vehicle to Load (V2L) in EVs: What is it and How Does It Work?

Read Bidirectional OBCs in EVs to understand this article better.

EVs have revolutionized transportation with their eco-friendly and efficient technology. Among the many advancements in EV technology, V2L functionality stands out as a feature that significantly enhances the utility of EVs. V2L allows EV owners to use their vehicles as portable power sources, enabling them to power external devices, appliances, or even homes. This article delves into the details of V2L, its components, applications, and operational mechanisms.

Abbreviations:
EV = Electric Vehicle
EVI = Electric Vehicle Charging Inlet
EVCC = Electric Vehicle Communication Controller
HVB = High Voltage Battery
HMI = Human Machine Interface (Display or Mobile)
OBC = On-Board Charger
SOC = State of Charge
V2L = Vehicle to Load

What is V2L?

V2L is a bidirectional power feature that enables an EV’s battery to supply power to external AC loads, such as tools, appliances, or other devices, without requiring integration with the power grid. It transforms an EV into a portable power station, making it invaluable in off-grid scenarios or during power outages.

Where is V2L Useful?

V2L proves to be a versatile and practical feature in several scenarios. Few of them are mentioned below:

  • Camping and Outdoor Activities: Powering portable refrigerators, lights, and other appliances at campsites.
  • Emergency Power: Providing electricity for essential devices, such as medical equipment, during power outages.
  • Home Appliances: Powering household devices like refrigerators, washing machines or microwaves during blackouts.
  • Construction Sites: Supplying power to tools and other equipment in remote areas.

What is the Power Level of V2L?

The power levels in V2L are determined by the capabilities of the bidirectional OBC. Typically, most systems can deliver power between 1.5 kW and 3.6 kW, which is adequate for powering small appliances and tools. However, V2L can also be designed to support higher power levels.

Key Components of V2L

To enable V2L functionality, additional components are required beyond the standard EV hardware. These include:

1. V2L Adapter

The V2L adapter is essential for converting the EV’s inlet into a standard power socket. Key features include:

  • Physical Conversion: Converts the EV inlet to a regular power socket.
  • Proximity Resistance (RV2L): Equipped with a unique proximity resistance not part of existing standards, allowing the EV to recognize it as a V2L adapter. (Note: It is possible to use other methods to detect a V2L adapter, but this is the simplest approach and is commonly used by most EVs.)
    Ex: RV2L = 50 Ω (which is not part of the IEC 61851-1 as shown below)
Proximity Resistance (As per IEC 61851-1)Current Carrying Capacity of the Charging Cable
1500Ω13A
680Ω20A
220Ω32A
100Ω63A
  • Power On/Off Switch: Allows users to On/Off the power.
  • Status Light: Indicates the power status, lighting up when power is on and switching off when power is off.
EV with V2L adapter

Note: The ‘Power On/Off Switch’ is a normally closed switch, designed to detect the state of RV2L. When the switch is in the “off” position, the internal switch remains closed. Conversely, when the Power On/Off Switch is turned “on,” the internal switch opens.

Different V2L adapters

2. Bidirectional OBC

The bidirectional OBC is a critical component that manages the conversion of battery power into usable AC power. Its key functionalities include:

  • Voltage and Frequency Regulation: Provides constant voltage and frequency based on regional standards.
  • Isolation Monitoring: Ensures safety by monitoring isolation between phase, neutral, and protective earth (PE). Traditional residual current devices (RCDs) are challenging to implement in this setup, making isolation monitoring essential.
  • Load Management: Handles sudden load changes, such as switching appliances on or off, without system failures.
  • Overload Protection: Limits power delivery and shuts off if overload conditions are detected.

Read Bidirectional OBCs in EVs for more details.

How Does V2L Work?

V2L functionality involves a sequence of operations to ensure safe and efficient power delivery. The process can be divided into two main stages: powering on and powering off.

Powering On Sequence

  1. Set SOC Limit: The user sets a SOC limit on HMI (display in car) at which the V2L discharge should stop.
  2. Connect Adapter: The user connects the V2L adapter to the EV.
  3. Adapter Recognition: The EVCC measures the proximity resistance to detect the V2L adapter and locks it in place.
  4. Power Request: The user switches on the adapter, triggering a change in proximity resistance that the EVCC detects as a power-on command.
  5. System Checks: Upon EVCC’s request, the HVB performs checks for isolation resistance, temperature, and faults. If all conditions are safe, it closes the high-voltage contactors.
  6. Voltage Delivery: The EVCC instructs the bidirectional OBC to provide constant voltage and frequency. Once power is available, the status light on the V2L adapter lights up.

Powering Off Sequence

  1. Power-Off Request: The user switches off the adapter, causing a change in proximity resistance that the EVCC detects as a power-off command.
  2. Disable Voltage: The EVCC instructs the bidirectional OBC to stop voltage delivery.
  3. Delay and HVB Shutoff: After voltage is turned off, the EVCC may wait briefly to ensure no additional power requests are made. It then requests the HVB to turn off the high-voltage contactors.

This sequence provides a basic understanding of the steps involved in the V2L process, though the exact steps may vary based on design choices.

V2L in use

Automatic Stop at SOC Limit

If the battery SOC reaches the user-defined limit, V2L automatically stops to preserve the vehicle’s primary function: driving.

Status LED on Charging Inlet

Throughout the process, the status LED on the charging inlet can indicate the ongoing status, keeping the user informed that the EV is processing operations internally. This prevents user confusion or panic during transitions.

In conclusion, V2L technology significantly enhances the practicality and versatility of electric vehicles, transforming them into portable power stations. With applications ranging from camping to emergency preparedness, V2L showcases the evolving potential of EVs beyond transportation. As this technology becomes more widespread, it will continue to redefine how we utilize and interact with energy in our daily lives.

Amar Reddy Avatar
Amar Reddy, a seasoned professional in EV Charging with more than a decade of expertise in the Electric Vehicles domain. With a Master’s degree in Electrical Engineering, he is eager to share valuable insights into EV charging, catering to enthusiasts and fostering a deeper understanding of the field.

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