The Ostara Guide to EV Charging: Safe Charging Stations
Authors: Priyamvad Ranade & Vasudha Madhavan
In recent weeks, India has witnessed a spurt in EV fire incidents, which have even proved fatal! While the most common explanation given to these fires is the rising summer temperatures in India, nothing could be further from the truth. In this edition of the Ostara Newsletter, we attempt to demystify the causes of battery fires and emphasize the need for safe charging practices, as India moves towards greater EV adoption.
Electric Mobility is fast gaining momentum in India. In 2021, 3,29,190 were sold in India, representing a 168% increase over 2020 sales of 1,22,607 units.
Source: Vaahan Dashboard
With a combined market share of over 90%, 2-wheelers as well as L3 and L5 category 3-wheelers are the most popular electric vehicles in India.
As this momentum accelerates, we are witnessing a fundamental shift in the Mobility-Energy handshake. As ‘charging your vehicle’, rather than re-fueling it, becomes more common, we need to understand a few concepts and frameworks that are critical to safety in this transition.
Who are the key stakeholders in the Indian EV Charging Value Chain?
An overview of Chargers and Charging Protocols in India
EV charging involves supply of direct current (DC) to the battery pack. As electricity distribution systems supply alternating current (AC), a converter is required to provide DC power to the battery. Most chargers can be classified into one of two types:
AC chargers, which provide alternating current (AC) power to a vehicle’s on-board charger from an electrical utility supply
DC chargers, which provide direct current (DC) power to a vehicle’s battery system, bypassing the on-board charger.
AC & DC charging are classified into four charging modes
Modes 1 and 2 are applicable for charging an EV using a standard socket outlet, utilising a cable and plug. The portable cable used in Mode 2 has an inbuilt protection and control capability and is typically used for home charging.
Modes 3 and 4 which use a separate charger device to supply power to the EV, have improved control systems and are used for commercial or public charging.
Source: NITI AAYOG
Source: Ministry of Power
Global Charging Standards
The EV charging connector or plug type standard varies across geographies and models. While there is contention around universal plug technology, there is critical mass from global automakers supporting the Combined Charging System (CCS) in North America and Europe, while Japan and its automakers use CHAdeMO, and China, which has the world’s largest electric vehicle market, uses GB/T. Tesla have developed a proprietary dual-connector charge-port design.
Currently, charging networks are connected using a data cable to form a local network and often use proprietary charging management system (CMS).
The Open Charge Point Protocol (OCPP) is an open-source communication protocol for networked EV chargers. The vision of OCPP is to make any EV charger work with any CMS.
Why do Batteries catch fire?
The arrival of electric mobility has created a need for ubiquitous charging facilities. Each electric charger creates a risk of short circuits and fire, even more so in the case of fast & rapid-charging, where the current-voltage is high and the batteries generate a lot of heat. In fact, it’s the battery that can be the source of a potential fire.
99% of battery fires are due to short circuits leading to uncontrolled current which results in the increase in a cell's temperature by a few hundred degrees Celsius, leading to thermal runaway.
Short circuits happen for three reasons:
1. Poor cell quality
2. Poor design of the battery (the way cells are connected & packaged)
3. Poor BMS (management of cells via sensing & software intelligence)
We recommend this excellent blog on this topic by the good folks over at Exponent Energy.
Safe Charging Stations - A Ready Reckoner
All Charging Stations
Every socket-outlet of supply is at least 800 mm above the finished ground level, when installing EV charging points.
Portable socket-outlets are not permitted to be used for electric vehicle charging.
Lightning protection system to be in place as per Indian Standards Code IS/ IEC 62305.
An adaptor shall not be used to connect a vehicle connector to a vehicle inlet.
All apparatus of charging stations shall have the insulation resistance value as stipulated in the relevant IEC 61851-1.
To guarantee the electrical safety of the charging circuit, it is set up as an ungrounded / floating DC power supply system with insulation monitoring
The IMI in the vehicle needs to be disabled during the charging process to avoid interference.
In the case of Earth Protection,
Each EV charging point to be supplied individually by a dedicated final sub-circuit protected by an overcurrent protective device (OPD) complying with applicable standards and the OPD shall be part of a switchboard.
All EV charging stations shall be supplied from a sub-circuit protected by a voltage-independent residual current device
An earth continuity monitoring system to be in place which disconnects the supply if the earthing connection to the EV becomes ineffective.
For Fire Prevention,
Enclosure of charging stations to be made of fire retardant material with self-extinguishing property and free from Halogen.
Fire-fighting system for charging stations to be provided in accordance to the guidelines prescribed.
Power supply cables used in charging stations or charging points shall conform to IEC 62893-1 and its relevant parts.
A Quick Explainer:
IS standards are specialized standards for electronics and related technologies pertaining to India. BIS is the National Standard Body of India established under the BIS Act 2016 for the harmonious development of the activities of standardization, marking and quality certification of goods and for matters connected therewith or incidental thereto.
The International Electrotechnical Commission (IEC) is an international standards organization that prepares and publishes international standards for all electrical, electronic and related technologies – collectively known as "electrotechnology". IEC standards cover a vast range of technologies from power generation, transmission and distribution to home appliances and office equipment, as well as many others.
IEC 61851 is an international standard for electric vehicle conductive charging systems,1 is one of the International Electrotechnical Commission's group of standards for electric road vehicles and electric industrial trucks
IEC 62893-1 talks about Charging cables for electric vehicles for rated voltages up to and including 0,6/1 KV – Part 1: General requirements
IEC 62305 - informs the standards for lightning protection around the world. It is a design standard that comprises four documents that provide the lightning protection designers with the rules and regulations they require to design an LPS.
IEC 60947-1 applies to low-voltage switchgear and controlgear which is intended to be connected to circuits, the rated voltage of which does not exceed 1000 V AC or 1500 V DC. It states the general rules and common safety requirements for low-voltage switchgear and controlgear, including environmental aspects, characteristics, etc.
IEC 60269 is a set of technical standards for low-voltage power fuses.The standard is in four volumes, which describe general requirements, fuses for industrial and commercial applications, fuses for residential applications, and fuses to protect semiconductor devices.
Ostara in the news!
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