Towards Standardization of DC Charging for Light E-Vehicles

With inputs from Bharat Charge Alliance

90% of EV sales in India comprise Light Electric Vehicles (LEVs) – mainly 2Ws, 3Ws, and small 4Ws. LEV sales are expected to make up 80% of all EV sales in 2030. The two-wheeler and three-wheeler industry is unorganized in terms of charging interoperability and rapid charging. There is no standardized charging communication protocol, and no common charging connectors have been adopted across the 2W and 3W industries.

DC Charging for LEVs | Current Scenario

Light Vehicle OEMs do not prefer to provide an onboard charger due to its packaging and thermal heat dissipation constraints. Low-power rectifiers can still be used as onboard chargers, but they increase the charging time. Secure electrical isolation/separation and leakage detection are needed when AC input is supplied to the vehicle. These are a few reasons why OEMs do not prefer onboard chargers. Instead, they prefer to offer offboard DC portable charger (less than 1 kW) for ease of charging, less complexity on the vehicle side and better customer experience and flexibility. The portable charger converts the AC input from mains to a DC input at the EV inlet.

In most cases, the charging pins on the grid side are designed to be compatible with normal domestic/industrial plugs (5A/15A), while the connector on the vehicle side is usually of a proprietary design.

Most 2W and 3W vehicle manufacturers have proprietary charging hardware, connectors and related communication protocols. The combination of vehicle inlet and charging communication protocol is a major disadvantage for EV users and CPOs as it limits the ability to use fast charging. For example, a public fast-charging DC network designed for one OEM may not be accessible to EV users of other OEMs due to connector and communication protocol incompatibility. This also limits the ability of the CPOs to provide widespread access to fast charging as they will have to set up chargers with multiple combinations.

For interoperability between different 2W/3W and charging equipment, the 4 key elements of the charging infrastructure need to be common. These are:

• Vehicle connector

• Charging communication protocol between EV and EVSE

• Communication between EVSE and Charger Management System (CMS)

• Communication between one CMS and another CMS for payment mechanism

Vehicle Connector and Charging Communication Protocol

The majority of the current LEVs are on 48V – 96V systems and are expected to remain so for a decade. In 2Ws, the maximum battery pack size is generally 5kWh (100Ah), considering its form factor and space availability, whereas in 3Ws, it is up to 11kWh (210Ah). It is anticipated that, with the existing battery chemistries, the battery capacity for LEVs may not go beyond 15kWh in the short-to-medium term because of space and pricing constraints.

Bharat Charge Alliance (BCA) recommends the IS17017-2-6 standard published by BIS, which specifies the vehicle inlet and charger connector for the LEV requirement. This connector is recommended for up to 120VDC and 100A DC continuous current applications. The advantage of this connector is that the locking feature is on the charger connector side and not on the vehicle inlet side. This enables vehicle manufacturers to have minimum investment and no architectural complexity to adopt this connector. “This IS17017-2-6 connector (also known as Type-6 connector), coupled with IS-17017-25, can establish interoperable charging infrastructure for Light EVs in India”, said Kapil Shelke from BCA. The vehicle inlet is already localized, and several vendors are manufacturing it in India, he added.

The figure below showcases a brief comparison of the existing LEV connectors adopted by the vehicle manufacturers and the proposed standard connector.

Features of IS-17017-2-6 and IS17017-25 standard

• EV side – Low cost (no latching), simple electronics on VCU & BMS; suitable for 20V to 120V DC, 15A to 125; minimum change in the vehicle.

• EVSE side – Small form factor for public infrastructure. Off-the-shelf power electronics modules.

• In both instances, whether an AC supply is used for the portable charger or a fixed DC  supply is used for fast charging, the same DC Charging Interface is used regardless of the type and capacity of the power supply.

• CHAdeMO Association has already developed the specifications (e-PTW), which define a DC charging method covering voltage up to 120VDC and 100ADC current. OEMs can adopt the same specifications.

• The proposed connectors can support a spectrum of vehicles like e-bikes, Moped, scooters, motorcycles, delivery scooters, tricycles, e-freight, e-rickshaw, e-ATV, e-buggy, e-cart, e-auto, electric forklifts, golf carts, etc

Several EV companies, such as OLA, TORK, Ultravoilette, Simple Energy, and Log9, have started using the Type 6 connector. This connector, which can support up to 125A continuous charging current, is also gaining popularity among e3W (L5) OEMs like Altigreen, ETO Motors, and Surja Automotive, whose vehicles have larger battery packs, as per a BCA statement.

ARAI, India’s leading testing and certification agency, has built the testing capability for the IS 17017-2-6 connector and the IS 17017-25 protocol.

As of today, the Indian 2W industry is quite spread out in terms of EV charging connectors. Though there are 10+ kinds of connectors that different OEMs currently use, Type 6 and Ather Connector are the two main efforts towards standardization of DC charging among e-2Ws.

Ather has pushed for a combined port solution [IS-17017 Part 2 / Sec 7], which includes both AC and DC charging capabilities. So far, Ather Energy and Hero MotoCorp have adopted the standard.

There have been reports about an e-motorcycle company opting for the CCS2 standard. However, it must be noted that CCS2 is not suited for mass market LEV techincal specifications and doesn’t have financial viability for mass-market EVs.

Type 6 vs Type 7 Connector

When asked to compare Type 6 and Type 7 connectors, Kapil highlighted the ease of integration and simplicity in transition as the main factors that favour Type 6.

With Type 6, existing vehicles that use separate ports for AC and DC charging can easily transition. The switch involves replacing the existing connector (e.g., SB 75) with a Type 6 connector and making minor adjustments to the hardware and software, such as adding a microcontroller to monitor charging. In comparison, Type 7 may require more significant changes to vehicle architecture, protocols, and wiring harnesses. Moreover, the Type 6 connector works in conjunction with IS 17017-25 standards, whereas the electrical separation and communication standard for the Type 7 connector is not yet specified.

Communication between EVSE and CMS

The CMS is typically a networked software that helps to manage the charging business by allowing CPOs to track charger utilization, remotely start/stop operation, authenticate users, and collect payments for chargers within its network. In some cases, the CMS could also be independent and site-specific without any communication capability with a network. Open Charge Point Protocol (OCPP) is the dominant communication protocol that defines the standard communication between the EVSE and the CMS.

Communication between one CMS and another CMS

The fourth key element in interoperability is the payment mechanism. There has to be a decentralized open protocol that enables any CPO to list their chargers and any EV user to charge the vehicle on any charger. BCA recommends UEI (Unified Energy Interface), powered by the Beckn protocol, a transaction protocol that allows discovery, booking, start/stop and paying for a charging session between a user and a charge point.

About BCA – The BCA is an open platform for collaboration to create a safer and interoperable ecosystem for the LEV industry. Cross-industry stakeholders like EV OEMs, charger and charging station makers, component manufacturers, energy providers, charge point operators, and many others work together to form interoperable charging infrastructure.

Special thanks to Kapil Shelke (Founder, Tork Motors) and Anirudh Amin (Founder, CPO Assist) for their time and inputs.

Also Read: What’s next for Light EV Charging Standards in India?

This article was first published in EVreporter April 2024 magazine.