A quick rundown on EV chargers
Rahul George, Manager, Strategy and Business Planning
Read about the different modes of charging when it comes to recharging your electric vehicle be it within the vehicle or outside of it.




Overview



When you hear the term ‘Public EV Charging Infrastructure’, what’s the first image that comes to your mind? If it’s a row of heavy-duty machinery that can charge a car in minutes, you wouldn’t be alone. High power or Ultra-fast charging that can replenish an EV in the time it takes to have a coffee is the charging solution that has captured the imagination of EV enthusiasts world-wide.

This type of rapid charging however is just a small portion of the entire universe of charging. In this article we’ll take a look at the different types of charging or rather the various modes in which the energy within EV’s can be replenished.

A good way to understand potentially all the ways that could be present are to break down the universe in a way that is mutually exclusive and collectively exhaustive and to then look at available options within them.



Now let’s take a quick look at what each of these mean and their current spread of application.

Charging the battery within the car



As the title suggests, here the battery remains within the EV itself and the manner in which the energy is delivered from the Grid (Source of power) to the Battery (Store of energy) differs.

Normal Charging



This is the easiest to relate to and is akin to how majority of the appliances that we use at home operate. We connect the EV to a normal socket in the house (Typically a 15A socket, which is the plug type used for an Air Conditioner) via a charging cable provided by the EV OEM itself. The EV then starts charging. For the EV customer its as simple as that. Let us however dig a bit deeper to see what’s happening on the inside.



The grid gives us what is known as AC (Alternating Current). AC is what makes it possible for the utility provider to transmit power from the source of generation to across the state with minimal losses. However, EV batteries store the energy in the form of chemical energy that can be given or extracted as DC (Direct Current). Therefore, a conversion from AC to DC is required prior to the charging of the battery in normal charging. For typical 4W’s in the market like e2o, eVerito, Tigor EV etc. the conversion happens within the vehicle via an ‘On board charger’. For certain e 2WL and 3WL, the conversion happens outside the vehicle through an ‘Off board charger’.

For lighter EVs, normal 15 A sockets at home, provide a reasonable speed for overnight charging. But for higher capacity EVs and for public charging, an additional layer of electronics is usually provided for safer, intelligent and a more acceptable rates of charging.

Normal AC charging accounts for almost 90% – 95% of all charging across the world as it is the dominant mode at home, office and quite a large share of public charging. Its interoperability, low cost of hardware and low installation cost allows it to go widespread.

Fast(er) charging



Recall that batteries store chemical energy accessible in the form of DC. Fast charging is based on the principle of supplying high power DC to the battery directly bypassing the AC-DC conversion that happens in the vehicle. The conversion to high power DC happens in the charger hardware itself.

The charging time is a factor of the capacity of the DC charger and the battery capacity of the vehicle. In a very simplistic illustration, a DC charger of 15 kW capacity can charge a vehicle with 15 kWh battery capacity in about an hour.

As EVs have evolved with higher battery capacities and the ability to accept higher rates of charging, DC fast chargers have also kept pace. There are now DC fast chargers available with capacities of up to 350 kW which can potentially offer charging times of less than 30 min to some EVs. But as DC fast chargers have much more sophisticated hardware, their costs are also higher. This leads them to be utilized in very specific use cases where they add value like Highway charging networks or commercial fleet charging networks. On a whole, DC fast chargers make up about 5 – 10% of all charging done globally.

We would take a deeper look at DC fast charging, standards and India suitability in the later articles.

Wireless & Overhead charging

These two modes of charging are clubbed together as they represent the smaller scale, forward-looking experiments in charging happening right now in parts. Wireless charging refers to the EV parking over a designated charging pad and automatically starting to charge (Much like in the way certain premium mobiles now come with wireless charging functionality and pad). This could lead to some very interesting use cases coming up in the future once the technology becomes robust and commercially viable.

Overhead charging or Pantograph charging is at a slightly more advanced stage and refers usually to high power opportunity charging that can be provided to ebuses along the route via fixed ‘Pantographs’ at the stops / stations. They have the ability to pump in a significant amount of energy in the 5 – 10 min that a bus would stop at the station. However, the battery chemistry in the EV also needs to be suitable to be able to take such a high rate of charging. Basis the commercial viability, this also has the potential to be an interesting charging solution for specific use cases.

Charging the battery outside the car





Battery Swapping



The philosophy of Battery Swapping is to provide the customer the same convenience that they would have been used to at a petrol pump. Namely that of being in and out in a matter of minutes with a full tank. The idea was first conceptualized in the western market for 4WL, however did not take off due to commercial viability constraints. It is now being piloted for smaller segment vehicles like e-2WL and e-3WL in emerging markets like SE Asia and India. While it offers good convenience, the long-term viability remains to be established along with greater clarity on regulations around ownership of the vehicle and the batteries being separate.

Conclusion



Just like EVs, EV charging is also an evolving space with new technologies and techniques emerging quite rapidly. There are few interesting experiments in charging happening in other areas like Metal Air batteries and Fuel Cell Vehicles. However, as they do not deal with Li-Ion batteries and are at an extremely nascent stage, they have not been included in the scope of this article. Though simplified to a good extent, the technologies mentioned above, and their variations and evolutions seem to be the mainstay of EV charging in the near future.
Download the app now

The Mahindra Electric customer app is currently in Beta and hence some car care app features are under development. For any help on the car app or suggestions, please contact our Customer care team through the mobile app.