How does the charging system work on an electric car?

Battery (all-electric auxiliary): In an electric drive vehicle, the auxiliary battery provides electricity to power vehicle accessories.

Charge port: The charge port allows the vehicle to connect to an external power supply in order to charge the traction battery pack.

DC/DC converter: This device converts higher-voltage DC power from the traction battery pack to the lower-voltage DC power needed to run vehicle accessories and recharge the auxiliary battery.

Electric traction motor: Using power from the traction battery pack, this motor drives the vehicle's wheels. Some vehicles use motor generators that perform both the drive and regeneration functions.

Onboard charger: Takes the incoming AC electricity supplied via the charge port and converts it to DC power for charging the traction battery. It also communicates with the charging equipment and monitors battery characteristics such as voltage, current, temperature, and state of charge while charging the pack.

Power electronics controller: This unit manages the flow of electrical energy delivered by the traction battery, controlling the speed of the electric traction motor and the torque it produces.

Thermal system (cooling): This system maintains a proper operating temperature range of the engine, electric motor, power electronics, and other components.

Traction battery pack: Stores electricity for use by the electric traction motor.

Transmission (electric): The transmission transfers mechanical power from the electric traction motor to drive the wheels.

Charging Technology

Instead of gasoline, you need electricity to propel your car. Where at a gas station you stick a liquid fuel nozzle into your car, for an electric car you put an electrical nozzle for pumping those electrons into your car to be stored in your battery. While you can fuel your liquid petroleum car in five minutes, providing a fill up to an electric car can take a lot longer depending upon the technology utilized.

Before I continue I need to provide an explanation of how charging systems function. When I refer to a charger station, I am talking about the box and cable that connects your car to the electrical grid. The actual charging system that manages the electricity being fed into your battery is in your car.

The charging device that you plug into your car is kind of like a gate. It contains electronics that sense when the cable has been connected to the car. When this is accomplished it closes a relay that allows the electricity to flow into your electric vehicle.

Some might ask why this elaborate system for charging? Well, think about it this way. You really don't want to be connecting a live plug into something that draws a significant current. You could get quite a shock if it was designed this way when your fingers got in the wrong place. As designed, the charge plug and cable are not energized when unplugged. When you connect the plug into the vehicle the car will electronically hand shake with the charging station. Once the handshake is made, the relay in the charging station will open, allowing electrons to flow to the car. When you disconnect the plug, the electricity stops flowing through the cable.

Level 1 Charging
Typically, electric cars come with a 120 volt charge adapter that plugs into your standard wall socket. For a Tesla Model 3 you can count on the car adding 4 miles per hour when using the included 120 volt charge adapter. Doing the math it will take about 12 hours to add 48 miles.

If you are charging from a circuit that feeds multiple outlets and devices, then you risk blowing a circuit breaker. It would be wise to figure out what kind of wiring and circuit breaker you have on your outlet before you opt for level 1 charging. This is especially important when you visit your brother's house on Christmas and ask to plug in. I found out the hard way when I blew the circuit breaker that powered the garage, along with the living room Christmas Tree.

Level 2 Charging
This is what you really want to install. Level 2 stations will typically allow your car to charge quickly. While a Level 1 connector feeds 120 volts into your car, a Level 2 station can feed 240 volts with 60 amps. While you can get by with a Level 1 charge adapter for a plug-in hybrid, or range extended car like the Chevrolet Volt, you really need a Level 2 system for a battery electric car to allow for flexibility.

Not all Level 2 charge stations are created equal. Some charging stations can feed 3.6 kWh into the car, while other stations can feed 7.2 kWh or higher. The maximum power pumped into the car is dictated by the charging system in the car. Generally speaking a 7.2 kWh charging system will add about 25 miles an hour to an electric car. This is a general value, but it is pretty close. I have a Tesla Level 2 charging station in my garage and it adds 44 miles per hour to my Model 3.

Before you go out and buy the highest power Level 2 wall station, make sure your home’s power system can support this. More on this later.

Level 3 Charging Stations
You can't install one of these in the home as they require three phase power. These stations pump a lot of electricity into your car to quickly charge your car. While a Level 2 station can feed about 7000 watts into your car, this monster feeds more than 120,000 watts. We are talking 80% capacity in about a half hour. The problem with this technology, is according to reports, may shorten the long-term life of the battery. Every so often it is ok, but if you want your battery to last you do not want to be doing this daily. Not all cars are compatible with this technology either. Tesla has a different protocol than other auto manufacturers and is not compatible with DC fast chargers other than those at Tesla owned stations. For home use, focus on Level 1 and 2 charging. If you are a renter or do not plan to install a charging station in your garage, this is not a substitute. If you use DC fast charging stations often, you will permanently degrade your battery.


AN EVgo DC fast charging station that supports both CCS and CHAdeMO charging systems.

Charging system types
There are a number of charging system protocols used by electric vehicles to communicate between the car and the charging system. Protocols

J1772
With the exception of Tesla, all electric cars available in the United States use the J1772 interface. This protocol dates back to 2001 and under the first iteration used a square connector. It was revamped and launched again in 2009 with a round barrel connector. While the Tesla connector is incompatible to the J1772 interface, Tesla includes a J1772 adapter to allow Teslas to charge for J1772 charging stations.

Combined Charging System (CCS)
This is a fast DC charging system used by General Motors, Honda, BMW, and Volkswagon vehicles. It is called combined because it uses the J1772 connector in addition to DC leads.

CHAdeMO
This was the first DC fast charge protocol on the market. Today, the protocol is only used by Nissan vehicles. Tesla sells an adapter to allow Model S and X to use CHAdeMO charging stations.

Tesla Connector
Tesla uses its own proprietary charging protocol that is incompatible with other systems. However, Tesla vehicles will accept J1772 connectors with an adapter. Third parties also sell a Tesla to J1772 adapter for charging non-Tesla vehicles using the connector for non-Supercharging charge station installations. Tesla also uses the same connector for DC Supercharging.



While those are the main standards, there have been charging standards that have come and gone over the years. I have included an interesting induction system that was used by General Motors and Toyota in the early 2000s. This year I came across an owner of Toyota RAV4 EV model that went to extreme lengths to use public charging. While his car was not compatible with the J1772 system, he made it so his wall charger was. In his front seat he drives around with a giant wall charger than feed into the J1772 cable, and then into the Rav4 EV.






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