[EN] Let's talk about: Basic understanding of electric car
Today I will start a new series of articles intended to provide you with all the relevant info necessary to make important decisions that hopefully will change your life in better and help us reduce the pollution and someday into the future even breathe safe on the streets.If you are driving for a while probably you are familiar with notions like gas, diesel, petrol engine or internal combustion engine (ICE), HP or horse power (even today we are still using this archaic term). When you switch to an electric car all this terms and many others are useless and my advice to you is to completely forget about them and not try to thing about electric cars in terms of fossils because in electric cars world there are no gas pumps, liters of fuel, gearbox, clutch or gears to change.
Most important componentsThinking in simple terms, an electric car has one or more engines, some will have up to three engines or even four in to the future, a traction battery or high voltage battery (HV Battery), a 12V battery required by law for lights and other accessories, a charging port and an onboard charger. All this components will seem new for you and is better to have a basic understanding of what each of them does, preferably before you buy the car.High voltage batteryHigh voltage battery usually has a nominal voltage close to 400 volts or 800 volts (in Europe we have 230V for single-phase connection or 400V for three-phase connection) on some cars, and contains smallcylindricalorpouchcells connected in groups in series or parallel in order to give you the power you need. In terms of design and form you can think to this cells like similar to laptop or phone batteries but with completely different properties especially when we are talking about longevity and power provided. The high voltage battery is designed to function even when some of the cells are not working properly or in some cases even when a group of cells is not working at all. In case of a fault you will have some power limitations but the car usually still function and the vast majority of users will not notice if a cell from high voltage battery is defect but please note that this is highly dependent on battery pack design.During charge and discharge of the high voltage battery, the cells are heating up and usually the battery pack is designed to include a thermal management system capable of cooling and heating up the high voltage battery, but please note that there are also electric cars without a thermal management system. The better thermal management system your car has, the longer your high voltage battery will last with less capacity degradation and in my opinion HV thermal management system is a must for all electric cars.Most important term you need to know about your HV battery is capacity. The higher the capacity, the higher the number of kilometers you will be able to travel and also the power that will be available to your car. HV battery capacity is expressed in kilowatt hours – kWh.HV battery starting from the first use will start to slightly degrade and lose some capacity and this will accumulate in time. For most of the normal owners this will not be visible even after many tens of thousands of kilometers.There are also many thing you can do to reduce the degradation and prolong the life of your HV battery, but the most important ones in my opinion are:• Do not charge your car to 100% if you do not need to• For daily use set a charging interval from 30 to 80%, or from 25% to 80% or just what is suitable for you without charging to 100% or discharging to less than 10 - 15%• Do not ever leave your car charged to 100% for long periods of time (days, weeks or months). If you require 100% of your HV battery, be sure you leave as soon as possible after the charging is finished.• In cold climate try to preheat your car or leave your car plugged in. In some cases this will also preheat your HV battery, in other cases programing your charge while your car is plugged in, will start preheating your HV battery.• Charging your car to 100% or discharging it to less than 10 -15% from time to time is ok, but doing this every day is notLike every other type of battery, HV batteries deliver and can be charged only with direct current – DCMore information about how the HV battery is functioning you can find hereDrive unitAn electric car is powered by an electric motor and this together with the inverter and gear reduction box form the drive unit. There are many types of electrical motors used today, some are more efficient but are using rare materials (permanent magnet motors), other are less efficient but use no such materials (induction motors). On some cars you can even find both types of motors and a clever algorithm is controlling the power and is making the car more efficient. Image credit: Oleg AlexandrovWhat is important for you to understand is that the electric motor from your electrical car is always powered by alternating current – AC – and the power consumed by the motor is expressed in kilowatts - kW. The power of the motor/motors is actually the power of the car and you will find this in the specifications of the car.The component responsible with conversion of direct current – DC – provided by the battery, in alternating current – AC – used by the motor is the inverter.One other important function of the drive unit is regenerative braking. Each time you press the brake or just lift your foot from the accelerator, your car motor will start transforming the motion of the car in energy and this is converted by the inverter in DC and charged back into the battery. On some cars you can set how aggressive the regenerative braking should be or not use this function at all if you don't like it.Nowadays electric cars have also a special drive mode called B mode. In this mode the regenerative braking is more aggressive and you will recover more energy each time you brake.Charging types/charging plugsAn electric car can be charged in two ways:• DC charging – In this case the conversion from AC to DC is done by the charging station and usually this is the faster way to charge. This type of charging is not suitable for charging at home do to the high cost of the station. Using DC you can charge your car with power starting from 20kW and up to 350kW, depending on how fast your car can charge.• AC charging – In this case the conversion from AC to DC is done by the car, the charging station is just a contactor, a small electronic controller and protections according to safety requirements applicable. This type of charging is usually used for slow home charging or is available in places where you will spend some time with other activities, like hypermarkets. Using AC you can charge your car with power up to 22kW, depending on the OBC included in the car.In Europe for DC charging we use two types of plugs:• CCS – Combined Charging System Image credit: Hadhuey• CHAdeMO – There are not many cars that use this standard and Europe is adopting on large scale CCS as the common standard. My recommendation for you is to not buy a car that uses this standard at this time because there are already charging stations that do not use this and in the future the vast majority of new charging station will not support this standard anymore. Image credit: NickFor AC charging there is only one standard used in Europe: Type 2. Image credit: SladenOBC - onboard chargerOnboard charger is responsible for converting AC from the grid to DC required by your car HV battery for charging. This component dictates how much power can you use on an AC charging station. OBC can be single-phase and this will allow you to charge with power up to 7.6kW, or can be three-phase and allow you to charge with 11 or 22kW.Usually for the cars that have an DC charging option, the OBC is designed to be used at home, is single-phase and is allowing you to charge with low power.My advice to you: if you have a DC charging station and your car is DC capable, do not use AC on long trips because you will spend a lot more time and there are others that depend on AC charging stations.Published by Marius Şerban at 15:26 on 25.04.2020 [EEST]