Author / Yu Lei
In recent days, a report by CCTV Finance on "new energy vehicles are charged frequently in winter, and public charging piles basically rely on "grabbing"" has once again aroused concern about the mileage anxiety of pure electric vehicles on the Internet.
The report pointed out that the activity of the power battery in the low temperature environment decreased, the net discharge rate decreased, the capacity was affected, and the frequency of charging needed to be increased. A part-time ride-hailing driver interviewed said that what was originally a one-day car became at least twice a day in the winter.
In fact, low temperatures are still the biggest killer of electric vehicle endurance.
The American Automobile Association (AAA) once mentioned in a research report that the ideal operating temperature of lithium-ion batteries is about 70 °F (21 °C), and too high or too low temperatures will affect their charge and discharge performance, capacity characteristics and cycle life.
In other words, low temperature not only will the battery inexplicably lose power, charging and discharging will also reduce the power, it is difficult to support the normal operation of the motor. If you do not actively reduce to safe power, you will also face the risk of thermal runaway.
At present, in order to make electric vehicles work normally at low temperatures, car companies generally ensure their low temperature performance through battery thermal management systems, but the way of electric heating often means that the power consumption is greatly increased, which directly affects the mileage.
In addition, electric vehicles have another major power consumption equipment in winter - air conditioning, the current mainstream PTC heater power of about 6-8kW, which means that full power work for an hour to consume 6-8 kWh of electricity.
In the face of this problem, the current car companies are also gradually switching to heat pump air conditioning to improve energy consumption. In this process, Tesla and BYD will also open up multiple domains such as cockpit, electric drive system, power battery, etc., so that the heat pump can exchange heat between multiple domains in the car in addition to the traditional way of heat exchange with the outside air, so as to achieve a more efficient tempering and energy saving effect.
Recently, Auto Byte came to Shenyang, Liaoning Province, to conduct winter tests on BYD's first dolphin equipped with this heat pump solution. The specific test model is a fashion version priced at 108,800 yuan after subsidies, using a 70kW front permanent magnet synchronous motor, a 44.9kWh lithium iron phosphate blade battery, and a NEDC cruising range of 405km.
Temperature 1 to -4°C, endurance achievability 70.9%
The test route chooses to start from the hotel next to the second ring road, enter the fourth ring road through the airport highway, leave the fourth ring road at the exit of Shenliao Road, enter the second ring road through the city open road, and circle to the end of the Shengjing Grand Theater. The whole road condition changes about the following: high-speed ring road urban open road + small section of expressway loop.
The test departure time is about 8:31, the outside temperature is 1 °C, and it ends at about 11:54, and the outside temperature is -4 °C. The total time was 3 hours and 23 minutes, with about 1 hour in between for still shooting.
During the test, including the shooting period, the vehicle was started throughout the whole process, maintaining a warm air of 24 ° C, opening ac, external circulation, and 1 wind block, simulating the working conditions with the highest comfort in the real scene of the car, but the energy consumption was also high. At this time, the heat pump should work with high power and for a long time, so that the cold air entering the car through the external circulation rises to the target temperature.
The most commonly used setting is selected for driving mode: Economy mode (there are three driving modes of sports/economy/snow), and larger feedback (there are two kinetic energy recovery models). During the test, there is no deliberate energy saving, speed up as soon as possible, try to keep up with the front car, and get close to the speed limit.
(Schematic)
It should be noted in advance that this test is dominated by relatively high-speed loops, which are relatively economical road conditions for fuel vehicles, but not the economic conditions of electric vehicles. The latter does not have a gearbox, it is necessary to cover the entire working area with the motor speed, and the acceleration and deceleration of the high rotation stage on the loop road is already in the range where the motor is running at full power, but the torque continues to decline, and it is necessary to consume more power to accelerate and overtake.
After the test, according to the total mileage of the table display, the actual driving is 107km (4174km-4281km), the endurance of the table is reduced by 151km (405km-254km), the endurance rate (compared to THEDC) is about 70.9%, and the energy consumption is about 15.6kWh/100km. Moreover, during static shooting, the energy consumption of keeping the vehicle energized and the 24°C warm air on for about 1 hour is also evenly distributed, and the real achievement rate will be higher.
This data can be called excellent in electric vehicles that are often cut in the winter. In particular, it is necessary to consider that the gap between the sub-zero low temperature environment and the NEDC room temperature test during the winter test is even more rare.
According to the requirements of GB/T 18386-2017 "Electric Vehicle Energy Consumption Rate and Mileage Test Method", the test not only does not need to open auxiliary equipment such as air conditioning or heating windows, but also simulates the road environment indoors through a bench and blower, and the temperature is maintained between 20-30 ° C, which is the ideal working range of the power battery.
DiLink 3.0: Rich application ecosystem
In addition to reaching a 70.9% endurance achievement rate, BYD Dolphin's car and machine system also left a deep impression on us. Although its starting price after subsidies has reached a lower than expected 93,800 yuan, it is still equipped with a DiLink 3.0 intelligent network connection system for the entire system.
Among them, the introductory vitality version is DiLink Lite, and the rest is DiLink. The former is a low-end version, but only lacks speech recognition and a motorized rotating screen, while the latter increases the screen size from 10.1 inches to 12.8 inches while adding features.
DiLink 3.0 is equivalent to an Android tablet, the interface, functions and operation methods are basically the same as the mobile phone, there is no difficulty in getting started, and there are three main control keys at the bottom of the same Android. The built-in Qualcomm Snapdragon 660 chip did not appear in the application of double opening and running commonly used applications such as iQiyi and AutoNavi Maps.
Rotating the screen is already a label for BYD today, which can be controlled by turning the screen electrically in the steering wheel or buttons on the screen, or it can be controlled by voice commands to "rotate the screen". It is also commendable that when using the voice command of rotating the screen, there is no need to wake up the car in advance, which enhances the convenience.
Rotating the screen may not seem useful at first, but in running applications such as K song and douyin that originally need a vertical screen, or horizontal screen applications such as iQiyi and Tencent Video, you can achieve a matching degree and use experience that is significantly higher than that of a fixed screen.
In addition, by rotating the screen, you can build an application ecology more efficiently. Such advantages have been shown in DiLink 3.0, and the ecology of its app store is almost the same as that of mobile phones, which can be downloaded and installed at will.
Despite facing such a large-scale application group, DiLink 3.0 is still difficult to make each application achieve targeted UI and screen portrait state adaptation, such as automatically cutting the vertical screen after the video application enters, and cutting the horizontal screen when playing the video. However, first paving the application ecology as much as possible, and then gradually optimizing it in the later stage, is obviously the right path. This is more conducive to playing to the advantage and ensuring the user experience.
However, for the most commonly used AutoNavi maps, DiLink 3.0 also pays more attention to the special needs of the car. When the app is running in the background, even if it is not in the navigation state, it will also display information such as speed and front camera through a floating window, and the position supports arbitrary drag, so as to avoid obscuring the information of the current page, and can also click the corner mark to close.
In addition, DiLink 3.0 also supports left and right split screens. You don't need to enter the corresponding function in advance, click the split screen button in the resident control bar below to select the second application, which has fewer steps than the mobile phone. In addition, the two apps also support interchangeable positions and can return to full-screen mode by tapping the "X" or dragging the divider to the side.
In general, in an environment of 1 to -4 ° C, BYD can achieve a 70.9% endurance achievement rate with lithium iron phosphate blade batteries, and the results can already be called excellent. This is also because it relies not only on the technology of heat pump, but also on the heat pump solution of the e3.0 platform to open up multiple domains.
At present, most heat pump models are heat exchanged with external air to heat up the car, and the efficiency will be greatly reduced in the face of low temperature environments, but BYD has improved the scope of application by connecting the electric drive and battery in the car to the heat exchange range. In addition, in the face of extreme cold conditions, BYD can also generate more waste heat by reducing the efficiency of the drive motor, and the heating pump is exchanged.
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