The endurance of electric vehicles in the winter low temperature state is only 50% of the nominal endurance, which is the norm, and the recent winter pure electric vehicle test of the car emperor has also confirmed this. At extreme test temperatures of -20°C, only 10 of the 40 test vehicles ended up running to more than 50% of the nominal endurance. In the daily use environment in the northern winter, the actual pure electric vehicle users can generally only drive 50%-60% of the mileage, so winter endurance anxiety still plagues pure tram owners. Under the premise that there is no revolutionary breakthrough in battery technology, how to solve the problem of shortening the mileage in winter has become a key area for car companies.
There are two major factors that affect the winter battery life of electric vehicles
Before solving the problem, analyze the problem and what causes the winter mileage decline of pure electric vehicles. At present, there are two main reasons: the performance of lithium batteries at low temperatures is reduced; the heating equipment on the car increases energy consumption.
At present, pure electric vehicles generally use lithium batteries as a power source, and the conductivity of the electrolyte inside the battery, the conductivity of the negative SEI film, and the rate of chemical reaction will be reduced at low temperatures, and the final appearance is that the capacity and charging and discharging performance of the battery are significantly reduced. The method of coping with the cryogenic freezing of the electrolyte is also very simple, heating the battery. This brings us to the next problem, increased energy consumption.
Electric vehicles have many components that consume electrical energy due to heating needs in winter, including battery insulation, interior heating, seat heating, and steering wheel heating. And there is only one battery in the car, and all these appliances are competing for power with the mileage.
In extreme environments, the loss of electrical energy due to the above two factors will reach 50% or more of the total capacity of the battery. Ensuring the mileage in the low temperature environment has become one of the important problems that electric vehicle companies need to overcome urgently. So how do the head electric vehicle companies do it?
Extract heat with an efficient thermal management system
The 10 cars that performed well in the Winter Test have one thing in common, they all have an excellent thermal management system. For example, the thermal management system is like a meticulous accounting room, he collects every bit of heat in the whole car and uses it where it is needed, such as the heat generated by the motor is transmitted to the car to heat up the tram and cabin, and the extra heat generated by other high-power appliances is also collected and utilized. In addition, excellent thermal management systems have a common feature: heat pump air conditioning.
Most of the heating components of electric vehicles are PTC boards, which is an electric heating component, just like hair dryers, which generate heat by consuming electrical energy, characterized by how much electricity is used to generate how much heat, and the efficiency is relatively low. The heat pump grabs heat from the outside environment, and as long as it is not in the absolute zero degree of -273 ° C, it can obtain heat. The heat pump is designed based on the second law of thermodynamics, which can transfer heat from the low temperature environment to the high temperature environment, that is to say, it can extract heat from the environment where the temperature is below zero and transport it to the car with a temperature of more than 20 ° C, making the outside world colder and the car warmer. Since the heat pump does not directly generate heat, it is only carrying heat, so its energy consumption is less than half of the PTC board. Therefore, heat pump air conditioning has become an important prop for electric vehicles to save the winter mileage, but because of its high cost, Tesla and Porsche Taycan are optional. Even so, the heat pump air conditioner is not perfect, and its working principle means that the lower the outside temperature, the less heat it can grab, and the work efficiency decreases with the decrease of temperature. At very low temperatures, the efficiency of the PTC board is higher.
Is there a thermal management system that does both? This brings us to HiPhi X's complex thermal management system.
HiPhi X thermal management system that eliminates shortcomings
From the schematic diagram of the thermal management system used by HiPhi X, its core is a set of indirect water medium heat pumps, which obtain heat energy from the external environment, power battery, motor system and then transmit it to the power battery and cabin through the internal water circulation system. In addition, it has a set of PTC auxiliary heat source, which directly supplies the battery and cabin with the heat generated by PTC at very low temperatures. Under the overall management of the thermal management system, the coordination of heat pumps and PTC is in the most efficient state.
From the perspective of design structure, hiPhi X thermal management system can be described as costless, and its complexity ranks among the best in pure electric vehicles. Theory is theory, how does this system perform in practical applications?
Warm air comes faster than fuel vehicles
To measure whether a thermal management system is good or not, my most intuitive feeling comes from how long it takes to warm the car. In terms of practical experience, the recent Beijing daytime temperature is about 4-5 °C, the night is as low as -4 °C, in such a temperature under a fuel car parked overnight, the cabin temperature to reach more than 16 °C comfortable temperature takes at least 8-10 minutes, but also have to endure the cold for 1, 2 minutes in the hot car stage, wait for the water temperature to rise and then open the warm air, otherwise the water temperature can not come, the warm wind is also a biting cool breeze. In the same situation, the HiPhi X actually warmed up in the car in only 5 or 6 minutes, and the warm air came faster than the fuel car. If it is in the driving state, the heating speed will be faster. HiPhi X uses a more complex dual-waterway design, the cooling circuit of the battery and motor system is crosslinked with the waterway of the heat pump through a heat exchanger, and the waste heat of the power system can be quickly introduced into the cabin into warm air during driving and charging.
It is worth mentioning that hiPhi X does not have the concept of "hot car", and the thermal management system will use the external power supply of the charging pile to preheat and insulate the battery in the state of accessing the charging gun. As long as the travel time can be preset through the mobile app, the vehicle will automatically raise the cabin temperature to a comfortable temperature before traveling. At the same time, it also gives priority to maintaining the battery power, which is equivalent to indirectly increasing the cruising range of the whole vehicle.
Every year, we go to Yakeshi's electric vehicles and maintain 80% of the winter battery life
The HiPhi X in my hand has a nominal endurance of 550 kilometers (NEDC conditions), and can generally drive about 450 kilometers of actual endurance in summer use. The cruising range in the winter environment of Beijing is maintained at about 380 kilometers, which is equivalent to 70% of the nominal endurance. In contrast, most of the other electric vehicles I have driven in the same environment have a range of about 5-6 folds, which shows that Gaohe's thermal management system regardless of cost is indeed effective.
Back to the winter test data of Chedi, at the temperature of -20 ° C in Yakeshi, HiPhi X threw out an actual endurance of 291.2 kilometers, and the endurance achievement rate was 52.95%, which was a pretty good result. In fact, it is not surprising that HiPhi X has achieved such results, because Yakshi is a place that it is familiar with.
In 2020 and 2021, HiPhi X has twice conducted winter extreme cold engineering tests in Yakeshi, collecting a large amount of low temperature test data. The endurance is only a small part of the low temperature test, and there are also low temperature durability, low temperature reliability, ice surface instability, snow dynamic performance, and even door ice breaking ability and other items of testing. It can be seen that Gaohe attaches great importance to the performance of vehicles in low temperature environments.
Write at the end
It is difficult to do a good job of high-end electric vehicles, because high-end is not stacking technology and configuration, these are only appearances, and even the best technology cannot solve the actual problems. The real high-end is to create more value for users by solving problems and pain points, so starting from the user's point of view is the fundamental way to create high-end. Ding Lei once said to the team: "If your department is not directly to the user, or there is no direct user point, then your department should consider refactoring, you say that there is no point in your business that is related to the user, then your department should be reconstructed, I will either withdraw you or merge you." It can be seen that for the concept of high-end, Gaohe has a deep understanding.
HiPhi X is a figurative expression of this understanding, and this expression has also been echoed by users. Since its deliveries began in May, the HiPhi X has delivered more than 3,300 units, ranking among the high-end electric vehicles priced at more than 500,000 yuan, just one step away from the top of the list. Users respond to Gaohe's efforts in this way by delivering volume, and Gaohe's next step will be more solid.