The most direct impact of "power failure" is the discount of cruising range. Not long ago, a Sichuan user obviously felt that the cruising range dropped after OTA. The battery capacity of Tucki P7 four-wheel drive performance model is 80.9 degrees, and the cruising range of WLTP is 430 kilometers. After one year and three months of use, the actual charging capacity is only 66.3 degrees. If calculated in proportion, it should be able to charge nearly 73 kWh, while the WLTP of the vehicle was fully charged at that time.
Today, "lock power" is not a case. Previously, Weimar Automobile, Beiqi New Energy EX360, GAC Aian S, GAC Toyota iA5, Tesla Model S and other models have all appeared. The cruising range of pure electric vehicles is an important index to consider the price of vehicles. Discounting the cruising range is the most intuitive way to reduce the user experience, and the vehicle price will also be greatly affected.
"Power off" changes the threshold of battery energy output through the battery management system, delimits a new voltage output range, and then limits the battery capacity. At present, most vehicles without power supply have not given a very reasonable explanation, but doing so can really improve safety and prolong service life.
The problem of "power locking" is basically a car equipped with a ternary lithium battery. There is not much breakthrough in the development of lithium batteries today. Most lithium batteries in the market are basically composed of positive electrode, negative electrode, electrolyte and diaphragm. When the battery is discharged, the lithium ions stored in graphite are released into the electrolyte, the lithium ion concentration of the negative electrode increases, and the lithium ions will move to the side with low concentration, that is, the positive electrode, and the excess lithium ions will be absorbed by the positive electrode to maintain dynamic balance. If it is charged, the opposite is true.
But the charging and discharging process of lithium battery is not perfect. No matter charging or discharging, electrolyte will be consumed, and the positive electrode will rupture and the negative electrode will collapse, which will reduce the storage and transportation of lithium-ion media, and then the capacity will decrease. So we can see that most pure electric vehicles have "daily" and "long-distance" modes. The daily mode is not fully charged, and the maximum power is controlled at 90%, which is beneficial to prolong the service life. Besides, electricity is used too much.
The most serious problem of battery pack is thermal runaway, which will lead to fire and explosion of battery pack. Thermal runaway of battery pack mainly includes mechanical shock, high temperature and electrochemical thermal runaway.
Mechanical shock and high temperature can be solved by adding better protective devices and liquid cooling systems, while electrochemical thermal runaway is even more fatal. As mentioned earlier, with the increase of battery life, the capacity of the battery will decrease after the positive electrode breaks and the negative electrode collapses. In the process of fast charging, the internal reaction speed of the battery will be very fast, which will be accompanied by the sharp increase of temperature and the internal resistance will increase with the increase of battery power. If the battery capacity is limited, these risks will be greatly reduced and the service life of the battery can be extended.
In the past, when battery management was not so intelligent, many people encountered the problem that the lithium battery of mobile phones expanded due to overcharge. With the increase of service time, the actual capacity of the battery will gradually decrease. At that time, there was no good way. A large number of unqualified chargers often caused occasional fire and explosion problems.
The battery capacity of pure electric vehicles ranges from tens of degrees to hundreds of degrees. The energy contained in a 50-degree battery pack is 180000000 joules, which is basically equivalent to the energy released by 42 kilograms of TNT explosives, but the reaction speed is not as fast as that of explosives, but it is still terrible after the heat is out of control, which is a fatal problem for users. For manufacturers, the aging heat loss of the old model will also cause huge compensation problems, so the power is locked.
China is in the era of great development of new energy vehicles. At present, the charging speed of pure electric vehicles can not be compared with that of fuel vehicles, and only by improving the capacity of battery packs. For users, the health of the battery pack is the core of the core. "Locking power" is equivalent to sacrificing user experience to improve security. At the same time, it also reflects the lack of technology of manufacturers, which can not give consideration to safety and battery life. Such products should not be paid by consumers.