How to balance ultra-fast charging and battery life?

　　This question is interesting:

　　Why do we pursue high power? The speed of charging represents a sense of freedom, which under certain conditions can directly determine how consumers feel about a car.

　　Under the demand of customers, fast charging will be abused, which means that they will use this convenient and fast charging method as much as possible. When continuous fast charging accumulates, it will damage the battery and cause conflicts between manufacturers and consumers. opposition.

　　I think in the future, we need to use actual vehicle use and historical data to provide a balance between consumers and vehicle warranty and vehicle residual value. To put it bluntly, we need to use software to let consumers know how many times they can go super fast. Opportunities to recharge and how to use them.

　　1) Porsche and BMW fast charging test

　　The two companies conducted a research project to see whether the entire charging electrical system could withstand this limit and the extreme endurance of the battery. They used a modified Taycan prototype equipped with 90 kilowatt-hours of electricity to test 800V/400kW charging. .

　　Porsche's target is 450 kilowatts, and the tested charging speed can reach 100 kilometers of cruising range in 3 minutes. The steady-state charging power that Porsche can currently achieve on Mission E should be around 200 kilowatts; the ultimate charging speed in the extreme test has reached 400 kilowatts, which does not consider the durability of the entire system at all, but it is suitable for drivers who need emergency charging. Players can bring extra surprises (at this speed, you can just smoke a cigarette and run away).

　　2) The consequences if fast charging is used 100%

　　There is a case in Brother Shen Fei's blog post "Two Unknowable Things in the World". Following this case, you can also find out the usage of this car.

　　In August 2016, the Ehawk traveled 312,600 kilometers (194,239 miles), and the estimated mileage of the vehicle began to become extremely inaccurate. The Tesla service center determined that there was an internal imbalance in the vehicle's main battery and decided to replace the battery; in January 2018 , the total mileage of the vehicle reached 324,044 miles, which means that the new battery has been used for 129,806 miles (208,900 kilometers). The Tesla service center diagnosed that the main battery was not working properly, replaced it with a 90kW battery, and upgraded the eHawk to 90D specifications (8 years without mileage limit).

　　Tesla's diagnosis is as follows: This customer charged directly from extremely low bills to 95-100%. However, the first battery that was removed and tested in detail only lost 6% of its power, and the second battery dropped by 22%.

　　Battery degradation over the course of the first 194,000 miles was ~6% with multiple supercharges a day to 95-100%. Between 194,000 and 324,000 miles Tesloop experienced battery degradation of ~22% .

　　From the perspective of capacity, the difference in internal resistance of the battery core makes it impossible to use the battery core.

　　Found internal imbalance in HV battery due to consistent supercharging to 100% from a low state of charge (SOC) without any rest periods in between.

　　We can also see from the above that Tesla’s unlimited mileage gives customers three batteries. No matter how expensive this car is, it has a total of 90kwh*3, plus fast charging and free electricity, this American brother has made a fool of himself. How awesome. I also don’t understand why Tesla comrades don’t give such customers this opportunity.

　　3) How to balance

　　We actually need to consider the ideas of leaders of various departments and make our products competitive. The former needs to consider various situations to ensure that the company's interests are not lost (don't create loopholes that lead to batch claims and various commitments that cannot be met), while the latter needs to consider the actual use of users and also needs to solve the problem. The pain points of actual car owners help them understand that the battery is actually their own, and misuse is actually not beneficial to both parties. From the perspective of protecting the battery, restrictions can only be imposed in all aspects.

　　I think the way to solve the problem is to start with data, software and letting users better understand the actual situation:

　　➤Record user usage and provide early warning at the vehicle application layer

　　➤Divided into different modes, users can try their best to use the battery's power, discharge and fast charging capabilities in scenarios where they are really needed, but in some unnecessary situations, they can keep it for use. If a customer really wants to drive home for the New Year, and it is only once a year with the whole family, we must create a Spring Festival home mode in the software to make him feel the greatest sincerity.

　　➤In the verification stage, abandon the original OK and NOK models. I think the battery method is also obvious now. Limited suppliers, limited designs, all requirements will eventually bring costs, and we can find out its true number of times. , and figure out how we should use it (what kind of Current will not cause permanent damage, and how many times it can be used).

　　Summary: In the macro context of subsidy removal, from the perspective of cost control, we may have to abandon the original thinking model, try our best to find something that can be given to customers, and pull it out before customers finish using the battery. return.

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