Power battery is a key component of electric vehicles, the car battery health directly determines whether electric vehicles can run normally. This article will take a look at the issues related to car battery health.
1. How to measure car battery health?
It's very simple, just do a test on the battery and show the data indicators, and it will be clear at a glance. In the industry, the battery capacity retention rate is mainly used to characterize the health status of the battery in the whole life cycle. The value ranges from 0% to 100%, and the performance status of the battery is quantitatively described in the form of a percentage.
The battery capacity retention rate represents the ability of the current battery to store electric energy compared with the new battery, and is a characteristic parameter of battery decay. The power battery has undergone a series of strict quality inspections and screenings before leaving the factory to ensure that the car battery health is the best when it is released to the majority of users.
However, with the continuous use of the battery, its internal structure begins to gradually age, the active material decreases, the internal resistance increases, the maximum available capacity and power performance decrease, and the car battery health becomes worse and worse.
According to the current industry standard for power batteries, when the battery SOH drops below 80%, it means that it is time to go back to the battery stores nearby for inspection and maintenance.
Even if two single cells are produced in the same batch, their performance cannot be exactly the same due to the error of the production process. In addition to the internal influencing factors of the battery itself, in daily use, problems such as overcharge and overdischarge caused by usage habits and temperature will also affect the service life and safety of the power battery pack.
This requires accurate assessment of battery capacity retention, constant monitoring of car battery health, prediction of battery life, and escort for daily travel.
2. What will monitor car battery health?
During the operation of the power battery, there is a BMS (battery management system) that monitors the car battery health in an all-round way throughout the cycle. As the intelligent brain of power batteries, BMS is an important link of battery hookup and electric vehicles. A qualified BMS often has the following characteristics:
High sampling accuracy: BMS monitoring technology can monitor all car battery health in real time. With the help of the cell failure mechanism model, real-time prediction of battery performance indicators can be realized, abnormal cells can be identified in advance, and judgments and corrections can be made in a timely manner.
By coupling the battery model and aging model, BMS can estimate battery aging parameters online, obtain material aging information, accurately evaluate battery aging status, and predict the remaining life of batteries. In case of an emergency, give the driver an emergency warning in advance to gain time for safety.
The core algorithm is accurate: BMS accurately estimates the remaining capacity of the battery by detecting the car battery voltage, charge and discharge current, and battery pack temperature, eliminates cumulative errors, and prevents the battery from overcharging and overdischarging. It can extend the service life of the battery, thereby improving the utilization rate of the battery.
High equalization efficiency: BMS's efficient equalization technology can effectively control battery charge and discharge balance, reduce the influence of factors such as self-discharge and battery inconsistency, slow down mileage attenuation, and improve battery mileage and life.
These car battery health precise monitoring technologies can help to detect various problems in the driving process of the power battery as early as possible, and guarantee the daily travel of every electric vehicle owner.
3. What are the influencing factors of car battery health?
As the power battery is used for a long time, the car battery health will be attenuated to varying degrees. Practice shows that car battery health is mainly affected by various factors such as temperature, charge and discharge cut-off voltage, etc.
Temperature: It is generally considered to be the main influencing factor of car battery health. Only when the power battery works within a certain temperature range can it exert its best performance. Once it exceeds the optimum temperature range, the performance of the power battery will be greatly affected, resulting in a decrease in discharge capacity and thus a decrease in cruising range.
High temperature conditions will accelerate the irreversible reaction inside the battery, resulting in the reduction of active substances inside and accelerating battery aging; low temperature conditions will slow down the diffusion rate of lithium ions, affecting the charge and discharge performance of the battery.
Charge and discharge cut-off voltage: Overcharge and overdischarge of the battery will have an impact on car battery health, and inappropriate upper and lower voltage limits will have an impact on the battery. When the battery discharge cut-off voltage is too low, the density of the electrolyte will be greatly reduced, and this low-density electrolyte is very harmful to the porous structure of the battery.
At the same time, excessive discharge will also cause the anode carbon to release lithium ions excessively, causing its lamellar structure to collapse and accelerate battery aging.
Excessive charging cut-off voltage will also increase the internal resistance of the battery, increase the internal heating of the battery, and overcharging will cause lithium precipitation at the anode and increase the corresponding side reactions, which will affect the capacity and aging of the battery.
Current capacity: The current capacity of the battery is one of the main parameters that characterize car battery health. When the current capacity of the battery is lower than 80% of the rated capacity, it means that the aging and degradation of the battery including all aspects of performance are serious.
The degree of attenuation of battery capacity directly affects car battery health. When the durability of the battery decreases, the capacity of the battery also decreases, which shortens the life of the energy battery and shortens the cruising range of the vehicle.
Battery internal resistance: When working, a part of the electric energy will be lost by the internal resistance, and the lost electric energy is proportional to the internal resistance of the battery. For lithium-ion batteries, after multiple charge and discharge operations, due to its internal chemical changes, the internal resistance will gradually increase, and the corresponding internal resistance loss will also gradually increase, which results in a decrease in the available energy of the battery.
4. Tips for car battery maintenance
Therefore, in daily use, in order to protect car battery health, we can pay more attention to these car battery maintenance tips:
Choose a suitable parking/charging environment: avoid long-term exposure of the vehicle to the hot sun, and avoid charging in extreme high-temperature environments; it is recommended to park the car indoors in winter to avoid the car being unable to charge and discharge normally due to low temperature.
Maintain good driving habits: During the driving process, try to accelerate as smoothly as possible to avoid sudden increase in current and overheating of the battery pack caused by sudden braking and acceleration. Allowing electric vehicles to run under mild conditions can effectively extend the mileage and service life of the power battery.
Shallow charge and shallow discharge: During daily use, avoid "recharging after use, charging from 0% to 100% at one time", as over-discharging of the battery will cause irreversible damage to the internal materials and structure of the battery.
But overcharging will also affect car battery health. Therefore, it is recommended not to fully charge the battery, and not to fully discharge it. It is more appropriate to keep the remaining capacity of the battery within the reasonable range recommended by the manufacturer for daily use.
So how do ordinary users understand car battery health? Soon there will be a technology for vehicle and car battery health detection using big data. Users can check the test report at any time on the mobile phone, and the report can be updated regularly, so that various hidden dangers of the vehicle can be discovered early, repaired and maintained early, and the safe travel of the car owner is ensured.