For consumers, when purchasing a new energy vehicle, the most concerned topic is its endurance. Now, with the continuous upgrading of technology, the range of ordinary electric vehicles is also increasing, and the range of ordinary electric vehicles has reached the level of 400-500 kilometers. In addition to battery life, another factor that affects consumers' decision to purchase a car is the charging speed.
Generally, cars will be labeled with "slow charging time" and "fast charging time", where fast charging time is the biggest competitive point for major automotive companies. The shorter the fast charging time, the better sales volume, and the higher attention. Since fast charging is so good, why should we charge it slowly? Although fast charging can shorten the charging time, it also causes significant damage to the battery. Isn't it a bit surprising that fast charging is actually harmful to batteries? Today, let's talk about this topic.
The difference between slow charging and fast charging of automotive batteries:
First of all, before solving this problem, let's understand the difference between slow charging and fast charging. As we all know, slow charging uses alternating current, and the time to fully charge is generally 6-8 hours. In this charging mode, the battery suffers minimal damage. Compared to slow charging, fast charging is an emergency charging method that uses high-power direct current (also known as AC fast charging). This DC charging voltage is generally greater than the battery voltage, and a large number of current ions will flow from the positive electrode to the negative electrode of the battery at a very fast and efficient speed, completing the process of rapid charging.
The principle of quick filling is similar to a small bottle that was originally filled with the smallest amount of water. To reduce time, if you open it to the maximum, you can certainly fill a lot at once, but such a large amount of water also has a significant impact on the bottle. In other words, under long-term rapid charging conditions, the actual voltage the battery is subjected to is very high, and under such high voltage conditions, the battery will definitely be affected.
What is the impact on the use of fast charging for automotive lead-acid batteries and lithium ternary batteries?
After discussing the difference between slow charging and fast charging, we still need to understand batteries. Currently, the batteries of electric vehicles are generally lithium batteries and lead-acid batteries. Different batteries have different power generation mechanisms, and their sensitivity to rapid charging also varies greatly.
For example, when charging a lead-acid battery, the internal electrolyte will gradually react and decrease, resulting in a gradual decrease in battery capacity and a decrease in battery endurance. Although slow charging can also lead to a reduction in battery capacity, slower charging can cause minimal damage.
After talking about lead-acid batteries, let's take a look at the new energy vehicles on the market today. Most of them use lithium ternary batteries, which are characterized by light weight and high power. However, there are also certain drawbacks, that is, if the heat is out of control during use, it can easily cause fire and explosion. To get to the point, when the vehicle is fast charging, it will momentarily input a relatively large amount of current to the battery, which will affect the battery's restoring ability. As the battery's reduction ability decreases, the vehicle's battery decay rate will increase, which in turn affects the battery's endurance and overall performance.
At the same time, the charge and discharge rate of lithium batteries is also a matter of concern. A battery with a rated capacity of 100Ah is charged and discharged at a rate of 0.2C at 20A. Generally speaking, the charging current of lithium batteries is set between 0.2C and 1C. The higher the current, the faster the charging is. However, the more severe the heating phenomenon of the battery, and even lead to spontaneous combustion.
Role of BMS battery management system on batteries:
Although there are certain hazards to fast charging batteries, we need not worry too much. Because, in order to reduce the damage of fast charging to the battery, engineers have invented a very important component - the BMS power management system. For electric vehicles, BMS is the core component of fast charging. The main role of BMS is to intelligently manage and maintain each battery cell, prevent overcharge and discharge, extend battery life, and monitor battery status
In short, BMS uses intelligent control algorithms to adjust the charging current pulse width, interval time, and discharge current pulse based on the current state of the battery, modulate appropriate current and voltage to complete charging, and reduce the damage caused by rapid charging to the battery as low as possible, so the damage can be ignored in a limited time.
In general, any battery that uses fast charging will damage the battery. However, if the battery density, material, temperature, and battery management system of an electric vehicle are designed very well, then this damage will be within a reasonable range. In order to prolong the battery life, try to use fast charging as little as possible, and do not over charge. To protect the battery, it is better to charge it more slowly.
At the end of the article, I would like to share a little knowledge about extending battery life. "If conditions permit, we try to use slow charging to minimize battery damage.". Occasionally traveling on weekends or driving long distances, there's nothing wrong with using two to three quick recharges a week. In addition, if conditions permit, it is best to ensure that the vehicle is fully charged once a month, in order to facilitate the long-term battery life.