Fast charging and slow charging of lithium-ion batteries are relative concepts. Generally, fast charging is high-power DC charging, which can charge the battery to 80% capacity in half an hour. Slow charging refers to AC charging, which takes 6-8 hours. The reason why fast charging is faster is due to the difference in charging voltage and current; the higher the current, the faster the charging. When the battery is almost fully charged, constant voltage is used to prevent overcharging and protect the battery.
Slow charging of lithium-ion batteries for electric vehicles uses relatively low charging current and power, which is better for battery life and lowers charging costs during off-peak hours. Fast charging uses higher current and power, which can significantly impact the battery pack and its lifespan. Fast charging also requires additional equipment, such as AC/DC converters, increasing costs.
What are the dangers of fast charging lithium-ion batteries?
1. Lithium-ion battery charging equipment has high installation requirements and costs, and uses high current and voltage, which can cause significant impact on the battery in a short period of time. Long-term fast charging can also affect the lifespan of lithium-ion batteries.
2. Fast charging injects a large current into the lithium-ion battery instantaneously. Frequent use of fast charging mode will reduce the battery's recovery ability and decrease the number of charge-discharge cycles.
3. Fast charging places high demands on the quality of lithium-ion batteries, significantly reduces battery life, and noticeably lowers safety. Therefore, it should be avoided unless absolutely necessary.
4. The working principle of fast charging for lithium-ion batteries is: first, an increase in voltage, and second, an increase in current. Fast charging also uses this principle, so a large current causes the battery to react at an excessive speed. This reaction generates a lot of heat, which, due to internal resistance and exceeding the temperature limit, can damage or prematurely age the battery.
