Lithium-ion battery lifespan
The lifespan of a lithium-ion battery is related to the number of completed charging cycles, not the number of charges. A lifespan of 500 cycles for a lithium-ion battery refers to one charge-discharge cycle, not the number of charges.
A charging cycle means the process of a battery going from fully charged to empty and then fully charged again; it is not the same as charging once. For example, if a lithium battery is used up to half its capacity on the first day and then fully charged, and the same thing is done on the second day, this total of two charges only counts as one charging cycle, not two. Therefore, it usually takes several charging cycles to complete one cycle. Each time a charging cycle is completed, the battery capacity decreases slightly. However, this decrease is very small; high-quality batteries retain about 80% of their original capacity after many charging cycles, and many battery-powered products still function normally after two or three years.
Of course, lithium-ion batteries still need to be replaced when their lifespan reaches its end. The "500 cycles" figure refers to 500 charging cycles achieved by the manufacturer. Due to various real-world factors, especially the inconsistent depth of discharge during charging, 500 charging cycles should only be used as a reference for battery lifespan.
Therefore, we can understand it this way: the lifespan of a lithium-ion battery is related to the total amount of charge it receives, not the number of charges. The impact of deep discharge/deep charge and shallow discharge/shallow charge on lithium battery lifespan is not significantly different. In fact, shallow discharge/shallow charge is more beneficial for lithium batteries; deep discharge/deep charge is only necessary when the product's power module is calibrating the lithium battery. Therefore, products powered by lithium-ion batteries don't need to be overly concerned with the process; convenience should be prioritized, and charging can be done anytime without worrying about affecting lifespan.
How long is the warranty period for lithium-ion batteries?
● BMW i3
According to official BMW i3 data, the overall maintenance cost of an i3 is 20-45% lower than that of a conventional electric vehicle. If any cell in the battery pack fails, it can be disassembled and replaced individually. The BMW i3's warranty period in my country is the same as other BMW models: 3 years or 100,000 kilometers (whichever comes first). For core components such as the battery and motor, BMW provides a warranty period of 8 years or 100,000 kilometers (whichever comes first).
●Denza
Denza 4S stores stated that the lithium iron phosphate batteries used in Denza vehicles have excellent performance. Denza's tests show that after 4000 charge-discharge cycles, the battery retains 80% of its capacity. This result coincides with the performance of the E6 battery provided by BYD 4S stores, demonstrating the inherent connection between the two. Denza officially promises a 3-year or 80,000-kilometer warranty for the entire vehicle, a 6-year or 150,000-kilometer warranty for the battery, and a 5-year or 100,000-kilometer warranty for key components; Denza charging cabinets have a 2-year warranty.
●BAIC EV200
According to sales staff at BAIC New Energy's 4S stores, the SK ternary lithium-ion batteries used in the EV200 have a long lifespan, with over 3,000 full charge and discharge cycles and a capacity degradation rate of less than 15%, allowing for up to 10 years of use. BAIC New Energy will also provide a 6-year/150,000 km warranty on all core components (battery, motor, vehicle controller, etc.) for all vehicles, and a 3-year/80,000 km warranty for non-commercial vehicles. Furthermore, the first four maintenance services for all new energy vehicles are provided free of charge.
● BYD E6
According to sales staff at BYD 4S stores, BYD officially offers a 5-year or 100,000-kilometer battery warranty. The lithium-ion battery used in the BYD e6 Pioneer retains 80% of its capacitance after 4,000 recharge cycles, with a battery lifespan of approximately 1.2 million kilometers. Furthermore, the e6 Pioneer and Qin new energy vehicles offer a 6-year or 150,000-kilometer warranty for non-commercial vehicles, with a lifetime warranty on the power lithium battery cells.
