Knowledge about lithium battery life

- Aug 07, 2019-

Lithium-ion batteries can only be charged and discharged 500 times?

I believe that most consumers have heard that the life of lithium batteries is "500 times" and 500 times of charge and discharge. More than this number of times, the battery will be "dying down". Many friends are trying to extend the life of the battery every time. Charging when the battery is completely exhausted, does this really extend the life of the battery? the answer is negative. The life of a lithium battery is "500 times", which means not the number of times of charging, but a period of charging and discharging.

A charge cycle means that all of the battery's charge is from full to empty, and then from empty to full, which is not the same as charging. For example, a lithium battery used only half of its electricity on the first day and then fully charged it. If it is still the next day, it will be charged in half, and it will be charged twice in total. This can only be counted as one charging cycle, not two. Therefore, it is usually possible to complete a cycle after several charges. The battery capacity is reduced a little every time a charge cycle is completed. However, this power reduction is very small. After a high-quality battery has been charged for many cycles, it still retains 80% of the original capacity. Many lithium-powered products are still used after two or three years. Of course, the life of the lithium battery still needs to be replaced after the end.

The so-called 500 times means that the manufacturer has achieved 625 times of chargeable times at a constant depth of discharge (such as 80%), reaching 500 charge cycles.

(80%*625=500) (ignoring factors such as lithium battery capacity reduction)

Due to the various effects of real life, especially the depth of discharge during charging is not constant, the "500 charging cycle" can only be used as the reference battery life.

Influencing factor