First, what data is used to measure the performance of lithium ion batteries?

1, charge and discharge ratio: the higher the better. C is a special symbol that describes the charge and discharge current of a battery. The 1C discharge represents the current of the battery from full to empty in one hour. If the iPhone 6 battery has a capacity of 1,810 mah, the 1C discharge current of the battery is 1.81 amperes. If the capacity of each battery used by BYD E6 electric vehicle is 200Ah, the discharge current of the battery 1C is 200 amperes. If a battery discharges at a high rate, it usually releases less energy than if it discharges at a low rate.

2, charge and discharge cycles: the more the better. 500 times is the collective value of lithium-ion batteries. Lithium-ion batteries can be charged and discharged between 300 and 3,000 times, depending on the material. The exact meaning of this value may vary slightly for each plant, but can be roughly interpreted as: according to the charge and discharge rate specified by the manufacturer (e.g. 1C discharge, 0.3c charge; From 0% to 100% each time, follow this cycle), after 500 cycles, the initial 80% of the battery capacity remains unchanged. There is too much correlation between charging and discharging times and usage habits. Let's take a few examples. 1. The impact of charge and discharge intensity on the number of cycles: Factory description: each time from 0% charge to 100%, 1C discharge, 0.3c charge, 500 times after the capacity drops to 80%, this is the most serious detection cycle, can also not be so strict. As shown in the figure below, if the power of each cycle is 25%-75%, 1c discharge, 0.3c charge, the capacity drops to 80% after 2000 cycles, and if the power of each cycle is 50%-100%, 1C discharge, 0.3C charge, the capacity drops to 80% after 1800 cycles. 2. Influence of shallow charging and discharge on service life. Factory tip: From 0% charge to 100%, 1c discharge, 0.3c charge after 500 times, capacity attenuation to 80%, this is the most serious detection cycle. It can also be less strict. As can be seen from the following, the power cycle is 25%-75%, 1c discharge, 0.3c charge, and capacity attenuates to 80% after 2000 times. Each power cycle 50%-100%, 1c discharge, 0.3 charge, 1800 times after capacity attenuation to more than 80%. It can be seen from the two examples that the smaller the charge-discharge ratio is, the more beneficial it is to improve the service life; Shallow charge and discharge is also beneficial to improve service life
3, internal resistance: the smaller the better. This parameter varies with load weight, temperature, and other factors. As battery life shortens, internal resistance increases. The smaller the internal resistance, the higher the charge and discharge rate. The internal resistance of the ordinary 18650 battery is about 50m, and that of the power 18650 battery is about 15m. If you want to know how big the internal resistance is, you need to use special equipment to measure it. In general, multimeters cannot
4, battery consistency the same material and process of the battery capacity, internal resistance and charge-discharge curve consistency of the higher the better. The larger the size of the battery pack, the more consistent the battery pack.