How to measure the performance of lithium batteries

1. Charge and discharge rate: the higher the better, C is a special symbol to describe the size of battery charge and discharge current. 1C discharge means the amount of current required to discharge the battery from full to empty within 1 hour. The battery capacity of iPhone6 u200bu200bis 1810mAH, so the 1C discharge current of this battery is 1.81 amps; each battery used in BYD e6 electric car has a capacity of 200 AH, then the 1C discharge current of this battery is 200 amps. If a battery is discharged at a high rate, it usually emits less energy than a low rate. Second, the number of charge and discharge cycles: the more the better, 500 times is a common value for lithium batteries. The number of charge and discharge cycles for lithium batteries made of different materials ranges from 300 to 3000 times. The detailed meaning of this value may be slightly different for each factory. It can be roughly understood as: according to the charge and discharge rate specified by the manufacturer (for example, 1C discharge, 0.3C charge; charge and discharge from 0% to 100% each time, follow this cycle) , After 500 cycles, the battery capacity is still 80% of the original. The relationship between the number of charge and discharge and usage habits is too great, let's give a few examples. 1. The influence of charge and discharge intensity on the number of cycles is marked by the factory: each time from 0% to 100%, 1C discharge, 0.3C charge, the capacity decays to 80% after 500 times. This is the most stringent detection cycle. It doesn’t need to be so strict. Look at the following. If each cycle of power is 25%-75%, 1C discharge, 0.3C charge, the capacity decays to 80% after 2000 times. If each cycle of power is 50%-100%, 1C discharge, 0.3 charge, capacity decays to 80% after 1800 times 2. Shallow charge and shallow discharge impact on lifespan Factory mark: each time from 0% to 100%, 1C discharge, 0.3C charge, capacity decays after 500 times 80% is the most stringent detection cycle. It can also be less stringent. See below, the power cycle is 25%-75%, 1C discharge, 0.3C charge. After 2000 times, the capacity decays to 80% every time The power cycle is 50%-100%, 1C discharge, 0.3 charge, after 1800 times, the capacity decreases to more than 80%. Two examples can be seen that the smaller the charge and discharge rate, the more conducive to the life extension; shallow charge and shallow discharge are also Conducive to life extension. 3. Internal resistance: The smaller the better. This parameter changes with the load, temperature and other factors at any time. As the battery life decreases, the internal resistance gradually increases. The lower the internal resistance, the more high-rate the battery can be charged and discharged. The internal resistance of a typical 18650 battery is about 50m, and that of a power-type 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. Generally, a multimeter will not work. Fourth, the consistency of the battery The higher the consistency of the battery processed with the same material and the same technology in the capacity, internal resistance, and charge-discharge curve, the better. Whether batteries can be assembled into battery packs on a large scale is very important. The larger the battery pack size, the higher the consistency requirements. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: Is the 18650 lithium battery durable?