There are several important indicators to measure the battery performance:
I.charge discharge ratio:higher is better
"C"is a special symbol to describe the charging and discharging current of battery.1C discharge represents the current to discharge the battery from full charge to empty in one hour.If the capacity of iPhone 6 battery is 1810mah,the 1C discharge current of this battery is 1.81a;if the capacity of each battery used in BYD E6 electric vehicle is 200ah,the 1C discharge current of this battery is 200A.If a battery is discharged at a high rate,it usually emits less energy than a low rate.
II.Cycle times of charge and discharge:more is better
500 times is the common value of lithium battery.The charge and discharge times of lithium battery made of different materials vary from 300 to 3000 times.The specific meaning of this value may be slightly different in each factory,which can be roughly understood as:according to the manufacturer's specified charge discharge ratio(such as 1C discharge,0.3C charge;each time from 0%charge to 100%,according to this cycle),after 500 cycles,the battery capacity remains 80%of the original.The relationship between charge and discharge times and usage habits is too large.Let's give a few examples.
1.Influence of charge and discharge intensity on cycle times
Factory mark:from 0%charge to 100%,1c charge to 0.3C charge each time,the capacity will decline to 80%after 500 times.This is the most severe test cycle,or not so strict.See below
If the power cycle is 25%-75%each time,1c discharge,0.3C charge,the capacity will decline to 80%after 2000 times
If the power cycle is 50%-100%each time,1c discharge,0.3 charge,the capacity will decay to 80%after 1800 times
2.Influence of shallow filling and shallow drainage on service life
Factory mark:from 0%charge to 100%,1c charge to 0.3C charge each time,the capacity will decline to 80%after 500 times,which is the most severe test cycle,or not so strict.See below
Each power cycle is 25%-75%,1c discharge,0.3C charge,and capacity decays to 80%after 2000 times
Each power cycle is 50%-100%,1c discharge,0.3 charge,1800 times later,the capacity will decline to 80%
From the above two examples,it can be seen that the smaller the ratio of charge and discharge is,the better the service life will be;the shallower the charge and discharge is,the better the service life will be.
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 increases gradually.The smaller the internal resistance,the higher the rate of charge and discharge.The internal resistance of 18650 battery is about 50 mΩ,and that of 18650 battery is about 15 mΩ.If you want to know how big the internal resistance is,you need to use special equipment to measure it.
The higher the consistency of battery capacity,internal resistance and charge discharge curve is,the better it is.It is very important that the battery can form a large-scale battery pack.The larger the battery pack size,the higher the consistency requirements.
Application and technical points of Li-ion battery in energy storage scenarioPrevious