1. Charge and discharge rate: the higher the better
"C" is a special symbol to describe the charge and discharge current of a 12v lithium battery. 1C discharge means the amount of current required to discharge the battery from full to empty within 1 hour. The battery capacity of the iPhone 6 is 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 releases less energy than a low rate.
2. Number of charges and discharge cycles: the more the better
500 times is a common value for lithium batteries, and the charge and discharge times of 12v lithium batteries made of different materials range from 300-3000 times. The specific 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 (such as 1C discharge, 0.3C charge; each time from 0% to 100%, the cycle is repeated), After 500 cycles, the battery capacity is still 80% of the original. The relationship between the number of charges 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
Factory mark: each time charge and discharge from 0% to 100%, 1C discharge, 0.3C charge, the capacity will decrease to 80% after 500 times. This is the most stringent test cycle, and it can be less stringent. See below
If the power cycle is 25%-75% each time, 1C discharge, 0.3C charge, the capacity will decrease to 80% after 2000 times
If the power cycle is between 50%-100%, 1C discharge, 0.3 charges, the capacity will decrease to 80% after 1800 times
2. The impact of shallow charge and shallow discharge on life
Factory mark: each time charge and discharge from 0% to 100%, 1C discharge, 0.3C charge, the capacity decreases to 80% after 500 times. This is the most stringent test cycle, or it can be less stringent. See below
The power cycle is 25%-75% each time, 1C discharge, 0.3C charge, after 2000 times, the capacity decays to 80%
Each cycle of power is between 50%-100%, 1C discharge, 0.3 charge, capacity decays to 80% after 1800 times
From the above two examples, it can be seen that the smaller the charging and discharging rate, the more conducive to the increase of life; shallow charge and shallow discharge are also conducive to life.
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 of the battery, the more high-rate charging and discharging is possible. The internal resistance of an ordinary 18650 battery is about 50mΩ, and that of a power-type 18650 battery is about 15mΩ. If you want to know how big the internal resistance is, you need to use a special device to measure it, not a normal multimeter.
4. battery consistency
The higher the consistency of the capacity, internal resistance, and charge-discharge curve of 12v lithium batteries produced with the same material and the same process, the better. Whether batteries can be assembled into battery packs on a large scale is very critical. The larger the battery pack size, the higher the consistency requirements.
