Eternal Inverter 
Classification & principle of batteries
At present, there are lithium batteries, NI-MH batteries, lead-acid batteries, ternary lithium batteries, lithium iron phosphate batteries and so on. The principle of rechargeable battery is based on reversible electrochemical reaction. When charging, electric energy promotes chemical reaction to store energy; When discharging, the chemical reaction is reversed, releasing electric energy.
Take a lithium-ion battery as an example. When charging, lithium ions will escape from the positive electrode and be embedded in the negative electrode, and vice versa when discharging. Hydrogen atoms are absorbed to the negative electrode when the Ni-MH battery is charged, and react reversely when it is discharged. Lead sulfate is converted into lead dioxide and lead when a lead-acid battery is charged, and vice versa when it is discharged.
How many times does the battery charge and discharge?
Generally speaking, the cycle times of lithium batteries are between 300 – 1000 times, NI-MH battery are between 500 – 1000 times, lead-acid batteries are between 200 – 500 times, ternary lithium batteries are between 1500 – 2000 times, and lithium iron phosphate batteries are over 2000 times.
What factors are related to the service life of the battery?
- Charge and discharge times: Most rechargeable batteries have a certain limit on the times of charge and discharge cycles. For example, the performance of lithium-ion batteries will gradually decline after hundreds to thousands of charge and discharge cycles.
- Temperature: The working temperature of the battery will affect its life. High temperature may acceleratethe chemical changes of the internal materials of the battery, while low temperature may reduce the activity and capacity of the battery.
- Charging voltage and current: Too high or too low charging voltage will cause irreversible chemical reaction, damage electrode materials, affect capacity and performance, and thus shorten battery life; If the charging current is too large, the battery will overheat and accelerate aging; if the current is too small, the charging time will be prolongedand the side effects will be increased, which will affect the performance and life of the battery.
- Storage conditions: If the battery is stored for a long time in a fully charged or low-charged state, its performance will be damaged.
- Charging cycle: Each charging and discharging will cause chemical changes inside the battery and material loss of the motor, which will lead to the reduction of capacity, thus shortening the service life.
- Battery type: Different types of batteries (such as lithium-ion batteries, Ni-Cd battery and lead-acid batteries) have different life characteristics.
- Usage mode: High power usage will shorten battery life, while low power usage will prolong battery life.
How to prolong the service life of battery?
- Proper charging and discharging: avoid overcharging or discharging. According to the battery type, know the best charging and discharging range, and try to keep it within the appropriate power range for use.
- Avoid overheating: high temperature will accelerate the aging and capacity attenuation of batteries. Try to avoid exposing the battery to high temperature.
- Avoid overcharging: overcharging will lead to the instability of the internal chemical reaction of the battery, which may shorten the battery life. Don’t let the battery be fully charged for too long.
- Proper storage: batteries that have not been used for a long time should be stored in a dry and cool place, and a proper amount of electricity should be maintained.
- Avoid excessive use: Use the battery reasonably as needed to avoid excessive and frequent charging and discharging.
- Regular maintenance: Regularly clean the contact surface between the battery terminal and the connector to maintain good contact and conductivity.
- Avoid overload: According to the rated capacity and power of the battery, ensure that it does not exceed its bearing range and avoid overload.
- Select the appropriate battery type: select the appropriate battery type according to the use requirements, such as lithium-ion battery, NI-MH battery, etc.
- Avoid mechanical damage
- Follow the manufacturer’s calibration instructions
Optimal theoretical charging curve of battery
The basic requirement of lithium battery charger is specific charging current and voltage, so as to ensure the safe charging of the battery. Other charging auxiliary functions are added to improve the battery life and simplify the operation of the charger, including trickle charging for over discharged batteries, battery voltage detection, input current limitation, turning off the charger after charging is completed, and automatically starting charging after partial battery discharge.
The charging process of lithium-ion batteries can be divided into four stages: trickle charging (low-voltage pre-charging), constant-current charging, constant-voltage charging and charging termination.
The charging method of lithium battery is constant voltage and controlled by IC chip. The typical charging method is: taking ternary lithium battery charging as an example, the voltage of the battery to be charged is first detected. If the voltage is lower than 3V, it must be precharged first, and the charging current is 1/10 of the set current. After the voltage rises to 3V, it enters the standard charging process. The standard charging process is: constant current charging with set current. When the battery voltage rises to 4.20V, it is changed to constant voltage charging, and the charging voltage is kept at 4.20 V.. At this time, the charging current gradually drops, and when the current drops to 1/10 of the set charging current, the charging is over. The following figure shows the charging curve.
The second picture shows that on the basis of today, our measured results are very close to the best state of this theory, which means that our whole charging process is more reasonable and efficient, and it can also prolong the battery life and reduce the aging speed of the battery. Therefore, the scientific charging method and technology can improve the safety of the battery, save energy and reduce the charging cost.
E-HYBRID solar energy technology combined with the application of battery realizes that solar energy is directly output to the load, and the battery is used as a backup, instead of having to be output to the load through the battery. We have two corresponding products for household and industrial and commercial use:
Here are three different scenarios:
As can be seen from this figure: when the sunlight is sufficient, the power will be directly supplied to the load, and the excess electricity will be supplied to the battery for storage; When the sun is not enough, either the solar energy and the battery complement each other, or the solar energy and the mains complement each other, both of which can be fully charged to run the load; When there is no sunlight, the battery or mains supply power directly to the load to run it.