Views: 2 Author: Site Editor Publish Time: 2024-04-16 Origin: Site
The charging and discharging characteristics and service life of lithium iron phosphate battery packs. Based on the discharge curve of the lithium iron phosphate battery pack, it is possible to determine whether the battery's performance is stable and the maximum current allowed for stable operation. Among them, many factors also affect the service life of lithium battery packs. So, what is the service life of lithium iron phosphate battery packs? What are the characteristics of discharge characteristics?
Lithium battery packs have a high energy density and an average output voltage. Low self discharge, below 10% per month. There is no memory effect. The working temperature range is wide from -20 ℃ to 60 ℃. Superior cycling performance, fast charging and discharging, charging efficiency up to 100%, and high output power. Long service life, known as green batteries. The charging process of lithium iron phosphate batteries is divided into two stages: constant current fast charging stage and constant voltage current decreasing stage.
In the constant current fast charging stage, the battery voltage gradually increases to the standard voltage of the battery, and then enters the constant voltage stage under the control chip. The voltage no longer rises to ensure that overcharging will not occur, and the current gradually decreases to 0 as the battery level increases, ultimately completing the charging process. The power statistics chip can sample and calculate the battery's power by recording the discharge curve. After multiple uses, the discharge curve of lithium-ion batteries will change. Although lithium-ion batteries do not have memory effects, improper charging can seriously affect battery performance.
Excessive discharge of lithium iron phosphate batteries leads to the collapse of the negative carbon layer structure, which can cause lithium ions to be unable to be inserted during the charging process; Overcharging causes excessive lithium ions to embed into the negative electrode carbon structure, causing some of the lithium ions to no longer be released. The discharge time of lithium batteries is related to the battery capacity and discharge current. When the battery is discharged=battery capacity/discharge current. The discharge current of lithium batteries should not exceed three times the battery capacity, otherwise it will cause damage to the battery.
1. Charge according to standard time and procedure, even for the first three times;
2. When the battery level is too low, it is advisable to start charging as soon as possible;
3. The activation of lithium iron phosphate batteries does not require special methods, and lithium batteries will naturally activate during normal use. If you insist on using the popular "first three 12 hour long charging activation" method, it will not actually be effective.
Taking into account various factors, the usage characteristics of iron lithium battery packs can be roughly described as follows: relatively large size, poor low-temperature performance, and the ability to maintain a relatively gentle decay rate during the lifespan, which is generally acceptable for about 8 years; But if used in the south. The lifespan of lithium iron phosphate batteries is even longer than 8 years.
The lifespan of lithium iron phosphate battery packs is 4-5 times longer than that of lead-acid batteries, and it is not a problem to reach a lifespan of 5 years for lead-acid batteries with higher technological content nowadays. Lithium batteries, due to the structural collapse of the negative electrode material graphite, will be scrapped even if left unused for five years.
I believe the vast majority of consumers have heard that the lifespan of a lithium battery pack is "500 times", with 500 charges and discharges. Beyond this number, the battery will "end its life". Many friends, in order to extend the lifespan of the battery, charge it every time the battery is completely depleted. Does this really have an effect on extending the lifespan of lithium batteries? The answer is negative. The lifespan of a lithium battery is 500 cycles, which refers not to the number of charges, but to one cycle of charging and discharging.
The lifespan of lithium iron phosphate battery packs is generally 300-500 charging cycles. Assuming a complete discharge provides Q of electricity, without considering the decrease in electricity after each charging cycle, a lithium battery can provide or supplement a total of 300Q-500Q of electricity during its lifespan. From this, we know that if you charge with 1/2 each time, you can charge 600-1000 times; If 1/3 is used each time to charge, it can be charged 900-1500 times. Similarly, if charging randomly, the number of times is uncertain. In short, no matter how it is charged, the total amount of electricity replenished from 300Q to 500Q is constant.
So, we can also understand it this way: the lifespan of a lithium battery pack is related to the total charging capacity of the battery, and is not related to the number of charges. The impact of deep discharge and shallow discharge on the lifespan of lithium batteries is not significantly different. In fact, shallow discharge and shallow charging are more beneficial for lithium iron phosphate batteries.
1. Currently, the use of power batteries is achieved by grouping batteries in series or parallel with individual batteries. However, lithium battery packs require high consistency among individual batteries due to their characteristics. As long as there is one battery in a group that is different from other batteries, the overall effect will be greatly reduced. So, users of lithium batteries must pay attention to taking care of the battery during use, and also avoid overcharging and discharging;
2. When it is found that the battery has broken after a period of use and needs to be soldered again, special attention should be paid to not touching the positive and negative poles of the battery at the same time with the soldering iron. In addition, during the transportation of batteries, the best method is to separately put a self sealing bag on each lithium battery and place it in an explosion-proof box to prevent short circuits or skin damage caused by bumps and collisions during transportation, which may cause the positive and negative poles of a certain battery to collide with other conductive substances and short circuits;
3. Lithium iron phosphate batteries should be stored in a cool and shady environment. When storing batteries for a long time, it is best to place them in a sealed bag or sealed explosive box. It is recommended to have an ambient temperature of 10-25 ° C, dry, and free of corrosive gases;
4. Do not mix new and old lithium batteries or different models of lithium battery chargers.
The above is an explanation of the charging and discharging characteristics and service life of lithium iron phosphate battery packs. Due to the internal structure of lithium iron phosphate batteries, lithium ions cannot all move towards the positive electrode during discharge. It is necessary to keep a portion of lithium ions at the negative electrode to ensure that lithium ions can be smoothly embedded in the channel during the next charging. Otherwise, the lifespan of lithium batteries will be correspondingly shortened.
