What to pay attention to when choosing lithium iron phosphate battery protection board

For the life of the lithium iron phosphate battery pack, it is recommended that the charging voltage of the lithium iron phosphate battery should not exceed 3.6v at any time, which means that the protection action voltage of the maintenance board should not be higher than 3.6v, and the balanced voltage advocates 3.4v-3.5v (each cell 3.4v has been charged to more than 99% of the power, which refers to the stop condition, the voltage will increase when charging with high current). The discharge protection voltage of lithium iron phosphate battery is generally 2.5v or more (above 2v is not a big problem, generally it is rarely used to completely run out of electricity, so this requirement is not high). The lithium iron phosphate battery charger advocates that the highest voltage (the highest constant voltage charging mode in the final step of charging) is 3.5*the number of strings, for example, the number of strings is about 56v. Normally charging can cut off the charge at an average of 3.4v per cell (it is completely overcharged), so that the life of the lithium iron phosphate battery is guaranteed, but because the protection board has not yet started to be balanced, if the battery cell has a large self-discharge, it will go by over time. This is reflected in the gradual decrease in the capacity of the entire group. Therefore, it is also necessary to charge each cell of lithium iron phosphate battery to 3.5v-3.6v on time (for example, every week) and hold for a few hours (only need to be greater than the equilibrium starting voltage on average). The greater the self-discharge, the greater the equilibrium demand. Cells with long and excessive self-discharge are now difficult to balance and need to be removed. So when choosing the protection board, try to choose 3.6v overvoltage maintenance, and 3.5v to start balanced. (Most of the shopping malls are over-voltage maintenance above 3.8v, and balance is started above 3.6v). In fact, choosing a suitable balanced starting voltage is more important than maintaining the voltage. Because the maximum voltage can be restricted by adjusting the maximum voltage of the charger (that is, the maintenance board usually has no time for high-voltage maintenance), but if the balanced voltage is high, the lithium iron phosphate battery pack has no time. Equalization (unless the charging voltage is greater than the equalization voltage, but this affects the life of the lithium iron phosphate battery), the cell will slowly decrease due to the self-discharge capacity (the ideal cell with a self-discharge of 0 does not exist). The protection board is capable of continuous discharge current. This is the most difficult thing to talk about. Because it is meaningless to say that the maintenance board is capable of limiting the current. For example, if you let a 75nf75 tube continue to pass 50a current (at this time, the heating power is about 30w, and at least two 60w in series with the same port board), it is no problem to have a heat sink to satisfy the heat dissipation. Able to insist on not burning tubes at 50a or even higher. But you can't say that this protection board can last 50a current. Because most of our protection boards are placed in the lithium iron phosphate battery box and the lithium iron phosphate battery is very close, or even close. Therefore, such a high temperature will heat the lithium iron phosphate battery to heat up. The problem is that high temperature is the mortal enemy of the lithium iron phosphate battery. Therefore, the operating environment of the protection board determines how to choose the current limit size (not the current ability of the protection board itself). If the protection board is taken out of the lithium iron phosphate battery box, then almost any protection board with a heat sink can handle 50a continuous current or even higher (at this time, only the protection board should be considered, and there is no need to worry about the temperature rise. To harm). Let's talk about our common environment, which is in the same confined space as the lithium iron phosphate battery. At this time, the maximum heating power of the protection board is best controlled below 10w (if the small protection board needs 5w or less, the large-volume protection board can be more than 10w, due to its good heat dissipation, the temperature will not be too high). As for how much suitable, it is recommended to continue The maximum temperature of the entire board does not exceed 60 degrees when current is applied (50 degrees is the best). Theoretically, the lower the temperature of the protection board, the better, and the less it will affect the cells. Disclaimer: Some pictures and content of the articles published on this site are from the Internet. If there is any infringement, please contact to delete.