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Function analysis of lithium ion battery protection board

Time:2020-12-17 Views:295

  Li-ion battery protection board is a series of lithium-ion battery charge and discharge protection. After charging, it can ensure that the voltage difference between the individual cells is less than the set value (generally ±20mV), so as to realize the uniform charging of the individual cells and effectively improve the charging effect in the series charging mode. At the same time, it detects the overvoltage, undervoltage, overcurrent, short circuit, and overtemperature status of each single battery to protect and extend battery life. Low voltage protection can prevent the battery from being damaged due to over-discharge during the discharge process.

Function analysis of lithium ion battery protection board(图1)

  Voltage protection

  1. Voltage protection: overcharge and overdischarge, depending on the battery material.

  Overcharge protection, our previous single battery protection voltage will be higher than the battery charging voltage of 50~150mV. But the power lithium battery is different. If you want to extend battery life, your protection voltage should be the charging voltage of the battery, or even lower. For example, for ternary battery, you can choose 4.18v~4.25v; for lithium iron battery, you can choose 3.65-3.9. Because it is a multi-series, the life capacity of the entire battery pack depends on the minimum capacity of the battery. Small capacity always works under high current and high voltage, so the attenuation speed is accelerated. On the other hand, a large-capacity battery has a much slower decay rate every time it is charged lightly. In order to make small-capacity batteries can be lightly charged, the overcharge protection voltage point should not be selected too high. This protection delay can reach 1S to prevent impulse impact protection.

  Over-discharge protection is also related to battery materials. For example, ternary batteries generally use 2.8v~3.0v; lithium iron phosphate batteries generally use 2.3-2.5v. Try to make it a little higher than the overvoltage of its single battery. Because, among the batteries produced in China, the battery voltage is lower than 3.3v (ternary), 2.8v (lithium iron), and the discharge characteristics of each battery are completely different. Therefore, the battery is protected in advance to make the battery's service life very long. Good protection.

  The general point is to try to make each battery work under a light charge, which must contribute to the life of the battery.

  Over-discharge protection delay time, it should be changed according to different loads, such as electric tools, the starting current is generally greater than 10C, so it will pull the battery voltage to the over-discharge voltage point for protection in a short time. You cannot make the battery work. This is worth noting.

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