1. Overcharge protection

Overcharge protection means that when our battery is charged to a certain value, the protection board will stop the charger to continue charging the battery. The BMS protection board of the lithium battery is controlled by the charging MOS tube, and the charging MOS tube is controlled For the protection chip, when the protection chip detects that the battery is full, it will give a signal to turn off the MOS tube at this time, so as to achieve the effect of stopping charging (protection).

2. Over-discharge protection

Literally, it is easy to understand. The principle of over-discharge protection is actually the same as that of overcharge protection, but the protection voltage is low voltage. When the protection chip detects that the battery voltage is too low, it will also discharge the MOS. Control a shutdown signal to stop battery discharge, this process is just the opposite of the action of overcharge protection.

3. Short circuit protection

Short circuit means to connect the output terminals of the battery together. Short circuit is a very dangerous phenomenon. Many times the battery smoke and explosion are caused by short circuit. If the capacity of the battery cell is relatively large, the discharge rate is also relatively large. , a very thick copper wire will burn in an instant. One can imagine how dangerous it is. The principle of short circuit protection is that when the chip detects that the user connects P+P- or accidentally connected, it will instantly disconnect the battery. The output terminal, so as to achieve the effect of protection.

4. Overcurrent protection

In fact, the overcurrent protection is similar to the short circuit protection. They both trigger the protection function by detecting the current. The overcurrent protection means that when our discharge current or charging current reaches our designed parameters, it will automatically disconnect the charging MOS. Tube or discharge MOS tube, because the current capacity of the MOS tube is limited, the current carried by different types of MOS tubes is different. If there is no over-current protection, once the carrying current of the MOS tube is exceeded, the MOS will be broken down immediately.

5. Over temperature protection

Over-temperature protection uses a thermistor to detect the temperature on the battery core. When the temperature is too high, the protection chip will also disconnect the MOS tube. At this time, the main board has no output. When the temperature returns to normal temperature, the MOS The tube will open automatically and the motherboard will work normally.

6. Balance function

Everyone knows that when our batteries are used in series, if the voltage of a certain battery is too low or too high, it will affect the performance of the entire battery pack, then the balance will play a role at this time, and the balance function will make The voltage of each battery is consistent, so as to achieve better use effect.

In fact, the protective plate is equivalent to the human brain. For example, when a person is full, if you continue to force him to eat, he will definitely die in the end. If the brain knows that it is full, it will not eat again. Equivalent to the overcharge function, the principle of overdischarge and starvation is the same. I believe everyone can understand this, so when we use lithium batteries, we must add a protection board, which not only protects our personal safety. , more family security as a guarantee. In the next issue, I will teach you how to choose a lithium battery that suits you.