The functions of PCM (protection circuit module) for lithium batteries
Published time: 2017-9-14 3:44:24, Publisher:
Because of the chemical activity, structure and other reasons, lithium batteries need to have a protective system, if there is no protection system, lithium battery life will be greatly affected, and there may be a risk of explosion or burning in serious cases. Lithium batteries without PCM are forbidden to use. Lithium battery should avoid deep charge and discharge, otherwise it will affect the battery life.
PCM of lithium battery usually includes control IC, MOS tube, resistor, capacitor and auxiliary components FUSE, PTC, NTC, ID, memory unit etc. Among them, control IC is the core of the protection chip, MOS tube in the protection board circuit play the role of switch. IC control the MOS tube switch in all normal circumstances, to ensure that the batteries and external circuit conduction, and when the battery voltage or loop current exceeds the specified value, it immediately control the MOS switch off, to protect the safety of lithium batteries.
The function of PCM is to protect the rechargeable batteries, maintain the safety and stability of the battery charge and discharge process, play an important role of the entire battery circuit system, the functions are as follows:
1. Over-charge protection
When charging the battery, the voltage reaches the maximum voltage of lithium batteries (4.2V), PCM will control the overcharge of the MOS tube into the off state, stop charging, thus preventing the battery overcharge.
2. Over-discharge protection
When the battery is end of discharge coming soon, the voltage reaches the minimum value (usually 3V, there are some differences in different manufacturers), the PCM will control the over-discharge of the MOS tube into the off state, to prohibit its discharge, so as to prevent its over-discharge.
3. Over-current protection
Over-current protection function is in the consumption of high current to stop the discharge of the load, the purpose of this function is to protect the battery and MOS tube to ensure that the battery in the working state of the security. After over-current detection, the battery will return to normal after disengaging from the load, and can be recharged or discharged.
4. Short-circuit protection.
When the lithium battery accidentally short circuit, the PCM will automatically shut down in a few milliseconds, will not electrify, then the positive and negative encounter is also nothing, the formation of a short circuit protection will not cause the explosion occurred.
