What Are The Common Faults Of Lithium Battery Protection Boards?

A lithium battery protection board is a circuit board designed to safeguard lithium batteries. Its function is to protect the battery from over-discharge, over-charge, and over-current conditions, while also preventing output short circuits. How can a damaged lithium battery protection board be repaired?

If the protection board of a lithium battery fails, you can first attempt to charge it using a charger to see if the protection board can be reactivated. If you cannot fully charge it, the board is likely damaged. This could be due to faulty electronic components or a recent reset. However, if the protection board is indeed damaged, the measured voltage should read 0V. If you have experience with lithium battery protection boards, let's discuss why they might lack charge/discharge protection—hopefully providing some useful insights.

Under what conditions does a lithium battery protection board fail to provide charge/discharge protection?

First, examine the parameters of ternary lithium batteries: lithium and iron have voltage ranges of 2.8V -- 4.25V or 2.5V --3.65V respectively.

1. Possible causes include overcharging, over-discharging, overcurrent, short circuit, or overheating.

2. Use a multimeter to check if the charge/discharge MOSFET is open-circuited.

3. If the protection board has an LED, it will flash for 0.5 seconds as an alarm when charging/discharging fails.

4. If the protection board is connected to a host computer, check the protection status via the host interface.

5. The protection board includes a weak switch; verify if this switch is activated.

In these situations, you can check the following methods to fix the issue:

1. Overcharge, over-discharge, overcurrent, or short-circuit—recycle the charger.

2. Overcurrent—disconnect the load and restore.

What is a lithium battery protection board?

A lithium battery protection board safeguards the charging and discharging of lithium battery packs. After full charge, it ensures the voltage difference between individual cells remains below the set value, enabling uniform charging of all cells within the pack and effectively improving charging efficiency in series charging modes. Simultaneously, it monitors each individual cell within the battery pack for overvoltage, under-voltage, overcurrent, short circuits, and overheating conditions to protect and extend battery lifespan. Under-voltage protection prevents damage to individual cells during discharge by avoiding excessive discharge.

The protective functions of lithium batteries are typically achieved through the coordinated operation of protection circuit boards and current-limiting components such as PTCs. The protection board, composed of electronic circuits, continuously and accurately monitors cell voltage and charge/discharge loop currents within an ambient temperature range of -40 to 85 degrees Celsius, promptly controlling the opening and closing of the current loop. PTCs prevent severe damage to batteries in high-temperature environments.

Common lithium battery protection boards typically include control ICs, MOS switches, resistors, capacitors, and auxiliary components such as fuses, PTCs, NTCs, IDs, and memory chips. The control IC normally keeps the MOS switch conductive, connecting the cell to the external circuit. When cell voltage or circuit current exceeds specified limits, it immediately controls the MOS switch to turn off, safeguarding the cell.

Principle of Lithium Battery Protection Boards:

The need for protection in rechargeable lithium batteries stems from their inherent characteristics. Due to the materials used in lithium batteries, they cannot withstand overcharging, over-discharging, overcurrent, short circuits, or charging/discharging at excessively high temperatures. Therefore, lithium battery packs always incorporate a sophisticated protection board and a current fuse.

The protective functions of lithium batteries are typically achieved through the coordinated operation of the protection circuit board and current-limiting components like PTCs. The protection board, composed of electronic circuits, continuously and accurately monitors cell voltage and charge/discharge loop currents within an ambient temperature range of -40°C to 85°C, promptly controlling the opening or closing of the current circuit. PTCs prevent severe damage to the battery under high-temperature conditions.

Common lithium battery protection boards typically include a control IC, MOS switches, resistors, capacitors, and auxiliary components such as fuses, PTCs, NTCs, IDs, and memory chips. Under normal conditions, the control IC maintains the MOS switches in the on state, connecting the battery cell to the external circuit. When the cell voltage or loop current exceeds specified limits, it immediately controls the MOS switches to turn off, safeguarding the battery cell.