Common faults of lithium battery protection board

We all know that there is a protective board in lithium batteries that effectively protects them when they encounter problems. However, our lithium battery protection board can also malfunction. Today, the editor has compiled some common problems related to lithium battery protection boards to share with you.

1、 Low voltage of lithium battery, unable to carry load

Firstly, we need to rule out battery cell defects. If our battery cells are defective, we should check the self consumption of the lithium battery protection board to see if it is due to excessive self consumption of the protection board causing low battery cell voltage. If our battery cell voltage is normal, it may be because the entire circuit of the lithium battery protection board is not connected.

           2、 Lithium battery protection board short circuit without protection

We can first check where the problem is, such as the VM terminal resistor, IC, and MOS malfunction, both of which are normal defects, or short circuit malfunctions caused by poor IC and MOS equipment.

3、 Lithium battery protection board short circuit protection without self recovery

This situation may be due to the instrument setting having a short short-circuit recovery time, or the load not being removed during short-circuit inspection. We can use a multimeter voltage range to short-circuit the probe without removing it from the inspection end. Or if there is leakage between P+and P -, if it is not the previous problem, it is possible that the IC has been broken down. We can check the resistance between the pins of the IC.

4、 Lithium battery protection board has high internal resistance

Because the internal resistance of MOS is relatively stable, if there is a situation of high internal resistance, we first need to check components such as FUSE or PTC, which have relatively simple internal resistance changes.

If our FUSE or PTC resistance is normal, it may be due to micro breakage in the via, resulting in a high resistance. Another possibility is whether the MOS has malfunctioned. First, check if there are any issues with the solder joint, the thickness of the second signboard, and whether it has been simply bent. Finally, place the MOS tube under a microscope to observe if it has ruptured; It is still necessary to use a multimeter to check the resistance of MOS pins and whether they have been broken down.

5、 The ID of the lithium battery protection board is abnormal

Because our ID resistor itself may experience virtual soldering, cracking, or malfunction due to poor resistance material: we can solder the two ends of the resistor from scratch. If the ID is normal after re soldering, it means that the resistor has virtual soldering. If it cracks, the resistor will crack from the middle after re soldering. A multimeter can be used to check whether the ID via is conductive at both ends of the via. Finally, if there is a problem with our internal circuit, we can scrape off the solder mask to see if there is any disconnection or short circuit in the internal circuit