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Lithium battery protection board PCBA repair method

2021-04-19

Lithium battery protection board PCBA repair method

12v lithium battery protection board PCBA repair

12v lithium battery is a voltage close to 12v obtained by connecting multiple 3.7v lithium batteries in series, and we must use the 12v lithium battery protection board PCBA, which can protect the series lithium battery pack.

When the lithium battery is fully charged, it can play the role of equalizing the voltage difference of each single lithium battery, effectively solving the loopholes in the series circuit. So how to repair the protection board of the electric fish special 12v lithium battery pack? The following editor lists some common problems of the protection board for analysis and maintenance.

1. No voltage or abnormal voltage

If there is no voltage or abnormal voltage, we should adjust the multimeter to the DC 20V position, and then use the red meter pen to touch the positive pole of the lithium battery cell, and the black meter pen touch the negative pole of the cell. If the multimeter shows that there is no voltage or the voltage is very low , It proves that the battery is damaged.

Pay attention to check whether the positive and negative poles of the protection board are reversed. If they are reversed, the charger is equivalent to forced over-discharge when charging the lithium battery pack.

2. No overcurrent protection

There is no over-current protection, etc., first check whether the circuit of the over-current detection pin is defective, and replace the protection IC if there is any.

3. there is no resistance or the resistance is too large

It is necessary to look for the cause from the identification circuit of the resistance pad, check whether the identification resistance is disconnected, whether the resistance is wrongly attached, whether there is a short circuit or an open circuit, etc.

4. can not charge

Use the multimeter switch to select the 20v gear, and then use the red meter pen to touch the positive electrode of the cell or the protection board. If the multimeter shows voltage, we will analyze it according to the following conditions: Is there an output voltage? Is the cell voltage normal Happening.

If the above voltage is not normal, we can basically judge that the protection IC or MOS tube has been damaged. At this time, it is enough to replace these two components.

5. No internal resistance or excessive internal resistance

1. If there is no internal resistance, you need to check whether the pins of the MOS tube are damaged. If so, just replace the MOS tube.

2. If the internal resistance is too large, then use a probe to contact the electric fish lithium battery protection board PCBAPCBA to detect whether there is poor contact or excessive oxidation. It is also necessary to check whether there are more nickel sheets on the battery core. If the number of nickel sheets on the battery core is too large, it will cause excessive internal resistance.

The PCBA repair method of the electric fish lithium battery protection board used above is basically through comparison, visual inspection, voltage measurement, and on-off test. As long as you master these methods, I believe you can also be skilled in repairing electric fish Lithium battery pack protection board.

Lithium battery protection board PCBA repair method (MOS tube burned out)

MOS tube burned out during the discharging process of the battery protection board:

There is a short-circuit phenomenon in the welding process, the MOS tube is not fully opened during the discharge process, and it is in the closed or half-open state. The internal resistance of the PCBA becomes larger, and the large current discharge for a long time will cause heat and burn out.

There is static residue in the production and assembly process, or there is an external abnormal current/high voltage during the charging and discharging process, which causes the MOS tube to be damaged and burnt.


  Approach:

It is recommended to solder the B4-wire first (because the risk of short-circuiting R19 near the B2 string is high) and then solder the B2 string during the stringing process, so as to avoid the defects caused by the short-circuit of B2 and B4.

  Protective measures:

Do a good job of ESD protection in all links of the production process.

During the welding process, especially the live posts, prevent touching the components or lines.

It is recommended to solder the B4 wire first and then the B2 wire in the process of soldering serial wires.

Lithium battery protection board PCBA repair method (without charge and discharge protection)

What are the situations where the lithium battery protection board PCBA has no charge and discharge protection?

First look at the ternary parameters: the conventional is 2.8-4.25, and the iron-lithium is 2.5-3.65V.

1. It may be overcharge, overdischarge, overcurrent, short circuit, and overtemperature.

2. Use a multimeter to check whether the charging and discharging MOS tube is turned on.

3. If the lithium battery protection board PCBA is equipped with an LED, and it cannot be charged or discharged, the LED flashes for 0.5 seconds to give an alarm.

4. If the lithium battery protection board PCBA is with a host computer, you can connect the host computer to view the protection status.

5. The lithium battery protection board PCBA has a weak point switch. Please check whether the weak point switch is turned on.