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　　12v lithium battery is a voltage close to 12v obtained by connecting multiple 3.7v lithium batteries in series, and we need to use a 12v lithium battery protection board for series series lithium batteries, which can protect series series lithium battery packs. When the lithium battery is fully charged, it can play the role of equalizing the voltage difference of each single lithium battery, and solve the loophole of the series circuit. So how to repair when the special 12v lithium battery pack protection board for electric fish is abnormal? 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 gear, and then use the red meter pen to contact the positive cell of the lithium battery, and the black meter pen to contact the negative cell. If the multimeter shows no voltage or the voltage is very low , it proves that the battery is damaged. Pay attention to check whether the positive and negative of the protection board are reversed. If the connection is reversed, the charger is equivalent to forced over-discharge when charging the lithium battery pack.

2. No overcurrent protection

If there is no overcurrent protection, first check whether there is any problem with the circuit of the overcurrent detection pin, and if so, replace the protection IC.

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

It is necessary to find the reason from the identification circuit of the resistance pad, and check whether the identification resistance is unsoldered, whether the resistance is wrongly attached, whether there is a short circuit or an open circuit, etc.

Four, can not charge the electricity

Use the multimeter switch to select the 20v gear, and then use the red meter pen to touch the positive or protective plate of the cell. If the multimeter shows voltage, we must analyze it according to the following conditions: Is there an output voltage? Whether the cell voltage is normal. If the above voltages are not normal, we can basically judge that the protection IC or the MOS tube has been damaged. At this time, it is necessary to replace these two components.

Fives. There is no internal resistance or the internal resistance is too large

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

2. If the internal resistance is too large, then use a probe to contact the lithium battery protection board of the electric fish to detect whether there is a contact problem 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 also cause the phenomenon of excessive internal resistance.

The maintenance methods of the lithium battery protection board used in the above are basically four types of 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 lithium battery special for electric fish. Battery pack protection plate.

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

The reasons for the burnout of the MOS tube during the discharge process of the battery protection board:

There is a short circuit phenomenon in the process. During the discharge process, the MOS tube is not fully opened, and it is in a closed or half-open state. The internal resistance of the PCBA becomes larger, and the high current discharges for a long time, and the heat burns out and burns.

Static electricity remains in the production and assembly process, or there is an external abnormal current/high voltage charging and discharging process during the charging and discharging process, which causes the MOS tube to be damaged and burned.

Approach:

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

Protective measures:

Do a good job of ESD protection in all aspects of the production process,

Processes, especially live posts, prevent touching components or lines,

It is recommended to solder B4 first and then B2 during the stringing process.

Toutiao is a good project for starting a business with a small budget of 10,000 yuan, and training in the assembly and maintenance of lithium batteries for electric vehicles. Learn more about the basic knowledge training of lithium battery assembly and maintenance by clicking the blue font link

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

Under what circumstances does the lithium battery protection board have no charge and discharge protection?

First check the ternary parameters: conventional is 2.8 ~ 4.25, iron lithium is 2.5 ~ 3.65V

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

2. Use a multimeter to test whether the charge and discharge MOS tube is turned on

3. If the lithium battery protection board is equipped with LED, the LED flashes for 0.5 seconds if it cannot be charged or discharged

4. If the lithium battery protection board is equipped with a host computer, you can connect it to the host computer to check the protection status

5. The lithium battery protection board has a weak switch, please check whether the weak switch is turned on

In these cases, you can check the following methods for repair:

1. Overcharge, over-discharge, over-current, short-circuit insertion into the charger to restore

2. Overcurrent disconnect load recovery