Test method for lithium ion battery protection plate

The lithium battery protective plate profile

Lithium battery protection board is the charge and discharge protection of lithium battery pack in series. Make ensure that voltage difference of each monomer battery is less than the set value (plus or minus 20MV) commonly, realize each battery monomer battery charge balance, and effectively improve the charging effect of serial charging mode ; At the same time, detect the states  of overvoltage, under-voltage, over current, short circuit, over temperature of every single battery in the battery pack, protect and extend the service life of the battery; Under-voltage protection makes every single battery in discharge to avoid being damaged because of over discharge.

Lithium electricity The working principle of pool protection plate

The working principle of protection plate graph:

As shown in figure, the IC from batteries, power supply, voltage in 2V to 5V can ensure reliable work.

1, the overcharge protection and overcharge protection

When the battery is charged so that the voltage exceeds the set value VC (4.25-4.35v, the specific overcharge protection voltage depends on IC), VD1 flips to make Cout low level, T1 cut-off, and charging stops. When the battery voltage falls back to VCR (3.8-4.1v, the specific overcharge protection recovery voltage depends on IC), Cout becomes a high level, T1 conduction charging continues, and VCR must be less than a fixed value of VC to prevent frequent jump.

When the battery is charging voltage more than the set value VC (4.25-4.35 V, voltage depends on the specific overcharge protection IC) after VD1 flip make Cout a low level, T1 cut-off, stop charging. Fell when the battery voltage to VCR (3.8-4.1 V, recovery voltage depends on the specific overcharge protection IC), Cout is a high level, T1 conduction charging continue, VCR VC must be smaller than a fixed value, in order to prevent frequent jump.

2, Put the protection and over discharge protection

When the battery voltage drops to set data due to discharge of VD (2.3-2.5 V, voltage depends on the specific overcharge protection IC), VD2, with short time delay, make it become a low level, Dout T2 cutoff, discharge to stop, when the battery is in charge, internal or reverse the door was again and make the T2 conduction to prepare for the next discharge.

3, over current, short circuit protection

When the circuit to charge more than set value or is short circuit loop current, short circuit detecting circuit, the MOS tube shut off, current cut-off.

Lithium battery protection board common faults

1, no display, low output voltage, with no load

2, don't charge

3, no internal resistance and resistance

4, without resistance

5, large flow

6, not decoding

Lithium battery protection board quality detection

A, to ensure that the sampling line (line) connection is correct.

7 series battery 8 pin line do a sample

B - line connect battery cathode

B1 line 1 series of battery positive electrode

B2 line 2 series of battery positive electrode

B3 line 3 series of battery positive electrode

B4 line 4 series of battery positive electrode

B5 line 5 series of battery positive electrode

B6 line 6 series of battery positive electrode

B7 line 7 series of battery positive electrode

PS: 7 battery packs the positive pole of the seventh battery pack is also the total positive pole, and the same applies to any battery pack.

Second, the battery discharge line determined by multimeter wiring is correct

1, through the use of multimeter black pens and pin B - line terminal and multimeter red pens and pressure letter B1 line terminal, 1 series of battery voltage is 3.584 V.

2, by using a multimeter black pens and pin letter B2 B1 line terminal and multimeter red pens and pressure line terminal, 2 series of battery voltage is 3.584 V.

3, through this method, it is concluded that:

1 series battery voltage: 3.584 V

2 series of battery voltage: 3.584 V

3 series battery voltage: 3.585 V

4 series of battery voltage: 3.585 V

5 series of battery voltage: 3.583 V

6 series battery voltage: 3.583 V

7 series battery voltage: 3.584 V

The 7 series voltage is 3.58 V, row line connection is correct, and the battery voltage is lower than 0.002 V, the battery good consistency.PS: Battery voltage should be: lithium ternary voltage in 3.0-4.2v; lithium iron phosphate voltage is about 2.0-3.6v; lithium titanate is about 1.5-2.75v. If any series of voltages differ by more than 2V, the wiring is misaligned and needs to be rewired.

Third, After measuring the voltage is normal, plug the wiring into the protection plate, and measure the resistance between the protection plate B- and P-, and the resistance is 0, indicating that they are unimpeded before and the protection plate is good.

Fourth, the voltage of B- and the total positive electrode of the battery and P- and the total positive electrode of the battery can also be measured by connecting B- line. The voltage is consistent, indicating that the protection plate is normal (the protection plate is equivalent to a switch, the switch has been turned on, and the current can pass safely). The sample test shows that the voltage from B- to the total positive electrode of the battery is 25.11VP- to the total positive electrode of the battery is 25.11V. The two voltages are consistent to indicate that the protection plate is normal. If P- is discharged through a large current, there will be a slight pressure drop, and the protection plate will be heated (about 50 degrees), which is a normal phenomenon.

Notes for testing lithium battery protection plate:

1. When measuring each series of voltage, the meter and pen should be put in the right position, or smoke will be caused by short circuit.

2. When connecting the protection board, make sure to connect the wiring before inserting the protection board. If the protective plate is inserted well and then connected with the wiring, it may burn out the protective plate.

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