How to distinguish the good and bad lithium battery

It is certainly safe to test the 18650 lithium battery with professional capacity tester, internal resistance tester and aging equipment, but this is a professional situation.

If you want to test the capacity of 18650 lithium battery, you can use comparison method. You need three things:

A standard capacity 18650 lithium battery

You can choose genuine Samsung 2600mah, stable quality.

A battery test container and circuit

Buy a solderless(spring-type) perfume portable power pack and use it as a battery test container and circuit.

A 1A load resistor

You can buy the fake load resistance (1A current) tested by charging battery online. Although it is made in a rough way, it is tested by comparison with the same one.

It's reliable.

Put the Samsung 2600mah battery into the mobile power test container, switch on the dummy load and start recording the discharge time. About 100 minutes until the load light goes off.

Get this basic parameter. Other batteries to be tested can be operated in the same way, and the obtained test parameters can be compared with the Samsung battery to know the approximate capacity of the battery to be tested.

Ready for multimeter, separately contact the multimeter pens and 18650 is the cathode of the battery, A simple voltage test, generally the real 18650 lithium iron batteries voltage at around 3.20 V, A product of the 18650 lithium battery voltage at around 3.8 V, bad 18650 fake batteries is generally low voltage or not, if A battery is false, then its output voltage of 0 V, according to A simple voltage test results will be able to distinguish between the stand or fall of the battery.

Prepare the internal resistance tester and put the 18650 battery into the internal resistance test fixture for internal resistance test. The fake 18650 battery has no internal resistance or the internal resistance value is very small, while the internal resistance of the 18650 battery of product A is generally less than 30 milliohms. A simple comparison based on the test result of internal resistance can also distinguish the quality of the battery.

If you want to make A clear distinction between the quality of the battery, you can prepare the battery compartment. After loading the battery into the cabinet, you can set the working step and the battery parameters in the corresponding specification book for capacity test. The capacity of product A after the capacity is up to the standard.

First 18650 batteries capacity is 2600mah batteries parameters to set standards, the lowest capacity is 2600mah capacity is 2550mah, internal resistance is not greater than 60, rated voltage 3.7 v, charging current C standard 0.2 C5, discharge current 0.2 C5, maximum charging current 1.0 C5, maximum discharge current 1.0 C5, maximum instantaneous discharge current 2.0 C5, charging voltage of 4.20 + / - 0.05 v, charging termination of current 1.0 C5, discharging termination voltage 3.0 v, working temperature - 10 to 60 ℃. The following is Gansu Zhongcheng energy lighting engineering co., ltd. to 18650 cell capacity of 2600mAH cell test process for detailed analysis.

First, charging process

(1) The standard charging it in the ambient temperature of 23 ℃ under the condition of plus or minus 2 ℃ with constant current charging C5A 0.2 to 4.20 V, to 4.20 V constant voltage charging flow of 0.02 C5A.

(2) The "quick charge" in the environmental temperature is 23 ℃ plus or minus 2 ℃ condition, at a constant C5A charging to 4.20 V, 0.5 to 4.20 V constant voltage charging to the current 0.02 C5A.

Second, Electrical performance

(1) 0.2 C5A discharge performance in environmental temperature is 23 ℃ under the condition of plus or minus 2 ℃ on 0.5 h - 1 h, and then to 0.2 C5A discharge current to end voltage. Discharge time is no less than 294min.

(2) in the batteries in the 55 ℃ high temperature performance of plus or minus 2 ℃ high temperature box in the constant temperature 2 h, then in 0.2 C5A current discharging termination voltage, discharge time not less than 5 h.

(3) the low temperature performance of the batteries to add - 10 ℃ + 2 ℃ low temperature box temperature 4 h, then in 0.2 C5A current to discharge voltage, discharge time not less than 3 h.

Third, Environmental performance test

(1) In vibration test, the cell is installed on the surface of the vibration table with a fixture, and the frequency sweep velocity is 10ct/min for 30min from 10--55Hz cycle in each direction, and the vibration frequency is 10-30 Hz displacement amplitude (single amplitude) is 0.38mm. The appearance of the cell has no obvious damage and leakage, and the smoke explosion open circuit voltage is not less than 90% of the initial voltage.

(2) The free drop test drops the cell from the position of 1m to the board of 18-20mm. After dropping 1 word from x,y,z plus or minus 6 directions, the cell is discharged at the current of 0.5ac5a to the termination voltage, and then the charge and discharge cycle is carried out at the current of 0.5c5a, no less than 3 times of charge and discharge. The cell does not leak liquid, smoke or explosion open circuit voltage is not less than 90%.

Fourth, Safety test

(1) Heavy impact: put the battery cell on the impact table and place the steel column of 15.8mm 2mm in the center of the battery. The 9.1kg 0.1kg hammer falls freely from the height of 610mm 25mm. Deformation of the battery cell is allowed.

(2) Charging: connect the batteries constant voltage power supply, adjust current 3 c5a, 10 v voltage and current is close to 0 a, batteries, when the temperature drops to about 10 ℃ lower than the peak, batteries are not on fire, no explosion.

(3) Short-circuit test: The battery with the thermocouple is placed in the fume hood, and the positive and negative poles are short-circuited with copper wire. During the experiment, the battery cell is monitored, the temperature changes, and the temperature drops to 10 ° C lower than the peak value to end the experiment. The battery core does not ignite, and the surface temperature of the non-explosive battery core is less than 150 ° C.

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