How many test methods for lithium batteries?

How many test methods for lithium batteries?

Lithium battery requires high quality and high safety. Consumers often don't know performance of battery when using it. As a result, battery's working efficiency often not so good. Sometimes wrong use way may cause explosion and hurt ourselves. Therefore it's necessary to understanding battery performance.

Lithium battery performance test mainly includes voltage, internal resistance, capacity, internal pressure, self-discharge rate, cycle life, sealing performance, safety performance, storage performance, appearance, etc., and other overcharge, over discharge, weldability, corrosion resistance Sex and so on.

Tools/raw materials

Tester, hard rod, nail.

Method / step

Method 1, self-discharge test

The self-discharge test of nickel-cadmium and nickel-hydrogen batteries is: because the standard charge retention test time is too long, the 24-hour self-discharge is generally used to quickly test the charge retention capability, and the battery is discharged to 1.0V.1C for charging at 0.2C. Minute, let stand for 15 minutes, discharge to 10V at 1C, measure its discharge capacity C1, then charge the battery at 1C for 80 minutes, and set the 1C capacity C2 after 24 hours, C2/C1×100% should be less than 15%.

The self-discharge test of lithium battery is: generally adopt 24-hour self-discharge to quickly test its charge retention capability, discharge the battery to 3.0V at 0.2C, constant current and constant voltage 1C charge to 4.2V, cut-off current: 10mA, shelving 15 After a minute, the discharge capacity C1 is measured by discharging from 1C to 3.0V, and then the battery is charged to 4.2V with a constant current constant voltage of 1C, the off current is 100mA, and the 1C capacity C2 is measured after being left for 24 hours, and C2/C1×100% should be greater than 99. %.

Method 2, internal resistance measurement

The internal resistance of the battery refers to the resistance that the current is flowing through the battery when it is working. It is generally divided into AC internal resistance and DC internal resistance. Since the internal resistance of the rechargeable battery is small, the internal resistance of the DC is easily polarized due to the electrode., the polarization internal resistance is generated, so the true value cannot be measured; and the internal resistance of the AC can be removed to avoid the influence of the polarization internal resistance, and the true internal value is obtained.

The AC internal resistance test method is: using the characteristics of the battery equivalent to an active resistor, the battery is given a constant current of 1000HZ, 50mA, and a series of processing such as voltage sampling rectification and filtering to accurately measure the resistance value.

Method 3, IEC standard cycle life test

The IEC specifies the standard cycle life test for nickel-cadmium and nickel-hydrogen batteries as:

After the battery is placed at 0.2C / 1.0V / support

1. Charge at 0.1C for 16 hours, then discharge at 0.2C for 2 hours and 30 minutes (one cycle).

2.0.25C charging for 3 hours and 10 minutes, discharging at 0.25C for 2 hours and 20 minutes (2-48 cycles).

3.0.25C charging for 3 hours and 10 minutes, to 0.25C to 1.0V (49th cycle)

4.0.1C charging for 16 hours, leaving for 1 hour, 0.2C discharge to 1.0V (50th cycle), after repeating 1-4 for 400 cycles of nickel-hydrogen battery, the 0.2C discharge time should be greater than 3 hours; The battery is repeated for 1-4 cycles of 500 cycles, and its 0.2C discharge time should be greater than 3 hours.

The IEC specifies the standard cycle life test for lithium batteries as:

After the battery is placed at 0.2C to 3.0V/branch, 1C constant current and constant voltage is charged to 4.2V, the off current is 20MA, and after being left for 1 hour, it is discharged to 0.2V (one cycle) and repeated for 500 times. More than 60% of the initial capacity.

Method 4, internal pressure test

The internal pressure test of nickel-cadmium and nickel-hydrogen batteries is:

After the battery was placed at 1.0C to 1.0V, it was charged at 1C for 3 hours. According to the slight deformation of the battery steel shell, the internal pressure of the battery was obtained by conversion. The battery should not be bottomed, leaked or exploded during the test.

Lithium battery internal pressure test is: (UL standard)

The simulated battery is tested for leaking or damming the battery at an altitude of 15240 m (low pressure 11.6 kPa).

Specific steps: charge the battery 1C to constant current and constant voltage to 4.2V, cut off current 10mA, and then store it in a low-voltage box with a gas pressure of 11.6Kpa and a temperature of (20±3°C) for 6 hours, the battery will not explode., fire, crack, leaking.

Method 5, drop test

After the battery pack is fully charged, it will fall on the hard rubber board from three different directions at a height of 1 m, and it will be done twice in each direction. The battery pack should have normal electrical performance and the outer packaging is not damaged.

Method six, vibration test

The experimental methods for vibrating nickel-cadmium and nickel-hydrogen batteries are:

After the battery was discharged to 1.0 V at 0.2 C, it was charged at 0.1 C for 16 hours, and after being left for 24 hours, it was vibrated under the following conditions:

Amplitude: 4mm

Frequency: 1000 times, vibrating for 30 minutes in three directions of XYZ.

After vibration, the battery voltage should be within ±0.02V, and the internal resistance should be within ±5m.

The lithium battery vibration test method is:

After discharging the battery to 0.2V at 0.2C, the constant current constant voltage is charged to 4.2V, and the off current is 10mA. After being left for 24 hours, it vibrates according to the following conditions:

Amplitude 0.8mm

The battery is vibrated between 10HZ-55HZ, increasing or decreasing at a vibration rate of 1HZ per minute.

After the vibration, the battery voltage should be changed within ±0.02V, and the internal resistance should be changed within 5m.

Method seven, impact test

After the battery is fully charged, place a 15.8mm diameter hard rod on the battery, drop it from a height of 610mm with a 20-pound weight and smash it on the hard rod. The battery should not explode or leak.

Method eight, puncture experiment

After the battery is fully charged, use a nail with a diameter of 2.0mm~25mm to pass through the center of the battery and leave the nail in the battery. The battery should not explode.

Method IX, high temperature and high humidity test

The high temperature and high humidity test of nickel cadmium and nickel hydrogen battery is:

After discharging the battery to 0.2V at 0.2C, after charging for 1 minute at 1C, it is placed at a temperature of 66 ° C, stored at 85% humidity for 192 hours (8 days), and left at room temperature and humidity for 2 hours. The battery should not be deformed or Leakage, capacity recovery should be more than 80% of the nominal capacity.

Lithium battery high temperature and high humidity test: (national standard)

Charge the battery 1C with constant current and constant voltage to 4.2V, cut off current 10mA, then put it in (40±2°C), and hold it in the constant temperature and humidity chamber with relative humidity of 90%-95% for 48h, then take out the battery (20 Under the condition of ±5 °C), it should be left for 2h. Observe the appearance of the battery should be no abnormality, then discharge to 2.75V with 1C constant current, then charge at 1C under the condition of (20±5°C), 1C discharge cycle until discharge capacity not less than 85% of the initial capacity, but the number of cycles is not more than 3 times.

Precautions

Test time set aside for 24 hours

Loop test is not redundant three times

The page contains the contents of the machine translation.