Battery performance and testing

1. What are the main characteristics of the secondary battery?

It mainly includes voltage, internal resistance, capacity, energy density, internal pressure, self-discharge rate, cycle life, sealing performance, safety performance, storage performance, appearance, etc. Others include overcharge, overdischarge, and corrosion resistance.

2. What are the reliability test items for the battery?

01) Cycle life

02) Different rate discharge characteristics

03) Different temperature discharge characteristics

04) Charging characteristics

05) Self-discharge characteristics

06) Storage characteristics

07) Overdischarge characteristics

08) Internal resistance characteristics at different temperatures

09) Temperature cycle test

10) Drop test

11) Vibration test

12) Capacity test

13) Internal resistance test

14) GMS test

15) High and low temperature impact test

16) Mechanical shock test

17) High temperature and high humidity test

3. What are the battery safety test items?

01) Short circuit test

02) Overcharge and over discharge test

03) Withstand voltage test

04) Impact test

05) Vibration test

06) Heating test

07) Fire test

09) Variable temperature cycle test

10) Trickle charge test

11) Free fall test

12) Low air pressure test

13) Forced discharge test

15) Hot plate test

17) Thermal shock test

19) Acupuncture test

20) Squeeze test

21) Heavy impact test

4. What are the common charging methods?

Nickel-metal hydride battery charging method:

01) Constant current charging: The charging current is a certain value in the whole charging process. This method is the most common;

02) Constant voltage charging: The charging power supply maintains a constant value at both ends during charging, and the current in the circuit gradually decreases as the battery voltage increases;

03) Constant current and constant voltage charging: The battery is first charged with constant current (CC). When the battery voltage rises to a certain value, the voltage remains unchanged (CV), and the current in the circuit drops to a small value, eventually reaching zero.

Lithium battery charging method:

Constant current constant voltage charging: The battery is first charged with constant current (CC), when the battery voltage rises to a certain value, the voltage remains unchanged (CV), the current in the circuit drops to a small value, and finally tends to zero.

5. What is the standard charge and discharge of NiMH batteries?

The IEC international standard stipulates that the standard charge and discharge of nickel-metal hydride batteries is: first discharge the battery to 1.0V / support at 0.2C, then charge at 0.1C for 16 hours, leave it for 1 hour, then put it at 0.2C / support at 0.2C, ie To charge and discharge the battery standard.

6. What is pulse charging? What is the impact on battery performance?

Pulse charging is generally done by charging and discharging, that is, chargingAfter 5 seconds, it is placed for 1 second, so that the oxygen generated during the charging process will be mostly reduced to electrolyte under the discharge pulse. It not only limits the amount of vaporization of the internal electrolyte, but also gradually restores or approaches the original capacity after charging and discharging 5-10 times using the charging method for those old batteries that have been heavily polarized.

7. What is trickle charging?

Trickle charging is used to compensate for the loss of capacity due to self-discharge after the battery is fully charged. Pulse current charging is generally used to achieve the above objectives.

8. What is charging efficiency?

Charging efficiency refers to the measure of the amount of chemical energy consumed by a battery during its charging process into a chemical energy that can be saved by the battery. Mainly affected by the battery process and the working environment temperature of the battery, the higher the general ambient temperature, the lower the charging efficiency.

9. What is the discharge efficiency?

Discharge efficiency refers to the ratio of the actual amount of electricity discharged to the rated voltage discharged under a certain discharge condition to the rated capacity. It is mainly affected by factors such as discharge rate, ambient temperature, internal resistance, etc. Under normal circumstances, the higher the discharge rate, The lower the discharge efficiency. The lower the temperature, the lower the discharge efficiency.

10. What is the output power of the battery?

The output power of a battery refers to the ability to output energy in a unit of time. It is based on the discharge currentCalculated by I and discharge voltage, P = U * I, in watts.

The smaller the internal resistance of the battery, the higher the output power, the internal resistance of the battery should be less than the internal resistance of the electrical appliance, otherwise the power consumed by the battery itself is greater than the power consumed by the electrical appliance, which is uneconomical and may damage the battery.

11. What is the self-discharge of the secondary battery? What is the self-discharge rate of different types of batteries?

Self-discharge, also known as charge retention, refers to the ability of the battery to store electricity under certain environmental conditions in an open circuit state. In general, self-discharge is primarily affected by manufacturing processes, materials, and storage conditions. Self-discharge is one of the main parameters for measuring battery performance. In general, the lower the battery storage temperature, the lower the self-discharge rate, but it should also be noted that if the temperature is too low or too high, the battery may be damaged and cannot be used.

After the battery is fully charged and left on for a period of time, a certain degree of self-discharge is normal.The IEC standard stipulates that the nickel-hydrogen battery is fully charged and has an open circuit for 28 days at a temperature of 20 ° C ± 5 ° C and a humidity of (65 ± 20) %. The 0.2 C discharge capacity reaches 60% of the initial capacity.

12. What is the 24-hour self-discharge test?

The self-discharge test of a lithium battery is:

Generally adopted24 hours self-discharge to quickly test its charge retention capacity, the battery is discharged to 3.0V at 0.2C, constant current and constant voltage 1C charge to 4.2V, off current: 10mA, after leaving for 15 minutes, 1C discharge to 3.0V The discharge capacity is C1, and then the battery is charged to 4.2V with constant current and constant voltage 1C, and the off current is 10mA. After being left for 24 hours, the 1C capacity C2 is measured, and C2/C1*100% should be greater than 99%.

13. What is the difference between the internal resistance of the charge state and the internal resistance of the discharge state?

Charge state internal resistance refers to batteryInternal resistance when 100% is fully charged; internal resistance in discharge state refers to the internal resistance after the battery is fully discharged.

Generally speaking, the internal resistance of the discharge state is not stable, and is too large, the internal resistance of the charge state is small, and the resistance value is relatively stable. In the use of the battery, only the internal resistance of the charge state has practical significance. In the later stage of the battery use, the internal resistance of the battery will increase to different degrees due to the depletion of the electrolyte and the decrease of the activity of the internal chemical substance.

14. What is a static resistor? What is dynamic resistance?

The static internal resistance is the internal resistance of the battery during discharge, and the dynamic internal resistance is the internal resistance of the battery during charging.

15. Is the standard overcharge test?

The standard overcharge test for nickel-metal hydride batteries specified by the IEC is:

Put the battery0.2C discharge to 1.0V / support, continuous charging at 0.1C for 48 hours, the battery should be free of deformation, leakage, and the time of 0.2C discharge to 1.0V after overcharge should be greater than 5 hours.

16. What is the IEC standard cycle life test?

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

Battery0.2C put to 1.0V / support

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

02) 0.25C charging for 3 hours and 10 minutes, discharging at 0.25C for 2 hours and 20 minutes (2-48 cycles)

03) 0.25C charging for 3 hours and 10 minutes, to 0.25C to 1.0V (49th cycle)

04) Charge at 0.1 C for 16 hours, set aside for 1 hour, and discharge 0.2 C to 1.0 V (50th cycle). For nickel-metal hydride batteries, after repeating 1-4 for 400 cycles, the 0.2 C discharge time should be greater than 3 hours; for nickel-cadmium batteries, repeat 1-4 for 500 cycles, and the 0.2 C discharge time should be greater than 3 hours.

17. What is the internal pressure of the battery?

Refers to the internal air pressure of the battery, which is caused by the gas generated during the charging and discharging process of the sealed battery, and is mainly affected by factors such as battery material, manufacturing process, and battery structure. The reason for this is mainly due to the accumulation of gas inside the battery and the gas generated by the decomposition of the organic solution in the battery. Generally, the internal pressure of the battery is maintained at a normal level. In the case of overcharge or overdischarge, the internal pressure of the battery may increase:

For example, overcharge, positive: 4OH- - 4e → 2H2O + O2↑; 1

The generated oxygen reacts with the hydrogen evolved on the negative electrode to form water. 2H2 + O2 → 2H2O 2

If the reactionThe speed of 2 is lower than the speed of reaction 1, and the generated oxygen is too late to be consumed, which causes the internal pressure of the battery to rise.

18. What is the standard charge retention test?

The IEC specifies the standard charge retention test for NiMH batteries as:

BatteryAfter 0.2C is placed at 1.0V, it is charged at 0.1C for 16 hours, at a temperature of 20 °C ± 5 °C, humidity of 65% ± 20%, after storage for 28 days, and then discharged to 0.2 V at 0.2 C, while nickel-hydrogen The battery should be more than 3 hours.

The national standard stipulates that the standard charge retention test for lithium batteries is: (IEC has no relevant standard) The battery is placed at 3.0C to 3.0/branch, and then charged to 4.2V with 1C constant current and constant voltage, the off current is 10mA, and the temperature is 20°C±5°C, after 28 days of storage, then 0.2C. Discharge to 2.75V, calculate the discharge capacity, and then be no less than 85% of the initial capacity compared to the nominal capacity of the battery.

19. What is a short circuit test?

Use a fully internal battery with an internal resistance in the explosion-proof enclosure≤100mΩ wire connection is shorted between positive and negative poles, and the battery should not explode or ignite.

20. What is the high temperature and high humidity test?

The high temperature and high humidity test of NiMH battery is:

After the battery is fully charged, it is stored under constant temperature and humidity conditions for several days, and no leakage is observed during storage.

Lithium battery high temperature and high humidity test is:(National standard)

Battery1C constant current constant voltage charging to 4.2V, off current 10mA, and then placed in (40 ± 2) ° C, relative humidity of 90% -95% in a constant temperature and humidity chamber for 48h, the battery is taken out (20 ± 5 Under the condition of °C for 2h, observe the appearance of the battery should be no abnormality, then discharge to 2.75V with a constant current of 1C, then carry out 1C charging and 1C discharge cycle under the condition of (20±5) °C until the discharge capacity is quite large. 85% of the initial capacity, but no more than 3 cycles.

21. What is the temperature rise experiment?

Put the battery fully charged and put it in the oven toThe temperature of 5 ° C / min starts from room temperature, and the oven temperature is maintained at 130 ° C for 30 minutes. The battery should not explode or ignite.

22. What is a temperature cycling experiment?

Temperature cycling experiment contains27 cycles, each consisting of the following steps:

01) The battery is switched from normal temperature to 66±3°C and placed at 15±5% for 1 hour.

02) Switch to a temperature of 33 ± 3 ° C, humidity of 90 ± 5 ° C for 1 hour,

03) Condition changed to -40 ± 3 ° C, placed for 1 hour

04) The battery is left at 25 ° C for 0.5 hours.

thisAfter 4 steps, the battery should be leak-free, climbing alkali, rust or other abnormal conditions.

23. What is the drop test?

Charge the battery or battery pack three times after chargingA height of 1 m falls onto the concrete (or cement) floor to obtain a random direction impact.

24. What is a vibration experiment?

The nickel-hydrogen battery vibration test method is:

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

amplitude:0.8mm

Make the battery atVibration between 10HZ-55HZ, increasing or decreasing at a rate of 1 Hz per minute.

Battery voltage change should beBetween ±0.02V, the internal resistance changes within ±5mΩ. (Vibration time is 90min)

The lithium battery vibration test method is:

BatteryAfter 0.2C discharge to 3.0V, the 1C charge constant current and constant voltage charge to 4.2V, the off current is 10mA, and after being left for 24 hours, it vibrates according to the following conditions:

At the vibration frequencyThe vibration experiment was carried out in 10 minutes from 10 Hz to 60 Hz to 10 Hz for a cycle with an amplitude of 0.06 inches. The battery vibrates in the triaxial direction and vibrates for half an hour per axis.

Battery voltage change should beBetween ±0.02V, the internal resistance changes within ±5mΩ.

25. What is the impact test?

After the battery is fully charged, place a hard rod on the battery and use aThe 20-pound weight fell from a certain height and slammed on the hard rod. The battery should not explode or ignite.

26. What is a penetration experiment?

After the battery is fully charged, use a nail of a certain diameter to pass through the center of the battery and leave the nail in the battery. The battery should not explode or ignite.

27. What is a fire experiment?

Place the fully charged battery on a heating device with a special protective cover to ignite and remove the protective cover without debris.