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What is battery internal resistance?
It refers to the resistance that a battery experiences when the current flows through its interior during operation. It consists of two parts: ohmic internal resistance and polarization internal resistance. The high internal resistance of the battery can lead to a decrease in the discharge working voltage and a shortened discharge time. The size of internal resistance is mainly influenced by factors such as the material, manufacturing process, and battery structure of the battery. It is an important parameter for measuring battery performance. Note: The standard is generally based on the internal resistance in the charging state. The internal resistance of the battery needs to be measured using a dedicated internal resistance meter, rather than using a multimeter's ohmmeter range.
What is the capacity of a battery?
The capacity of a battery can be divided into rated capacity and actual capacity. The rated capacity of a battery refers to the minimum amount of electricity that is specified or guaranteed to be discharged under certain discharge conditions when designing and manufacturing batteries. For lithium-ion batteries, it is stipulated to fully charge them under charging conditions of 25 ± 2 ℃, constant current 0.5C - constant voltage 3.65V, and then discharge them from 0.5C to 2.5V as their rated capacity. The actual capacity of a battery refers to the actual amount of electricity released under certain discharge conditions, which is mainly affected by the discharge rate and temperature (therefore, strictly speaking, the battery capacity should indicate the charging and discharging conditions). The unit of battery capacity is Ah, mAh (1Ah=1000mAh).
What is the charging method for lithium batteries?
Intermittent charging: constant current limited voltage charging stage; Constant voltage current limiting charging stage; Open circuit idle stage of battery pack; Intermittent supplementary power stage.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 very small, eventually tending to zero.What is charging efficiency?Charging efficiency refers to the degree to which the electrical energy consumed by a battery during the charging process is converted into the chemical energy that the battery can store. Mainly affected by the battery process and the working environment temperature of the battery, the higher the ambient temperature, the lower the charging efficiency.
5. What is discharge efficiency?
Discharge efficiency refers to the ratio of the actual amount of electricity discharged to the rated capacity at the terminal voltage under certain discharge conditions. It is mainly affected by factors such as discharge rate, environmental temperature, internal resistance, etc. Generally, the higher the discharge rate, the lower the discharge efficiency. The lower the temperature, the lower the discharge efficiency.What is the output power of a battery?
The output power of a battery refers to its ability to output energy per unit of time. It is calculated based on discharge current 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 smaller than the internal resistance of the appliance, otherwise the power consumed by the battery itself will be greater than that of the appliance, which is uneconomical and may damage the battery.7. What is a 24-hour self discharge test?
The self discharge test of lithium batteries generally uses 24-hour self discharge to quickly test their charge retention ability. The battery is discharged at 0.5C to 2.5V, charged at constant current and voltage of 0.5C to 3.65V, with a cut-off current of 10mA. After being left for 15 minutes, the discharge capacity C1 is measured at 0.5C to 2.5V, and then charged at constant current and voltage of 0.5C to 3.65V with a cut-off current of 10mA. After being left for 24 hours, the 1C capacity C2 is measured, and C2/C1 * 100% should be greater than 99%.8. What is the charging state internal resistance?
What is the difference between discharge state internal resistance and discharge state internal resistance?
Charging state internal resistance refers to the internal resistance of a battery when it is 100% fully charged; Discharge state internal resistance refers to the internal resistance of a battery after full discharge.
Generally speaking, the internal resistance in the discharge state is unstable and relatively high, while the internal resistance in the charging state is small and the resistance value is also relatively stable. During the use of batteries, only the charging state internal resistance has practical significance. In the later stages of battery use, due to the depletion of electrolyte and the decrease in internal chemical activity, the internal resistance of the battery will increase to varying degrees.
9. What is static resistance? What is dynamic resistance?Static resistance refers to the internal resistance of the battery during discharge, while dynamic resistance refers to the internal resistance of the battery during charging.
10. Why do we need to transform into something?After battery manufacturing, the process of activating the internal positive and negative electrode materials through certain charging and discharging methods to improve the battery's charging and discharging performance, as well as the comprehensive performance of self discharge and storage, is called formation. The battery powder can only reflect its true performance after being formed.
11. What is capacity sharing?In the manufacturing process of batteries, due to technological reasons, the actual capacity of the battery cannot be completely consistent. The process of testing and classifying the battery according to capacity through a certain charging and discharging system is called capacity division.
12. What is pressure drop?
Qualitatively charge the battery to over 80% and measure its no-load voltage. The 5W/2W battery is used as a load to connect the positive and negative extreme switches of the battery as a circuit breaker, and the device for the circuit is connected in series. The voltage drop of no more than 0.4V within 5 seconds after turning on the switch is considered qualified, mainly for testing the load performance of the battery.
13. What is the load capacity of a battery?When the positive and negative terminals of the battery are connected to the appliance, the output power of the appliance during operation is the load capacity of the battery.
14. What is the rate discharge of a battery? What is the hourly discharge rate of a battery?Rate discharge refers to the representation of the rate relationship between the discharge current (A) and the rated capacity (A • h) during discharge. Hourly discharge refers to the number of hours required to discharge the rated capacity at a certain output current.What are the control methods to prevent battery overcharging?To prevent overcharging of the battery, it is necessary to control the charging endpoint. When the battery is fully charged, there are some special information that can be used to determine whether the charging has reached the endpoint. Generally, there are six methods to prevent the battery from being overcharged:01) Peak voltage control: Determine the charging endpoint by detecting the peak voltage of the battery;
02) dT/dt control: Determine the charging endpoint by detecting the rate of change in battery peak temperature;
03) △ T control: When the battery is fully charged, the difference between temperature and ambient temperature will reach its maximum;
04) - △ V control: When the battery is fully charged and reaches a peak voltage, the voltage will decrease by a certain value;
05) Timing control: Control the charging endpoint by setting a certain charging time, generally setting the time required to charge 130% of the nominal capacity.
What are the possible reasons for the short discharge time of batteries and battery packs?
The battery is not fully charged, such as insufficient charging time, low charging efficiency, etc; Excessive discharge current reduces discharge efficiency and shortens discharge time; When the battery is discharged, the ambient temperature is too low, resulting in a decrease in discharge efficiency.
17. What are the precautions when using batteries?
1) Before use, please read the battery manual carefully;
2) Cannot short-circuit the battery;
3) Do not disassemble or heat the battery, or throw the battery into water;
4) Batteries should be stored in a cool, dry place without direct sunlight.
Can batteries of different capacities be combined together?
If batteries of different capacities are mixed together for use, there is a possibility of leakage, zero voltage, and other phenomena. This is because during the charging process, the difference in capacity leads to some batteries being overcharged, some batteries not fully charged, and high capacity batteries not fully discharged during discharge, while low capacity batteries are over discharged. This vicious cycle causes damage to the batteries, resulting in leakage or low (zero) voltage.
19. What is an external short circuit and how does it affect battery performance?
Connecting the two ends of the battery to any conductor can cause an external short circuit. Different types of batteries may have different degrees of consequences due to short circuits. For example, the temperature of the electrolyte increases, the internal air pressure rises, and so on. If the pressure value exceeds the pressure relief valve pressure resistance value, the battery will leak liquid. This situation seriously damages the battery.What are the main factors that affect the service life of batteries?
01) Discharge:a. The depth of discharge is the main factor affecting the battery life, and the higher the depth of discharge, the shorter the battery life. In other words, as long as the discharge depth is reduced, the service life of the battery can be greatly extended. Therefore, we should avoid over discharging the battery to an extremely low voltage.b. If the designed electronic device cannot completely stop all current, and if the device is left unused for a long time without removing the battery, the residual current can sometimes cause excessive consumption of the battery, resulting in over discharge.c. Mixing batteries with different capacities, chemical structures, or charging levels, as well as new and old batteries, can also cause excessive discharge and even result in reverse charging.
02) Storage:If it is not a high-temperature battery, long-term storage at high temperatures will cause its electrode activity to decay and shorten its service life.
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