In outdoor travel, equipment such as cameras, mobile phones, GPS and flashlights are indispensable. Of course, power supply and batteries have become a problem that cannot be ignored, and rechargeable batteries are widely used. The following editor will popularize the knowledge about batteries for everyone.

　　Temperature characteristics: Since the migration rate of rechargeable batteries in the electrolyte and electrode sheets is closely related to temperature, fluctuations in temperature will significantly affect the technical performance of rechargeable batteries.

　　Storage temperature: Under normal circumstances, because the battery contains liquid inside, long-term storage at low temperatures will destroy the internal chemical substances of the battery. Therefore, it is recommended that the storage temperature should not be lower than -20°C under conditions; and too high temperature will also cause damage. The battery cannot reach its rated capacity. Generally, the storage temperature should not be higher than 40°C. The normal storage temperature of rechargeable batteries is -20℃～+65℃. When the temperature drops below -20℃, the electrolyte in the battery will solidify, the internal resistance of the battery will become infinite, and the battery will become unusable. When the temperature exceeds +65°C, the electrolyte will undergo side reactions and produce a lot of gas, and the resin adhesive in the electrode sheet will also deteriorate, which will cause the entire battery to gradually age and decline, and even fail in the short term.

　　Charging temperature: Generally, the charging temperature is between 0℃~45℃.

　　Discharge temperature: Under normal circumstances, the discharge temperature is -20℃~65℃; but in some special cases, low temperature batteries and high temperature resistant batteries can be used.

　　The battery pack is generally discharged before leaving the factory to prevent short circuit due to shock or other reasons during transportation. Usually, the new battery is not charged or only contains about 20% of the power.

　　New batteries or batteries that have not been used for a long time may not be fully activated due to the active material. Generally, two or three cycles of low current (0.1C) charging and discharging are required before use to reach the nominal capacity.

　　Batteries that will not be used for a long time should be stored in a charged state. Generally, they can be pre-charged with 50% to 100% of power and stored. It is recommended to charge the battery once every three months to restore the saturated capacity.

　　Battery use precautions:

　　Do not incinerate or disassemble the battery. The chemicals in it are corrosive and will harm the skin and eyes.

　　Do not pull the lead or plug of the battery to prevent damage to the solder joints and connections.

　　Different types of batteries cannot be mixed.

　　Welding on different types of batteries requires connecting pieces, etc. for welding.

　　Fully charge with a small current before the first use.

　　Do not charge in parallel, otherwise irregular charging current will occur.

　　Do not use the battery in reverse or short-circuit it.

　　After the battery is fully discharged, the charging time should be extended to reach the saturated capacity.

　　Please store the battery in a cool, ventilated and dry environment with a temperature not higher than 45°C.

　　When the battery is fully charged or half full, do not store a large number of batteries intensively.

　　Do not come into contact with acid gas, and avoid close to fire sources.

　　Primary battery: refers to a battery that cannot be charged but can only be discharged, but the capacity of the primary battery is generally greater than that of the same specification rechargeable batteries, such as zinc-manganese, alkaline dry batteries, lithium button batteries, lithium sub-cells, etc.

　　Secondary battery: refers to batteries that can be recharged and recycled, such as lead-acid, nickel-cadmium, nickel-metal hydride, lithium ion, lithium polymer, fuel, zinc, aluminum, magnesium-air batteries, etc.

　　Rated capacity: refers to the electric energy that can be released when the battery is fully charged and discharged to the cut-off voltage under no-load state, generally expressed in mAh or Ah (1Ah=1000mAh) symbols. However, if the battery is connected to a load during use and after long-term use, the amount of power released by the battery will decrease. Capacity Since charging and discharging are performed under a certain C-rate condition, the battery capacity is directly related to the C-rate. Normally, the nominal capacity of the battery refers to the electric capacity measured at 0.2C. The larger the C-rate, the smaller the discharge rate of the battery. Charging capacity (Ah or mAh) = charging current × charging time, and discharging capacity (Ah or mAh) = discharging current × discharging time. Generally speaking, 0.2C current discharge can basically reach 95%~100% discharge rate, while 1C current discharge can only reach about 90% discharge rate. Because charging is affected by the characteristics of battery raw materials, it needs more time to charge accordingly. It is 120~160% of the discharge time of the same current. For example, for NI-MHAA1800mAh, it takes about 6~8 hours to charge at 0.2C (360mA), and about 5 hours to discharge at 0.2C (360mA).

　　Rated voltage: refers to the potential difference caused by the chemical reaction of the positive and negative materials of the battery, and the resulting voltage value. Different batteries produce different voltages due to different positive and negative materials, such as lead-acid: 2V/cell, nickel-cadmium, nickel-hydrogen: 1.2V/cell, and lithium-ion battery: 3.6V/cell. In addition, the battery voltage will continue to rise to a certain value with the charging process, and will continue to drop to a certain value with the discharging process.

　　Open circuit voltage: refers to the voltage when the battery is not connected to an external circuit or external load. The open circuit voltage has a certain relationship with the remaining energy of the battery. Therefore, the battery display of the mobile phone is manufactured by using this relationship.

　　Internal resistance: Refers to the internal resistance of the battery automatically generated by chemical materials. Generally speaking, the smaller the internal resistance, the better the charge and discharge performance of the battery. The internal resistance of the battery is a very complex and very important characteristic, also known as the battery impedance, including DC resistance and AC resistance. The factors that affect the internal resistance of the battery include: ① the composition of the electrolyte; ② the composition of the positive and negative electrode sheets, such as the content of conductive carbon powder; ③ the geometric area and specific surface area of the positive and negative electrode sheets; ④ the metal substrate (copper foil and Aluminum foil); ⑤The state of the interface between the electrolyte and the positive and negative electrodes; ⑥Temperature; ⑦Charging status (open circuit voltage of the battery); ⑧Measurement frequency; ⑨The internal structure design of the battery.

　　C: It is used to express the ratio of the current when the battery is charging and discharging, that is, the magnification. For a 1200mAh battery, 0.2C means 240mA (0.2 times of 1200mAh), and 1C means 1200mA (1 times of 1200mAh). Charge and discharge efficiency The charge and discharge efficiency is also related to C (rate). Under the condition of 0.2C, the charge and discharge efficiency of the polymer lithium battery should be 99.8%. Charge and discharge efficiency=discharge capacity/charge capacity×100%

　　Discharge cut-off voltage: refers to the voltage reached when the battery is fully charged and discharged (if it continues to discharge, it will be over-discharged, which will greatly damage the life and performance of the battery). Generally speaking, lead-acid batteries: 1.8 V/cell, Ni-Cd, Ni-MH: 1.0V/cell, Li-ion battery: 2.75V/cell.

　　Open circuit voltage: refers to the voltage between the positive and negative poles of the battery when there is no load.

　　Depth of discharge: The ratio of the discharge capacity compared with the rated capacity of the battery.

　　Overcharge (discharge): Refers to the charging (discharging) state that exceeds the battery regulations. If the battery continues to be charged (discharged), it may cause battery leakage or deterioration.

　　Energy density: refers to the energy released per unit volume or unit mass, generally expressed by volume energy density (wh/l) and mass energy density (wh/kg).

　　Self-discharge: After the battery is fully charged, its capacity will naturally decay when it is not in contact with the external circuit and placed at room temperature. During storage, the battery capacity will gradually decrease. The ratio of the reduced capacity to the rated capacity is called the self-discharge rate (Ni-Cd and Ni-MH batteries have a higher self-discharge rate than lithium-ion batteries). Generally, the environmental temperature has a great influence on it, and excessively high temperature will accelerate the self-discharge of the battery. The expression method and unit of battery capacity decay (self-discharge rate): %/month. The self-discharge rate of nickel-cadmium and nickel-hydrogen batteries is 20-25%/month, and the self-discharge rate of lithium batteries is 2-5%/month.

　　Cycle life: The secondary battery undergoes one charge and discharge, which is called a cycle or a cycle. Under a certain discharge system, before the battery capacity drops to the specified value, the number of cycles that the battery undergoes is called the cycle life. The battery capacity will gradually decrease when the secondary battery is repeatedly charged and discharged. Generally, the rated capacity of the battery is used as the standard. The number of charge and discharge times when the battery capacity drops to 60% or 80% is called the cycle life.

　　Memory effect: The memory effect of a battery refers to the percentage of a fully discharged battery that can be charged the next time it is charged. In order to eliminate the memory effect of the battery, it must be completely discharged before charging in the second half, and then recharged. Only in this way can the battery be fully charged. The memory effect of the battery brings inconvenience to the fast charging of the battery. If the nickel-cadmium battery is charged without being discharged, the capacity may not return to the original standard, but it can be charged with a large current after deep discharge, and the capacity may be restored. Ni-MH and lithium batteries have no memory effect.

　　The single discharge voltage platform of lithium-ion batteries is higher, 3.6V, which is 3 times that of general batteries such as nickel-metal hydride and nickel-cadmium. Therefore, it is very suitable for occasions where a high discharge voltage platform is required. Due to the higher discharge voltage, the volume can be reduced a lot. The discharge voltage range of lithium-ion batteries is generally 2.5~4.2V/cell.

　　Lithium-ion batteries also have special requirements for use conditions, which require the voltage to be controlled at 2.5~4.2V/cell. If the voltage is too low during use, it will reduce the service life of the battery, and if the voltage is too high during charging, it may burst. Therefore, the lithium-ion battery cannot be used alone. It must be equipped with an electronic protection circuit to ensure that it works within the allowable range, so as to ensure the safety of the lithium-ion battery and effectively extend its service life. Due to the particularity of lithium-ion batteries, the requirements for chargers are also quite high. The most ideal charging method for lithium-ion batteries is constant current and constant voltage. First, charge with constant current to 4.2V/cell, and then convert to constant voltage. Charge. Charging ends when the current is low to a certain level. Lithium-ion batteries have higher requirements for the voltage accuracy of the charger. If the voltage is less than the rated (4.2V) 0.1V, it will lead to insufficient charging, which will reduce the charge by about 15%. If the voltage exceeds the rated voltage (4.2V) by 0.1V, it will cause overcharge and affect the battery life. In addition, the charging current of lithium-ion batteries should not be too large, and should match the battery capacity. Therefore, the lithium-ion battery charger must be a dedicated charger developed for its characteristics, and cannot be used in common with other battery chargers.