Types and classification of rechargeable batteries
Nickel-cadmium battery (Ni-Cd)
Voltage: 1.2V
Service life: 500 times
The discharge temperature is: -20 degrees to 60 degrees
Charging temperature: 0 degrees to 45 degrees
Remarks: Strong resistance to overcharge.
Ni-MH battery (Ni-Mh)
Voltage: 1.2V
Service life: 1000 times
The discharge temperature is: -10 degrees to 45 degrees
Charging temperature: 10 degrees to 45 degrees
Note: The current maximum capacity is about 2100mAh.
Lithium ion battery (Li-lon)
Voltage: 3.6V
Service life: 500 times
The discharge temperature is: -20 degrees to 60 degrees
Charging temperature: 0 degrees to 45 degrees
Remarks: The weight is 30%-40% lighter than Ni-MH batteries, and the capacity is more than 60% higher than Ni-MH batteries. But it is not resistant to overcharging, if overcharging will cause the temperature to be too high and destroy the structure => explosion.
Li-polymer battery (Li-polymer)
Voltage: 3.7V
Service life: 500 times
The discharge temperature is: -20 degrees to 60 degrees
Charging temperature: 0 degrees to 45 degrees
Remarks: The improved type of lithium battery does not have battery liquid, but instead uses polymer electrolyte, which can be made into various shapes and is more stable than lithium battery.
Lead-acid battery (Sealed)
Voltage: 2V
Service life: 200～300 times
The discharge temperature is: 0 degrees to 45 degrees
Charging temperature: 0 degrees to 45 degrees
Remarks: It is a general car battery (it is 6 2V series connected to form 12V), the battery life of the battery without adding water is up to 10 years, but the volume and maximum capacity are the largest.
Explanation of battery charging terms
Charging rate (C-rate)
C is the first letter of Capacity, which is used to indicate the magnitude of the current when the battery is charged and discharged.
For example: when the rated capacity of the rechargeable battery is 1100mAh, it means that the discharge time of 1100mAh (1C) can last for 1 hour. For example, the discharge time of 200mA (0.2C) can be
For 5 hours, charging can also be calculated according to this comparison.
Cut-off discharge voltage
When the battery is discharged, the voltage drops to the lowest working voltage value at which the battery is no longer suitable for discharging.
According to different battery types and different discharge conditions, the requirements for the capacity and life of the battery are also different, so the specified terminal voltage of the battery discharge is also different.
Open circuit voltage (OCV)
When the battery is not discharged, the potential difference between the two poles of the battery is called the open circuit voltage.
The open circuit voltage of the battery varies according to the materials of the battery's positive, negative and electrolyte. If the materials of the battery's positive and negative electrodes are exactly the same, then the open circuit voltage will be the same regardless of the size of the battery and how the geometric structure changes.
Depth of discharge DOD
In the process of battery use, the percentage of the battery's rated capacity is called the depth of discharge.
The depth of discharge has a deep relationship with the charging life of the secondary battery. When the depth of discharge of the secondary battery is deeper, the charging life will be shorter. Therefore, deep discharge should be avoided as much as possible during use.
Over discharge
If the battery exceeds the battery discharge termination voltage during the discharge process, the internal pressure of the battery may increase when the battery continues to be discharged, the reversibility of the positive and negative active materials will be damaged, and the battery capacity will be significantly reduced.
Over charge
When the battery is charging, if it continues to charge after it reaches a fully charged state, it may cause the internal pressure of the battery to increase, battery deformation, night leakage, etc., and the performance of the battery will also be significantly reduced and damaged.
Energy density
The electric energy released by the average unit volume or mass of a battery.
Generally, in the same volume, the energy density of lithium-ion batteries is 2.5 times that of nickel-cadmium batteries and 1.8 times that of nickel-hydrogen batteries. Therefore, when the battery capacity is equal, lithium-ion batteries will be better than nickel-cadmium and nickel-hydrogen batteries. Smaller size and lighter weight.
Self discharge
Regardless of whether the battery is used or not, due to various reasons, it will cause the phenomenon of power loss.
If calculated in a month, the self-discharge of lithium-ion batteries is about 1%-2%, and the self-discharge of nickel-hydrogen batteries is about 3%-5%.
Cycle life
When the rechargeable battery is repeatedly charged and discharged, the battery capacity gradually decreases to 60%-80% of the initial capacity.
Memory effect
During the charging and discharging process of the battery, many small bubbles will be generated on the battery plate. Over time, these bubbles will reduce the area of the battery plate and indirectly affect the battery capacity.
Basic requirements for charging and discharging rechargeable batteries
Will the newly purchased rechargeable battery need to be charged for 8-12 hours?
No matter any battery has the characteristic of self-discharge, so when a new rechargeable battery arrives in your hands, the rechargeable battery may have been self-discharged for a period of time. This is that the chemical raw materials inside the rechargeable battery have not been used for a period of time, and the "passivation" state appears, and the chemical reaction cannot be fully exerted to provide sufficient voltage. In this case, when using the rechargeable battery for the first time, be sure to fully charge the rechargeable battery to restore the voltage to its original level. In fact, if your rechargeable battery is not used for a long time, this "passivation" phenomenon will also occur, and the situation will be more serious. It is best to charge and discharge the rechargeable battery three times, which will help the rechargeable battery to activate. Let the chemical substances in the rechargeable battery give full play to its due effect (nickel-cadmium battery). Sometimes when a newly purchased rechargeable battery is put into the charger, the charger will stop charging before it is fully charged. When you encounter this kind of problem, you only need to remove the rechargeable battery from the charger, and then put it in the charger to continue charging. This is a normal phenomenon for new rechargeable batteries, and it is not that you have purchased bad rechargeable batteries (Ni-MH, Li-ion batteries). Generally speaking, the charging time cannot be too long, and up to 12 hours is sufficient. If overcharged, it will cause damage to the rechargeable battery.
How to calculate the charging time?
Charging time (hours) = rechargeable battery capacity (mAh) / charging current (mA) * 1.5 coefficient
If you use a 1600mAh rechargeable battery and the charger uses a current of 400mA to charge, the charging time is: 600/400*1.5=6 hours (note: this method does not apply to newly purchased or long-term unused rechargeable batteries)
Ni-MH rechargeable batteries and Li-ion rechargeable batteries actually have a memory effect, do they really need to be discharged when used?
In fact, the memory effect of the upper Ni-MH rechargeable battery and the lithium-ion rechargeable battery is very slight, and it is not worth our attention.
(Please note that when you see this, do not use the discharge function of the charger to discharge Ni-MH rechargeable batteries and lithium-ion rechargeable batteries, especially lithium-ion rechargeable batteries. Due to their own material factors, the battery itself is not allowed to withstand The forced discharge of the charger. If you insist on discharging the lithium-ion rechargeable battery, the battery will eventually be damaged.) In addition, if you use a nickel-cadmium rechargeable battery that needs to be discharged, it is recommended that you, regardless of whether the battery is used frequently or not, the most It is good to charge and discharge the nickel-cadmium rechargeable battery every two or three months, so as to ensure that the memory effect of the nickel-cadmium rechargeable battery is minimized.
The battery model knowledge is generally divided into: 1, 2, 3, 5, and 7, of which No. 5 and No. 7 are especially commonly used. The so-called AA battery is the No. 5 battery, and the AAA battery is the No. 7 battery! AA and AAA are all instructions The battery model; with the development of science and technology, dry batteries have developed into a large family, so far there are about 100 kinds. Common ones are ordinary zinc-manganese dry batteries, alkaline zinc-manganese dry batteries, magnesium-manganese dry batteries, zinc-air batteries, zinc-mercury oxide batteries, zinc-silver oxide batteries, lithium-manganese batteries, etc.
For the most used zinc-manganese dry batteries, they can be divided into different structures: paste-type zinc-manganese dry batteries, cardboard-type zinc-manganese dry batteries, thin-film zinc-manganese dry batteries, zinc chloride-zinc-manganese dry batteries, Alkaline zinc-manganese dry batteries, quadrupole parallel zinc-manganese dry batteries, laminated zinc-manganese dry batteries, etc.;
Zinc-manganese dry batteries are commonly used in daily life.
Cathode material: MnO2, graphite rod
Anode material: zinc flake
Electrolyte: NH4Cl, ZnCl2 and starch paste
The battery symbol can be expressed as
(-) Zn|ZnCl2, NH4Cl (paste) ‖MnO2|C (graphite) (＋)
Negative electrode: Zn=Zn2＋＋2e
Positive electrode: 2MnO2＋2NH4＋＋2e＝Mn2O3＋2NH3＋H2O
Total reaction: Zn＋2MnO2＋2NH4＋=2Zn2＋＋Mn2O3＋2NH3＋H2O
The electromotive force of the zinc-manganese dry battery is 1.5V. The generated NH3 gas is adsorbed by graphite, causing the electromotive force to drop rapidly. If the high-conductivity paste KOH is used instead of NH4Cl, and the cathode material is changed to a steel cylinder, the MnO2 layer is close to the steel cylinder to form an alkaline zinc-manganese dry battery. Due to the battery reaction, no gas is generated, the internal resistance is low, and the electromotive force is 1.5V. relatively stable.
Dry battery is a primary battery in chemical power supply. It is a kind of disposable battery. It uses manganese dioxide as the positive electrode and zinc cylinder as the negative electrode to convert chemical energy into electrical energy to supply an external circuit. In the chemical reaction, because zinc is more active than manganese, zinc loses electrons and is oxidized, while manganese gets electrons and is reduced.
