NiMH No. 7 battery

Requirements for chargers for NiMH No. 7 battery - charging voltage and charging current

Requirements for chargers for NiMH No. 7 battery - charging voltage and charging current. The charging current and voltage of lithium iron phosphate battery packs are equally important. If the current or voltage does not match the battery, the lithium-ion battery cannot be charged normally and may even pose a safety hazard. The three important parameters of lithium-ion battery chargers are: 1. output current, 2. output voltage. 3. output power.

The negative electrode of a lithium-ion battery is a graphite crystal, and the positive electrode is usually lithium dioxide. When charging, lithium ions move from the positive electrode to the negative electrode and are embedded in the graphite layer. When discharging, lithium ions detach from the negative electrode surface in the graphite crystal and move to the positive electrode. Therefore, during the charging and discharging process of the battery, lithium always appears in the form of lithium ions, rather than in the form of metallic lithium. Therefore, this type of battery is called a lithium-ion battery, or lithium-ion battery for short.

Charge and discharge requirements of lithium iron ion battery pack

1. Charging of lithium ion battery pack: According to the structural characteristics of lithium ion battery pack, the maximum charge termination voltage should be 4.2V, and it should not be overcharged, otherwise the battery will be scrapped due to too many lithium ions taken away from the positive electrode. Its charge and discharge requirements are relatively high, and a dedicated constant current and constant voltage charger can be used for charging. Usually, constant current charging is switched to constant voltage charging after charging to 4.2V/cell. When the constant voltage charging current drops to less than 100mA, charging should be stopped.

Charging current (mA) = 0.1~1.5 times the battery capacity (such as a 1350mAh battery, its charging current can be controlled between 135~2025mA). The conventional charging current can be selected at about 0.5 times the battery capacity, and the charging time is about 2~3 hours.

2. Discharge of lithium-ion batteries: Due to the internal structure of the iron-lithium-ion battery pack, lithium ions cannot all move to the positive electrode during discharge, and a part of lithium ions must be retained in the negative electrode to ensure that the lithium ions can be smoothly embedded in the channel during the next charge. Otherwise, the battery life will be shortened accordingly. In order to ensure that some lithium ions remain in the graphite layer after discharge, the minimum discharge termination voltage must be strictly limited, that is, the lithium-ion battery cannot be over-discharged.

The discharge termination voltage is usually 3.0V/cell, and the minimum cannot be lower than 2.5V/cell. The length of the battery discharge time is related to the battery capacity and the discharge current. Battery discharge time (hours) = battery capacity/discharge current. The discharge current (mA) of the lithium-ion battery should not exceed 3 times the battery capacity. The NiMH No. 7 battery currently sold on the market are all sealed with matching charge and discharge protection boards. Just control the external charge and discharge current.

Requirements for iron-lithium-ion battery pack chargers—charging voltage and charging current

Lithium-ion battery chargers are chargers specifically used to charge lithium-ion batteries. Lithium-ion batteries have high requirements for chargers and need to protect the circuit, so lithium-ion battery chargers usually have high control precision and can charge lithium-ion batteries with constant current and constant voltage.

The basic requirements for lithium-ion battery pack chargers are specific charging current and charging voltage to ensure safe charging of the battery. Other charging auxiliary functions are added to improve battery life and simplify the operation of the charger, including trickle charging for over-discharged batteries, battery voltage testing, input current limiting, shutting off the charger after charging is completed, and automatically starting charging after partial discharge of the battery.

The charging method of lithium iron phosphate battery packs is voltage-limited constant current, which is controlled by IC chips. The typical charging method is: first test the voltage of the battery to be charged. If the voltage is lower than 3V, pre-charge it first, and the charging current is 1/10 of the set current. After the voltage rises to 3V, enter the standard charging process. The standard charging process is: constant current charging with a set current, when the battery voltage rises to 4.20V, change to constant voltage charging, and keep the charging voltage at 4.20V. At this time, the charging current gradually decreases, and when the current drops to 1/10 of the set charging current, the charging is completed.

Therefore, it is of great practical engineering significance to do a good job in the research of lithium-ion battery chargers, improve their reliability and operating efficiency, ensure the safety of the use of iron-NiMH No. 7 battery, and extend the battery life.

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