Lifepo4 battery manufacturer Specialized in Energy Storage Battery since 2009.

Which method is better to charge the battery?

by:dcfpower     2021-03-17

Battery charging methods: constant current charging, constant voltage charging, pulse fast charging;

Battery charging types: initial charging, supplementary charging, desulfurization charging;

1. Constant current charging

(1) Definition: During the charging process, the charging current is constant (by adjusting the voltage to ensure that the current is constant).

(2) Advantages: The charging current can be selected arbitrarily, which is beneficial to prolong the battery life.

(3) Disadvantages: charging time is long, and the charging current needs to be adjusted frequently.

(4) Scope of application: initial charge, desulfurization charge and supplementary charge.

(5) Circuit characteristics: Each battery is connected in series. When charging, each cell needs 2.7V, so the total number of cells in series battery should not exceed nu003dUc/2.7 (Uc is the charging voltage of the charger).

(6) Charging requirements: The capacity of each battery cell should be the same as possible. When the capacity is different, the charging current should be determined according to the smallest capacity, and the small capacity battery should be removed after it is sufficient, and then continue to the rest of the batteries Recharge.

(7) Charging method (two-stage charging method)

1) Charge with a larger current in the first stage, when the cell voltage rises to 2.4V, the electrolyte starts Generate bubbles.

2) Reduce the charging current by half and perform the second stage constant current charging until the battery is fully charged.

2. Constant voltage charging

(1) Definition: During the charging process, the charging voltage is constant.

(2) Advantages

1) Fast charging speed. 90-95% of the power can be charged within 4-5h from the start of charging.

2) Easy to operate. The charging current will gradually decrease to zero as the electromotive force rises, so that the charging stops automatically, without manual adjustment and care.

(3) Disadvantages

1) The charging current cannot be adjusted, and the battery cannot be fully charged, and it is not suitable for initial charging and desulfurization charging.

2) The initial charging current is large, the temperature rises quickly, the electrode plate is easy to bend, the active material is easy to fall off, and it affects the life.

3. Pulse fast charging

(1) Polarization concept: In the chemical reaction at the later stage of charging, the potential difference between the two poles of the battery will be higher than the equilibrium potential of the active material of the two poles (per cell 2.1V), this phenomenon is called polarization.

(2) The influence of polarization: It hinders the normal progress of the chemical reaction of the battery charging process, which is the main factor causing low charging efficiency and long charging time.

(3) Polarization types: Ohmic polarization, concentration polarization, electrochemical polarization, etc.

(4) Solution: adopt pulse charging method.

(5) Pulse charging characteristics

1) Short time: new battery ≤5h, old battery 1-2h;

2) Power saving: electricity The amount is 80%-85% of conventional charging; (Constant current initial charging requires 60-70h; constant voltage supplementary charging requires 13-16h.)

3) Significant desulfurization effect;

4) Insufficient charging will affect the battery life.

(6) The pulse charging process uses pulse high current charging to realize fast charging.

①High-current constant-current charging Icu003d(0.8~1)C20, charging to 60% of the rated capacity in a short time, and the cell voltage rising to 2.4V;

② When the liquid is bubbling, stop charging for 24~30ms; ③Reverse pulse charging, Icu003d(1.5~3.0)C20

tu003d150~1000us, eliminate the bubbles in the pores

④ After stopping charging for 25ms, use the positive pulse to charge again, and so on until it is fully charged.

1. Initial charge

(1) Concept: the first charge for a new battery or a battery with a replacement plate.

(2) Function: To restore the electricity lost by the slow discharge and vulcanization of some active materials on the electrode plate during storage of the battery.

(3) Features: The charging current is small, the charging time is long (70-90h), and it must be completely sufficient.

(4) The impact of the initial charge quality on the battery:

1) The initial charge is insufficient: the battery capacity will be low for a long time and the life span will be shortened;

2) Excessive initial charge: The separators and plates are deformed due to corrosion, active material expansion, and gas pressure, which greatly reduces their service life.

(5) Procedure for initial charging

1) Filling electrolyte: the density meets the manufacturer's regulations (generally 1.25-1.285), and the liquid level meets the requirements (higher than the plate Edge 10-15mm). Requirements: The electrolyte temperature is filled with the front bucket at 30°C, and it is allowed to stand for 3-6h, until the electrolyte temperature at 35°C, and then recharge.

2) Determine the charging current

Constant current method Ic1u003dC20/15 Ic2u003dC20/303) Connect the battery (the positive electrode of the charger is connected to the positive electrode of the battery, and the negative electrode of the charger is connected to the negative electrode of the battery ), according to the two-stage charging method.

(6) Requirements for initial charging

①According to the current of the first stage, charge to a single cell charging voltage of 2.3-2.4V, stop the electro-hydraulic from escaping bubbles, change to the second stage Recharge the current.

②The charging voltage and electro-hydraulic density will not rise within 2-3h, and a large number of bubbles will stop.

③If the electro-hydraulic temperature rises to 40℃, the current must be halved; when the electro-hydraulic temperature rises to 45℃

, the charging should be stopped, and it will be restored when it is cooled to 35C Recharge.

(6) Requirements for initial charging

④ When the initial charging is nearing the end, the density of the electrolyte and the height of the liquid level should be measured. If the density is not suitable, use distilled water or 1.40g/cm3 After the electro-hydraulic adjustment, charge it for 2 hours, and recheck and adjust until it is suitable. Finally, screw on the vent plug and wipe the battery surface.

⑤Capacity check: After the initial charge of the battery is left for 1-2h, perform another discharge test at a discharge rate of 20h to check the battery capacity. The capacity of the new battery should be 0.95C20, otherwise it must be charged and discharged repeatedly until it meets the requirements.

2, supplementary charging

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