Fast charging of lead-acid batteries

The voltage amplitude of the charging pulse remains constant. As the charging progresses, the battery electromotive force gradually rises, the charging current amplitude gradually decreases, and the frequency of the charging pulse current is constant. A discharge depolarization pulse is added between the two pulses.

 

Under general conditions, lead-acid batteries are charged with a current less than the discharge (less than 10% of the rated capacity). The charging method with a current greater than this is called fast charging. Under normal circumstances, conventional charging is used, and fast charging is only used in special emergency situations.
 

The amount of outgas is an important indicator of the degree of chemical reaction in the battery charging process. The gas output refers to the total gas weight when the pressure of the gas deposited on the positive and negative plates reaches 0.1 MPa during the entire charging process of the battery; the gas output rate refers to a certain stage of charging, under 0.1 MPa pressure, the positive and negative plates are precipitated per unit time Gas weight. During the charging process, outgassing will cause the electrolyte to flow out from the pores of the electrode plate, affecting the chemical reaction of the battery and reducing the charging speed. When the outgassing rate is too large, the generated gas will make the active material fall off, affecting the capacity and life of the battery. In order to extend the battery life and increase the charging speed, the gas outlet rate should be reduced as much as possible.

 

When the lead-acid battery is charged quickly, it will produce a higher temperature rise and shorten the battery life. Generally, the temperature rise should be controlled within 45 ℃.
 

Refers to the number of charge and discharge cycles that the battery can reach during fast charging. Lead-acid batteries use fast charging and have a lower life than conventional charging.
 

 

A gas sensor is used to detect the rate of gas evolution from the battery, thereby controlling the charging current. At the beginning of charging, it is charged with a large current. When the gas generated in the battery reaches a certain value, according to the change of the sensor parameter, a control signal is sent to the charging circuit to reduce the charging current to maintain a constant gas output rate. This method cannot be used to charge sealed or maintenance-free batteries. High current charging time should be within 30 minutes.
 

The charging current is controlled by detecting the amount of electricity charged into the battery. To charge with this method, it is necessary to grasp the different charging states of the charging process, thereby controlling the charging current.
 

Under the condition that the charging voltage is determined and maintained at a certain constant value, fast charging is performed. In the initial stage of charging, the battery voltage is lower and the charging current is larger. As the charging progresses, the current gradually decreases. The method is simple and the control system is easy to implement.
 

Temporarily interrupt the charging current and measure the voltage immediately before resuming charging to keep it at a constant voltage without load. This voltage does not include the internal resistance voltage drop of the battery. This method is suitable for batteries with different structures, different service years and different charging states.
 

The battery is charged with a pulse charging current with a constant current amplitude and a constant period, and a discharge pulse is depolarized between the two charging pulses to improve the charging acceptance of the battery. During the charging process, the charging current and its pulse width are not affected by the state of charge of the battery. This method is easy to fill the battery, but if no protection device against overcharging is added, it is easy to cause overcharging.
 

During the entire charging process, the amplitude of the charging current pulse and the outgassing rate of the battery remain unchanged. The method is to send a control signal in time through the gas sensor to force the battery to stop charging and discharge for a short time. The polarization inside the battery disappears quickly, and the outgassing rate is always kept at a low value.
 

Charging with a constant large current, when charging to the outlet voltage of the battery, stop charging and discharge, and then carry out high current charging, the charging and discharging process alternately in turn. The width of the discharge pulse increases with the amount of charge, and the width of the charge pulse decreases with the increase of charge. When the charge capacity and discharge capacity are basically equal, it indicates that the battery is almost fully charged and the charging is ended immediately.
 

The voltage amplitude of the charging pulse remains constant. As the charging progresses, the battery electromotive force gradually rises, the charging current amplitude gradually decreases, and the frequency of the charging pulse current is constant. A discharge depolarization pulse is added between the two pulses.