Analysis of the balanced charging principle of batteries (valve-regulated sealed lead-acid batteries)

Valve-regulated sealed lead-acid batteries (hereinafter referred to as valve-regulated batteries) are widely used in practical applications due to their features of saving investment, easy installation, safety, reliability, and convenience. However, due to a lack of understanding of their use requirements and the use of the old equalization charging system, the batteries are greatly harmed.

1. Reasons for cancelling equalizing charging

(1) What is equalization charging?

The so-called balanced charging is charging to balance the battery characteristics. It means that during the use of the battery, the battery terminal voltage is unbalanced due to individual differences in the battery, temperature differences and other reasons. In order to avoid the deterioration of this imbalance trend, it is necessary to increase the charging voltage of the battery pack and activate the battery.

(2) Reasons why equalization charging is not necessary

First of all, the concept of balanced charging was proposed in the use of old lead-acid batteries. At present, most valve-regulated batteries clearly state that "voltage is balanced and formation is complete". However, "there is no acid layer formed in the battery, so balanced charging is not required". The definition of charging voltage for 2.4V single cells is accelerated charging, that is, "FASTCHARGE", not "EQUATION".

Secondly, equalizing charging will cause damage to valve-regulated batteries. For most batteries, the equalizing charging voltage is a relatively high floating charging voltage. At this time, most normal batteries are in an overcharged state. The gas that cannot be recombined forms a certain pressure inside the battery. When the pressure exceeds the threshold of the safety control valve, the valve opens and the gas is discharged from the control valve.

In the past, battery maintenance was accompanied by the process of equalizing charging, and the battery specific gravity was adjusted, that is, distilled water was added to replenish water to maintain the balance of the battery. However, in maintenance-free batteries, water is not added under the existing maintenance system, which will inevitably cause the battery to lose water and dry up.

[page]2. How to ensure the consistency of battery terminal voltage after canceling equalization charging?

(1) Determining factors of battery terminal voltage

First, it mainly depends on the concentration of the electrolyte and the plate material. When the battery loses water, the electrolyte concentration will inevitably increase, causing the battery terminal voltage to rise. Secondly, it is related to the opening of the safety valve. If the pressure of the safety valve is too low, the battery will lose water prematurely and the terminal voltage will rise. In addition, the connection status between the series batteries is different, and insufficient charging will occur during floating charge. When the battery encounters a deep discharge and then performs a restorative charge, it is difficult to recover, which will cause the battery terminal voltage to be low.

(2) Means of ensuring battery terminal voltage

Since the battery terminal voltage may be inconsistent and the battery is not allowed to be balanced charged, how can we ensure the consistency of the battery terminal voltage? First of all, the consistency of the battery voltage should be ensured from the raw materials and production links of the battery. For example, the selection of battery materials, especially the selection of key materials such as electrolyte, plate, and pressure control valve. Secondly, the quality of battery installation and the consistency of battery installation status should be ensured. For example, the battery connection method, torque balance, etc. In addition, attention should be paid to maintenance. For some backward batteries, recovery charging should be carried out, and the battery electrolyte should be properly adjusted; the working status of the pressure valve should be checked regularly.