Floating charge characteristics of battery

　　 battery floating charge characteristics

　　(1) floating charge voltage:

　　 floating charge voltageu003dopen circuit voltage polarization voltage

　　u003d(electrolyte specific gravity＋0.85)V(0.10～0.18)V

　　The electrolyte specific gravity of valve-controlled battery is 1.30g/cm3, the open circuit voltage is 2.15V, so the floating charge voltage of the single cell is 2.25±0.02V/(25°C).

　　(2) Bias of battery terminal voltage (static deviation and dynamic deviation)

　　 valve-controlled battery terminal There are two voltage deviations, one is static voltage deviation, that is, open circuit voltage deviation, which should not exceed 20 mV; the other is dynamic deviation, that is, the large floating mortgage state deviation at the initial stage of floating mortgage operation, which runs for 2 months 3 It will gradually decrease after months. This is because the combined state of the oxygen cycle is unstable at the beginning of the operation. As the operating time increases, the recombination state of the oxygen cycle will become more and more stable, and the deviation of the terminal voltage will gradually decrease. Therefore, the terminal voltage deviation of the floating charge operating state should be greater than the static state.

　　 When the average floating charge voltage changes, the deviation value will also change. The higher the average floating charge voltage, the greater the deviation, but the deviation is reduced, but not proportional. At the end of the floating charge state, there is no direct relationship between the remaining capacity of the battery and the voltage. The remaining capacity of the battery is difficult to judge, but the low-voltage remaining capacity of the battery is smaller than the high-voltage capacity of the battery.

　　(3) Floating charge current of the battery

　　 The value of the floating charge current should meet the self-discharge current of the compensation unit Combined current with oxygen. Therefore:

　　If ≥ is me

　　 The self-discharge rate of valve-regulated sealed lead-acid batteries is very small, so the corresponding The floating charge current value is also very low. According to the Japanese standard, when the rated capacity is 80%, the overnight self-discharge rate does not exceed 0.2%. Even if calculated at 1%, the battery’s self-discharge current is measured at the specified temperature (20℃ or 25℃), ISu003d(C10 /24)×(1/100)u003d0.00042C10A, ISu003d0.42mA/Ah. In unit ampere time, taking into account the needs of oxygen cycle recombination, the floating charging current IFu003d1mA/Ah can meet the requirements.

　　 Since a large part of the self-discharge current (Is) is used for grid corrosion (let the corrosion current be Ic, Is≥Ic), due to the existence of oxygen recombination efficiency, there is only one A small part of the current is used to split water. In this way, different gate materials, different manufacturing processes, of course, the floating charging current is different. The smaller the floating charging current, the smaller the corrosion current to the grid, and the smaller the current used for water loss.

　　 (4) The relationship between floating charge current and battery life

　　 Battery life and grid corrosion rate and water loss The degree is closely related. Under the same alloy material conditions, the corrosion of the grid is related to the concentration of sulfuric acid and the temperature of the electrolyte: the higher the floating charge voltage of the battery, the higher the specific gravity of the electrolyte, the greater the floating charge current, and the greater the corrosion rate of the grid. This will also result in higher temperature, faster water loss and lower floating life of the battery. A smaller floating charging current will increase the lifetime of floating charging. Contact number: 0769-82771986