The maintenance-free battery is usually to complete two tasks, first of all, to restore the rated capacity as quickly as possible, and another task is to use floating charge supplement-free maintenance battery due to self-discharging power to maintain maintenance-free maintenance Rated capacity of the battery. In a sealed lead-acid battery, hydrogen and oxygen can be re-organized as water when the medium charge rate is employed.
Usually maintenance-free storage battery can reach more than 10 years. The life of the maintenance-free battery is usually divided into two kinds of cycle life and floating life. The capacity of the maintenance battery is reduced to the predetermined value, and the number of charge and discharge cycles of the maintenance-free battery is referred to as a cycle life. Under normal maintenance conditions, the maintenance-free battery floating charge is referred to as a floating life.
The initial charging time is related to the charging rate. When the charging rate is greater than C / 5, the maintenance-free battery capacity is restored to 80% of the release capacity, that is, the charging reaction begins. Only the charging rate is less than C / 100 to return the maintenance battery capacity to 100%, and then the charging reaction begins. When using a larger charging rate, in order to restore the capacity of the maintenance battery to 100%, a certain amount of overcharge must be allowed, the overcharge reaction occurs, the voltage of the battery is rapidly increased, reaches a certain value, decreases after a certain value. Then, the maintenance battery voltage begins to slow down. It can be seen that the best way to maintain the capacity of the maintenance-free battery capacity is the best way to maintain the battery capacity of the battery. That is to say, the charger should output a constant floating voltage after the battery is maintained.
2. Floating charge
(1) Floating voltage
Floating voltage = open circuit voltage + polarization voltage = (electrolyte density +0.85) V + (0.10 ~ 0.85) V + (0.10 ~ 0.18) v = 2.15V + 0.10V == 2.25V (single Maintenance-free battery of body 2V)
(2) Floating charge
There are two effects of the floating charge of ordinary lead-acid batteries: one is to supplement the loss of self-discharge of lead-acid batteries; the other is to provide current to the daily load.
There are three effects on the floating capacitance of the maintenance-free battery: one is to supplement the loss of self-discharge of the battery; the second is to provide current to the daily load; three is to maintain the maintenance-free battery in the oxygen circulation.
In the floating state, the current that is capable of maintaining the maintenance-free battery should be able to supplement the battery-free battery with the power-free battery and maintain the maintenance-free battery in the oxygen cycle. The floating voltage cannot be too high, so as not to shorten the life of the maintenance battery due to severe overcharge. Adopt appropriate floating charges, free-to-maintain the battery's floating life of more than 10 years. Practice has proved that the actual floating voltage is 5% different from the prescribed floating voltage, and the life of the maintenance battery will be shortened.
3. Deviation between terminal voltage
The dynamic deviation of the battery-side voltage is large in the initial period of floating operation. In fact, the maintenance-free battery that is just out of the factory may be due to the electrolytic liquid saturation state in the partial-free battery, thereby affecting the floating voltage Excessive, electrolyte saturation-free storage battery will decompose water due to constant charging“auto-adjust”To the unsaturated state, 6 months of rear end voltage deviation gradually decrease. However, the deviation is large and the manufacturing quality is not excluded.
4. Gas composite
At the normal floating charge voltage, the current is below 0.02c, and the gas is 100% composite, and the oxygen precipitation of the positive electrode is diffused to the negative surface. 100% in the negative electrode reduction, the negative oxygen around the negative electrode, and the hydrogen precipitated by the negative electrode is trace. If the floating voltage is increased, the ambient temperature is increased, the charge is raised, and the gas re-adact efficiency becomes smaller with the charge current, and the composite rate is 90% at 0.05c, when the current is 0.1c, gas The reincarnation efficiency is approximately zero. As shown in Figure 3, there are many hydrogen from the oxygen and negative surfaces of the negative electrode and the negative surface of the negative electrode surface, and the internal pressure of the battery is sealed, and the exhaust valve is opened, resulting in a maintenance-free battery.
5. Effect of temperature
The internal gas composite itself is an exothermic reaction when the battery is charged, so that the temperature of the maintenance battery is increased, the floating charge is increased, the quantity is increased, and the maintenance battery temperature is higher, the maintenance battery itself is“Lean liquid”The assembly is close, internal heat dissipation is difficult, if it is not removed in time, it will cause thermal out of control. The final voltage of the floating charge is too high, and the ambient temperature of the maintenance-free battery will increase the maintenance-free battery thermal out of control.
The voltage and temperature of the maintenance-free battery have a lot of relationships, and the temperature is 1 ¡ã C per liter, and the voltage of the battery will drop the voltage of the battery will drop by about 3 mV / monomer-free maintenance battery. That is, the voltage of the maintenanceable battery has a negative temperature coefficient, its value is -3 mV / ¡ã C. It can be seen that when the ambient temperature is 25 ¡ã C, it works ideal, when the ambient temperature drops to 0 ¡ã C, the maintenance-free battery can not be fully charged, when the ambient temperature rises to 50 ¡ã C, the maintenance-free battery overcharge The maintenance-free battery will shorten the life due to severe overcharge. When the temperature is below -40 ¡ã C, the maintenance-free battery can also work normally, but the maintenance battery capacity will be reduced. Therefore, in order to ensure that the maintenance-free battery can be fully charged in a wide temperature range, the various conversion voltages of the charger must freely maintain the voltage temperature coefficient of the battery.
Demand-free battery due to structural problems high, for this purpose, temperature compensation measures should be considered when designing charging equipment, but the selection of temperature sampling points is critical, it directly related to compensation.
There are three temperatures, that is, the air temperature near the battery is exempted, and the surface temperature of the battery housing is maintained, and the internal electrolyte temperature of the battery is maintained. The first place is easier, but this method is very incorrect, because some reason enhances the temperature of the maintenance battery temperature, but the rise-free battery temperature increases difficult to cause the air temperature near the maintenance-free battery, so this The compensation measures are basically useless; the third point is best reflected in the actual situation of the maintenance-free battery, but it is more difficult to implement; the second place is most practical, and it is also easier to implement, and the sampling design temperature compensation unit of the second place is basically basically used.
6. Effect of electrolyte formula on discharge performance of high-magnification free maintenance battery
For a long time, the impact of the maintenance of the maintenance-free battery performance after the addition of an additive in the electrolytic solution at home and abroad has been studied. Due to the use of the electrolytic liquid additive, there is no change in the production process of the maintenance-free battery industry, the additional cost, good effect, easy promotion, etc. The role of the maintenance-free battery electrolyte additive can be attributed to the following points:
1) Enhance electrolyte electrolyte conductance, improve capacity recovery performance and recharge acceptance capacity after-maintainable battery over-discharge.
2) Inhibit the occurrence of dendritic short circuit.
3) High-free capacity of the battery and inhibit early capacity loss.
4) Prevent softening, falling off and slowing the corrosion of the grid.
In the experiment, some additives have only the above effects, while others have several effects at the same time. Therefore, a combined electrolyte formula should be used to alter the composition of the electrolyte, so that the discharge performance of the maintenance-free battery is imp
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