The English name of valve-regulated lead-acid battery is Valve Regulated Lead Battery (VRLA battery for short). There is a one-way exhaust valve (also called a safety valve) on the cover. The function of this valve is to discharge the gas when the amount of gas inside the battery exceeds a certain value (usually expressed by the air pressure value), that is, when the air pressure inside the battery rises to a certain value. The gas valve opens automatically to discharge the gas, and then automatically closes the valve to prevent air from entering the inside of the battery.
The difficulty of sealing lead-acid batteries is the electrolysis of water during charging. When the charging reaches a certain voltage (generally above 2.30V/cell), oxygen is released on the positive electrode of the battery, and hydrogen is released on the negative electrode. On the one hand, the released gas brings out the acid mist to pollute the environment; Valve-regulated lead-acid battery is a product developed to overcome these shortcomings. Its product features are:
(1) Multi-element high-quality grid alloy is used to improve the overpotential of gas release. That is, ordinary battery grid alloy releases gas when it is above 2.30V/cell (25°C). After using high-quality multi-component alloys, the gas is released when the temperature is above 2.35V/monomer (25°C), which relatively reduces the amount of gas released.
(2) Let the negative electrode have excess capacity, that is, 10% more capacity than the positive electrode. In the later stage of charging, the oxygen released by the positive electrode contacts the negative electrode, reacts, and regenerates water, that is, O2+2Pb→2PbO+2H2SO4→H2O+2PbSO4, so that the negative electrode is in an undercharged state due to the action of oxygen, so no hydrogen is produced. The oxygen of the positive electrode is absorbed by the lead of the negative electrode, and then it is further converted into water, which is the so-called cathode absorption.
(3) In order to allow the oxygen released by the positive electrode to flow to the negative electrode as soon as possible, a new type of ultra-fine glass fiber separator that is different from the microporous rubber separator used in ordinary lead-acid batteries must be used. Its porosity is increased from 50% of the rubber separator to more than 90%, so that oxygen can easily flow to the negative electrode and then be converted into water. In addition, the ultra-fine glass fiber separator has the function of adsorbing the sulfuric acid electrolyte, so even if the battery is toppled, the electrolyte will not overflow.
(4) The sealed valve-controlled acid filter structure is adopted, so that the acid mist cannot escape, so as to achieve the purpose of safety and environmental protection.
In the above-mentioned cathode absorption process, since the generated water cannot overflow under the condition of sealing, the valve-regulated sealed lead-acid battery can be exempted from supplementary water maintenance, which is also the origin of the valve-regulated sealed lead-acid battery called dimension-free battery. However, the meaning of maintenance-free does not mean that no maintenance is done. On the contrary, in order to improve the service life of VRLA batteries, there are many maintenance tasks waiting for us to do. The correct use method can only be explored during the process. come out.
The electrical performance of lead-acid batteries is measured by the following parameters: battery electromotive force, open circuit voltage, termination voltage, working voltage, discharge current, capacity, battery internal resistance, storage performance, service life (float life, charge and discharge cycle life), etc.
Post time: Apr-26-2022
