A valve-regulated lead-acid (VRLA) battery, is a type of lead-acid battery characterized by a limited amount of electrolyte ("starved" electrolyte) absorbed in a plate separator or formed into a gel; proportioning of the negative and positive plates so that oxygen recombination is facilitated within the cell; and the presence of a relief valve that retains the battery contents independent of the position of the cells.
According to the technology, there are two kinds of lead-acid batteries: general type (AGM) and GEL. AGM battery uses glass fiber cotton (Absorbed Glass MAT) as a separator, and liquid electrolyte (the electrolyte is absorbed on plate and separator, and cannot flow in the battery). The GEL battery has silica as a solidifier and the electrolyte is adsorbed on the plate as colloid.
Accordingly, to using purpose, they also can be mainly divided by usage: starting batteries, stationary battery, and traction type, etc.
In the conditions of the stipulated design (such as temperature, discharge rate, and final voltage, etc.), the rated capacity means the battery should be able to release the lowest capacity, the unit is ampere-hour, expressed as a symbol of C. Capacity is strongly influenced by the discharge rate, so we often show the discharge rate by Arabic numerals at the lower right corner of the letter "C", such as C20=50Ah, it means that under the condition of 20-hour rate to discharge to the final voltage,the capacity is 50 ampere hours. Informally, the rated capacity of 50 ampere hour of battery in full charge of state, the battery can be discharged for 50 hours with 1 A of current.
Refers to the battery in the non-work state which the condition of the battery without any external load current flows, the Value of battery voltage between two terminals is measured by an electric meter. The Open circuit voltage measurement can not be utilized as a standard to measure the battery voltage, but it can be compared with each other, it also can determine different time change state of the charged battery itself, as a reference.
End of discharge voltage is the allowable minimum voltage of battery discharging.
When the battery voltage is lower than the end of discharge voltage, the voltage of the battery will drop rapidly if discharge it continuously, and it will cased over-discharge of battery, once the compound of battery plate is formed, and the plate will not easy to recover, which affect the lifespan of battery. The End of discharge is connected with discharge rate, and discharge current affect the end-of discharge voltage directly. Under the stated end of discharge voltage, the greater discharge current, the smaller capacity of battery.
When the battery is fully charged, the active material of the lead plates had reached saturation; the battery voltage does not raise anymore, even charge it continuously.
During battery using, the battery capacity is discharged a percentage of it rated capacity, we called depth of discharge, generally, DOD with 60%, which means the discharged capacity of battery reached 60%, and remained 40% of capacity. It’s a deep connection between depth of discharge and charging life, when deepen the DOD, the.
Recycling: The battery as a direct power supply of the equipment, which is mainly applied for circulation charge and discharge of Electrical hand tools, Portable electronic products and etc.
Float Use: The battery as an emergency power supply for equipment and system, to provide emergency power or energy storage, in order to prevent any inconvenience if any power interruption (Example: power plant, UPS power supply, emergency lighting, etc.)
There are mainly constant current charging, constant voltage charging, constant current with limiting voltage charging, equalizing charging, float charging and pulse fast charging.
Floating charging: A battery powered by a circuit when the normal power supply is interrupted. The terminal is always connected with a constant voltage power supply to maintain the battery in a close state of charge.
Equalizing charging: It is a continued charging way to ensure that each monomer of battery will be fully charged uniformly
There are several reasons as below,
① The battery charge is insufficient or the first charge is interrupted with a long time;
② Undercharge with long time.
③ Failed to charge timely after discharge;
④ Over discharging with small current or over charging frequently
⑤ The density of electrolyte or the temperature is too high, lead sulfate is formed and not easy to recover.
⑥ Battery stocked with a long time, and and it isn’t charged regularly.
⑦ The of electrolyte is impurity, which caused quickly self-discharge.
It requires good ventilation facilities, dry conditions (preferably with air conditioning), to maintain the environment temperature at around 25 degrees Celsius; and the ground to bear ability is strong, after 3 months storage should be charged.（The place where the battery installated should be safe and stable, and the battery should be charged once every 3 months stocked.
People used to mistakenly believe that the valve regulated lead acid battery is maintenance-free storage battery, so they are easily ignored the necessary maintenance. In fact, the battery change is a gradual process, in order to ensure the good use of the battery, it’s very important to make the operating records, the battery should be checked monthly as follows:
①The floating voltage of battery and battery group
②Temperature of the shell and pole of battery
③Battery shell with no deformation and seepage
④Any seepage or acid fog overflows at the side of pole or valv
⑤If the connection strip is tightened, Loose connection of the battery, it will increase the resistance of the joint, in the process of large current charging and discharging, it is easy to make the connector heating and even lead to the cove of battery melting. It may cause fire in serious condition
If the battery has been running for more than 4 years, the internal resistance increased correspondingly which may cause the difference of internal resistance for each battery; in this case, client should require the manufacturer to activate the battery, to reduce the internal resistance and regain the capacity.
Some manufacturers use the thick plate to improve battery service life, but it's difficult to control the uniformity of battery voltage, usually it needs to run more than 2 years and then the Voltage will gradually uniform, besides low battery voltage can also be to light discharge the whole battery group, to know battery discharge voltage is whether or not significantly lower, if lower, then we need contact manufacturer to dispose it.
If the battery has been running for more than 3 years, we’d better to conduct the discharge test once a year , Releasing 30 - 40 % of rated capacity ( rated capacity according to actual discharge rate calculation ) , capacity discharge test every three years , releasing 80% of the rated capacity and recording element voltage and total voltage .
The reaction of salinization begins when discharging the batteries, then transfers the activity of lead sulfate into spongy lead and lead dioxide in time, if the battery is placed more than 12 hours, the activity of the lead sulfate crystals become larger crystal particles once again, it will become irreversible sulfate.
Working under floating charge condition, it should be full discharged on a regular basis to refresh the battery’s plate material and test the actual capacity of the battery.
If the battery no time not put in using, it should be fully charging before storing, and at least once a month.
The mixture of new battery and old battery could cause the difference of loading current, so we should avoid mix them possible.
VRLA batteries should be installed away from heat and a place that easy to produce sparks, use in a clean environment. We recommend that battery room temperature between 15 degrees centigrade and 35 degrees centigrade the best way is to install an air-conditioner, control the temperature at about 25 degrees centigrade. Damp, Poor ventilation, solar radiation, and another bad environment will make the valve-regulated battery life shortened. Thus a clean environment, good ventilation, ambient temperature, and avoid direct sunlight are necessary. In addition, to facilitate battery maintenance, we should leave appropriate room space for maintenance when choosing a machine room.