Thermal runaway in the constant voltage charging, the VRLA battery charge current and battery temperature of a cumulative enhancement and progressive damage to the battery. The root cause of thermal runaway is:
Common flooded lead-acid battery is full of liquid between the positive and negative plates, without gaps, so oxygen can not reach the anode, cathode produced in the process of charging, thus negative depolarization, easier to produce hydrogen, along with the oxygen to escape batteries .
Because dehydration can not dissipate VRLAB battery overcharge the heat generated in the course of more than flooded lead-acid batteries. More prone to thermal runaway.
Float voltage should be a reasonable choice. The float voltage charge voltage, battery long-term use is a crucial factor in battery life. Under normal circumstances, the float voltage set to 2.23V / monomer (25 ° C). Click here to float the scope of work, instead of using 2.35V / monomer (25 ° C), four consecutive charge appears to thermal runaway; mining 2.30V / monomer (25 ° C), continuous charging 6 ~~ 8 appears to thermal runaway; if the 2.28 V / monomer (25 ° C), row 12 to 18 months there will be serious capacity decreased, leading to thermal runaway. A direct consequence of the thermal runaway of the AGM VRLA battery casing bulge, leak, battery capacity, the final failure.
In fact, VRLA battery is always used in the ups system and its lifetime is defined as the period of time in which a battery is capable of being recharged and retains the charge applied. Once the battery is no longer capable of being recharged or cannot retain its charge properly, its lifetime reaches its end and it becomes a ‘used battery’ for the application it was designed for.
The lifetime of a VRLA battery is very dependent on its rate, conditions and kind of use. It is estimated to be between 1 up to 5 years. Depending upon manufacturer & product, expected life of all lead acid batteries will be cut in half for every 10-15 degree (F) rise in temperature over recommendation (usually 77 degrees F). For VRLA types, impact of excessive heat is most severe because it will lead to dry-out and open circuit failure, and in worst case scenarios in combination with older chargers, can contribute to thermal runaway, with explosive results.
Most UPS systems deep cycle batteries not just during outages, but also for changes in load levels as well as large dips in input voltage. In fact, many battery companies now limit warranties based upon the number & duration of these discharge cycles. Charge voltage, current and duration also has impact on VRLA reliability. Older or defective chargers can overcharge or add ripple current leading to heat buildup and premature failure.
Clearly, it is good idea to keep temperature controlled to 77 degrees F or less, and this is easily and regularly done. So temperature also has an important influence on the VRLA battery. Of course, if you don’t take care of these batteries, it also will shorten its life. All the factors could reduce the lifetime of AGM VRLA battery.
If you want the VRLA battery for longer time use, you should check and maintain it on a regular basis. Don’t forget to store it in a dry place with good ventilation. Never over charge it. Don’t let it deep discharge. So today it’s all. See you next time.
Gel battery is classified as one type of VRLA battery (The other type is VRLA AGM batteries). It has the same construction as AGM VRLA battery but has different electrolyte. The gel electrolyte is sulfuric acid combined with silica. These gel batteries use the extra microporous separator which can: reduce the depolarization of the negative electrode and avoid the PCL 3 effect (premature capacity loss due to negative plate sulphation); scientifically decreases thermal runaway; during deep discharge or pole reversal, help to prevent short circuits by dendrite growth between the plates.
Gel batteries have a few strong advantages that keep them on the market. They don’t typically leak, or produce spills or corrosion. Even if they are cut open, the gel does not flow out of the battery. The batteries are not known to evaporate, which is a constant issue with traditional wet batteries. They have a better resistance to extreme temperature changes, and are more vibration-resistant and shock-resistant than other types of batteries. Besides, these batteries can be left discharged for some time and they will still be able to recover to full capacity. They also do not develop a memory that limits the capacity of their recharging.
Are you interested in VRLA gel battery? Ok, go on reading my blog, and I will share more information with you here.
VRLA battery adopts sealing construction with no acid mist, no pollution gas overflowing, and it can be placed in upright or on side position. Due to the constant-voltage charging, the battery interior realizes the oxygen cycle process which has less water runaway. Although it is overcharged sometimes, the small quantity of gas can be exhausted through the security plugs so that the battery container with high pressure is not exploded. According to the different request of charging use and cycle use, it adopts regulation voltage to charge, and it doesn’t need any care when charging, and has no need to add distilled water, no need to inspect the voltage, proportion and temperature. But it needs to inspect the voltage and discharging capacity of batteries at regular intervals.
If the AGM VRLA battery is stored for over six months, it can be charged in accordance with the produced rule. When you fully charge it, you do a capacity trial discharging test to judge whether the battery capacity meets its request standard and the quality is reliable.
The majority of VRLA batteries used in Uninterruptible Power Supply (UPS) applications have a five (5) year design life. This design life is the basis for the manufacturer’s pro-rated warranties. The service life of a battery is the actual time span from the date of installation until the battery capacity drops below 80% of its rating. VRLA batteries that are well maintained and are installed in a properly conditioned environment, typically have a service life = 70%-80% of their design life.
The last point is that never let the VRLA battery over charge or deeply-discharge, or it might damage the battery. Of course, if you want to extend the life of AGM VRLA battery, you should pay attention to its battery maintenance. These articles are widely written in many webs, and you can look for it through google or bing. Good Luck to you.