CSB VRLA-AGM Valve-Regulated Sealed Lead-Acid Battery Technology Principles
Valve Regulated Lead Acid, abbreviated VRLA, is commonly referred to in Chinese as valve-regulated sealed lead-acid battery. It still belongs to the lead-acid family, but differs clearly from conventional flooded batteries: during normal use the battery remains sealed, and the gas generated internally recombines into water at the negative plate via the absorbent glass mat (AGM), escaping through the safety valve only when pressure becomes abnormal. This gives rise to maintenance-free, rechargeable, and leak-proof characteristics. CSB is one of the world's leading manufacturers of valve-regulated lead-acid batteries, with products sold in more than 100 countries and regions, and its entire VRLA product line is built on this technology.
The key function of the AGM is to provide a path for oxygen, allowing it to pass from the positive plate through the separator to the negative plate and recombine into water; official data shows a recombination rate of up to 99%. This mechanism greatly reduces electrolyte loss, so the battery requires no water replenishment throughout its service life. Paired with this are pure lead grid construction and a proprietary formulation—the grid conducts current and supports the active material, while the pure lead system helps slow corrosion, thereby extending float standby life. This is precisely why VRLA-AGM batteries are widely used in backup power applications that require long-term online operation with low maintenance needs.
On electrical parameters, VRLA-AGM ratings are specified at 25°C (77°F). For a 12V battery, float voltage falls between 13.5-13.8 Vdc, and equalize voltage between 14.4-15.0 Vdc, with actual values varying by model and cell construction. Design life is likewise given under float standby at 25°C, ranging from 5 years to 20 years, and some series also state a Eurobat (20°C) classification. As for temperature range, the nominal value is 25°C, the discharge range is -15°C~50°C, some series can reach -25°C~50°C, and the charge and storage range is -15°C~40°C. These conditions directly affect capacity correction and life estimation during selection.
As for the product lineup, CSB currently offers 142 models across 20 series, with voltages including 2V cells, 6V, 12V, and 512V lithium battery cabinets, capacity types from 4.5Ah to 1700Ah, and power types from 18W to 9000W (5–15 minute rate). The VRLA-AGM series are divided by application: data center UPS corresponds to HR, HRL, XHRL, XPL, XHT, etc.; telecom includes MSJ, MSV, MU, TPL, XTV, etc.; renewable energy includes RE, XTV-WT, etc.; general purpose covers GP and GPL; and electric mobility includes EVX and EVH. Each series differs in emphasis on terminal type, front or top access, cycle life, and high-temperature tolerance.
Understanding the principles of VRLA-AGM is very helpful for proper use and maintenance. Gas recombination requires suitable charging voltage and temperature conditions—overcharging or high temperatures accelerate water loss and grid corrosion, while undercharging causes sulfation, and both shorten actual life. Therefore, in real projects, charging equipment should be set according to the float and equalize ranges specified in the model data, while design life conditions should be evaluated in conjunction with ambient temperature. CSB model data also lists referenced standards such as IEC 61056, IEC 60896, IEC 60254, IEC 61427, and UL1989 Recognized for technical cross-reference.
