Absorbent Glass Mat Batteries or AGM Batteries are part of the VRLA (Valve Regulated Lead Acid) battery family. Most popular in the 1980’s, AGMs were used in military grade vehicles along with UPS applications. AGMs are close in design to Flooded Lead Acid Batteries. The main differentiation is that the electrolyte is contained in the battery by being absorbed into extremely porous microfiber glass separators, which are located between the batteries electrodes.
The process of absorption makes AGMs a maintenance free battery that is lightweight and more desirable, and VRLA (AGM or GEL) batteries can be installed without the fear of spilling the electrolyte.