What does AGM battery mean https://www.renogy.com/blog/wh....at-is-an-agm-battery In AGM (Absorbed Gl**** Mat) batteries the electrolyte is held in place by a separating membrane. This is why these batteries are also known as membrane batteries. The membrane consists of a fibergl**** mat and functions as a sponge. This function is based on the capillary properties of the membrane. AGM batteries can be produced using very thin separating membranes, leading to low internal resistance. This means that high output power can be achieved with batteries of relatively low size, making this type of battery ideal for a wide variety of application