Lead-fleece batteries are high-performance lead batteries in which a glass-fibre fleece is saturated with the electrolyte
(sulphuric acid). This means that a lead-fleece battery, known as an Absorbent Glass Mat (AGM), has no free sulphuric acid and can be operated in all positions. Leakage of the acid is not possible even if the AGM battery breaks. AGM batteries have an extremely low internal resistance and can therefore supply higher discharge currents
forshort periods, for example during the starting phase of an engine. Due to the low internal resistance, the battery does not heat up even at high discharge currents. They are capable of deep discharge and have good capacity values even at low temperatures. AGM batteries are extremely robust and low-maintenance and can be charged and discharged several hundred times. Self-discharge
is usually less than 1% to 3% per month, which makes their recharge interval larger than other batteries.Valve Regulated Lead Acid (VRLA), and are therefore also called VRLA-AGM. These are encapsulated lead-acid batteries that balance the internal pressure via a valve.