What is a VRLA battery

VRLA (valve regulated lead acid)

When developing lead-acid batteries, care was taken to ensure that the liquid sulfuric acid does not cause any damage in the event of accidents or incorrect treatment. They have been tied. With the lead fleece battery, the Absorbent Glass Mat (AGM), in a glass fiber fleece, and with the gel battery, Sealed Lead Acid (SLA), the sulfuric acid is bound with silica to form a gel.


The two battery types mentioned - the lead-fleece battery and the gel battery - are encapsulated so that they cannot leak, and are also provided with a safety valve through which the degassing takes place. This sealed design is called Valve Regulated Lead Acid (VRLA).

Valve Regulated Lead Acid (VRLA) does not adequately describe the pressure equalization, because electrolysis causes recombination between the oxygen generated at the positive electrode and the hydrogen generated at the negative plates within the VRLA batteries. This recombination is over 99% and is supported by the relatively constant internal pressure. The recombination creates water that compensates for the loss of water. The pressure valve only opens when too much hydrogen is generated.

VRLA batteries are sealed lead-acid batteries whose battery cells cannot be refilled with water and which require less gas to be vented than conventional lead-acid batteries. This has the advantage that such batteries can also be operated in poorly ventilated rooms.