VRLA battery
A valve regulated lead‐acid (VRLA) battery, commonly known as a sealed lead-acid (SLA) battery, is a type of lead-acid battery characterized by a limited amount of electrolyte ("starved" electrolyte) absorbed in a plate separator or formed into a gel, proportioning of the negative and positive plates so that oxygen recombination is facilitated within the cell, and the presence of a relief valve that retains the battery contents independent of the position of the cells. There are two primary types of VRLA batteries: absorbent glass mat (AGM) and gel cell (gel battery).