VRLA
From Wikipedia, the free encyclopedia
VRLA (also called Recombinant) stands for valve regulated lead acid and is the designation for maintenance-free lead-acid batteries. VRLA batteries can present several technologies such as:
- Absorbed glass mat battery
- Gel battery
These batteries are often colloquially called sealed lead-acid batteries, but this term is misleading: a sealed battery would be a safety hazard due to overpressure risks when overcharging, and there is always a safety valve present, hence the name valve-regulated. Sealed is opposed to vented (also called flooded). Because VRLA batteries use much less electrolyte (battery acid) than traditional lead-acid batteries, they are also occasionally referred to as an "acid-starved" design.
The name "valve regulated" does not wholly describe the technology; these are really "recombinant" batteries, which means that the oxygen evolved at the positive plates will largely recombine with the hydrogen ready to evolve on the negative plates, creating water--thus preventing water loss. The valve is strictly a safety feature in case the rate of hydrogen evolution becomes dangerously high.
One result of this design is a much higher ratio of power to "floorspace" than large, flooded type battery systems; another is a high-rate power capacity, though of relatively short duration. As a result, VRLA batteries are frequently employed in UPS (uninterruptible power supply) or other high-rate applications. Long duration applications such as telecommunications are not as well-suited to VRLA batteries, as there are other, more applicable battery designs available.
