Valve Regulated Lead Acid Battery- All You Need to Know

Valve Regulated Lead Acid Battery is like google, existing everywhere but nowhere to be seen. Even your ride (or rides) might also be VRLA powered. We’ll never know if Robo-Cop had one or not!  

But, this might not be all of this battery.

The first Lead Acid Gel battery was created in 1934. But, since then these batteries have gone through many modifications. 

Later in 1957, the modern lead-acid battery, or as we call it, Value Regulated Lead Acid Battery was created. 

You’ll be surprised to know that even an aircraft manufacturing company started using these batteries on their aircraft. 

Let’s see the mystery behind this powered cell, shall we?

What is A Value Regulated Lead Acid Battery?

A Value Regulated Lead-Acid battery is some type of rechargeable battery. People generally refer to them as maintenance-free or sealed batteries. 

Lead-acid batteries are made up of a succession of lead-acid cells in the same container. You see, two lead plates are suspended in a fluid-like electrolyte mixture of sulfuric acid in lead-acid cells.

Sealed Lead Acid (SLA) and Valve Regulated Lead Acid (VRLA) are two distinct names for the same type of battery. Here are the features you will find in these batteries:

  • Maintenance-free 
  • Leak-proof 
  • Insensitive to positioning. 

Moreover, these batteries have a safety valve that allows gas to escape. As a result, there won’t be any internal pressure inside the battery.

Absorbed Glass Mat (AGM) is a kind of SLA/VRLA in which the electrolytes are absorbed into dividers between the plates. Inside the plates, sponge-like thin glass fiber sheets do the magic.

For many years, lead-acid batteries have been the most frequently utilized energy storage device ( for both medium-scale and large-scale applications). 

In recent times, an alternate design has started to replace the old, flooded form of the battery. 

This new valve-regulated lead-acid (VRLA) battery, does not require the electrolyte solution to be refilled with water. It does not leak liquids and may be used in almost any configuration.

The VRLA battery functions differently than its predecessor. The creators had to ensure significant technological progress to fulfill the demanding complete spectrum of rechargeable battery applications.


How Does Valve Regulated Lead Acid Battery Work?

When in operation, the battery creates electricity by decreasing the lead plates and converting them to lead sulfuric oxide.

As soon as the battery is fully charged, the system is reversed. Then the lead sulfuric oxide is degraded into pure sulfuric and lead-acid because the reverse process isn’t flawless.

Hydrogen gas is discharged before it has a chance to fully combine with the water inside. 

A duct is used to release pressure and avoid the build-up of hydrogen gas. Your battery might even explode if it fails to release the glass. 

VRLA batteries restrict the electrolyte from moving about inside the container. This confines hydrogen close to the plates. That makes it easy for recombination when the battery is fully recharged. 

This design significantly decreases water loss throughout the discharge and recharge cycle. Allowing the battery to be maintenance-free and sealable. 

As a result, you can use these batteries in whatever configuration you choose without worrying about leakage.

One of two things can occur when charging is completed: 

  1. The gas buildup could be too fast for recombination with the water, and/or
  2. The electrolytes may boil, resulting in excessive pressure.

A one-way pop-off mechanism is built into the battery body to control these events. It only releases when pressure builds up in the battery. 

The immobilizer installed in these batteries guarantees that the liquid within does not spill or leak out.

Types of VRLA Batteries

VRLA batteries are of two types. Absorbed Glass Mat (AGM) and Gel Cell. Now, let’s look at them in detail-

Absorbed Glass Mat (AGM)

The acid is extracted and stabilized by very fine fibreglass mats. The mats are placed in between the plates in this sort of battery. 

This design allows the acid to reach the plates quickly. It also provides for a fast interaction between the acid and the plate material. An AGM battery’s plates may be any form, making the battery’s design highly versatile. 

When opposed to conventional sealed batteries, AGM Batteries feature a lower internal electrical resistance. 

And quicker acid flow between the plates and the fibre. It also allows them to provide and accept increased rates of amperage during charging.

Gel Cell

The Gel Cell Battery features an inflexible jelly-like electrolyte in which sulfuric acid is combined with fumed silica as a bulking agent. 

The Gel Cell can be placed in any position. It’s more resistant to high temperatures and is stress and vibration resistant because of its inflexible gel-like electrolyte. 

Gel cell batteries are commonly found in electric wheelchairs, recreational vehicles, generators, and other electronic devices.

Advantages of VRLA Batteries

There are some advantages to using VRLA batteries. They are-

  • They are economical
  • These batteries have a very high capacity
  • Proper ventilation
  • Possibility of using preexisting charging gear for float charge operations at the same volt as the cells.
  • VRLA batteries offer a longer life span. This battery’s life expectancy is estimated to be approximately ten years.


Valve Regulated Lead Acid Batteries are the thing now. You’ll see them anywhere you go your car, your computer, your generator, and even the plane you fly in. 

The applications of VRLA batteries are endless. Their ability to store so much energy in such a compact space is what makes them so great. 

The safety they provide is also mentionable. Since these batteries are sealed, leakage is out of the question. Even in times of accidents. Then don’t leak so easily. 

Well, that’s about everything on VRLA batteries. Did we miss anything? If we did, let us know in the comments.