A VRLA (Valve Regulated Lead Acid) battery is a type of rechargeable battery that is sealed or maintenance-free. A lead acid battery is essentially made up of lead-acid cells connected in series inside of a single container. These cells have two lead plates submerged in a sulfuric acid electrolyte solution.

The battery converts the lead plates into lead sulfuric oxide to generate power while it is operating. The lead-sulfuric-oxide breaks down back into lead and sulfuric acid when it is recharged, reversing the previous process. This reversal, however, is incomplete and results in the discharge of hydrogen gas. In traditional lead-acid batteries, this gas would normally be released through a vent to avoid the possibility of an explosion from its buildup.

VRLA batteries, on the other hand, feature a unique design that prevents the electrolyte from freely moving within the container. This immobilizes the hydrogen close to the plates, allowing it to recombine during the recharge cycle. Consequently, throughout the recharge/discharge process, these batteries lose less water. This characteristic renders them maintenance-free as there’s no need to refill water, and they can be sealed. Therefore, VRLA batteries can be installed in any direction without fear of leakage.

However, while charging a VRLA battery, the electrolyte may boil or gas may collect too quickly. A one-way pop-off valve built into the battery manages this by opening only when internal pressure rises. The design prevents spills and leaks. These batteries are popular because they have numerous advantages over traditional lead-acid batteries.

What are the Main Types of VRLA Batteries?

VRLA batteries are primarily divided into two types: Gel Cell and Absorbed Glass Mat (AGM).

1. Gel Cell Battery:

The sulfuric acid in the electrolyte is combined with a silica additive in a gel cell battery, resulting in a thick, immobile gel-like substance. This gel composition allows the battery to be mounted in any orientation and provides increased resistance to temperature extremes, shocks, and vibrations. Gel cell batteries are frequently used in electric wheelchairs, recreational vehicles, generators, and other applications.

2. Absorbed Glass Mat (AGM) Battery:

The AGM battery is distinguished by the use of very thin fiberglass mats positioned between the plates that absorb and immobilize the acid. This design allows the acid to reach the plates immediately, allowing for a faster reaction. Because of this construction, AGM batteries can be designed with plates of varying shapes, giving them design flexibility.

Notably, AGM batteries have a very low internal electrical resistance, allowing for rapid acid movement between the fibreglass and the plates. This property allows AGM batteries to handle higher amperage rates efficiently during both discharge and charge cycles. AGM batteries are ideal for applications such as motorcycles, ATVs, and deep-cycle variants, they are commonly used as energy storage units in off-grid solar and wind power systems, as well as in large-scale robotics competitions such as FIRST and IGVC.

Also Read: Do AGM Batteries Need to be Vented?

What are the Applications of VRLA Battery?

1. AGM Battery Applications: Starting batteries for cars and other vehicles, boat ignition, RV power needs, and auxiliary equipment energy source.

2. Gel Battery Specializations: Wheelchairs and mobility scooters, marine and RV auxiliary power, and everyday heavy-use applications.

3. Deep Cycle and Renewable Energy: Marine trolling and electronics, sailboats, electric vehicles, portable devices, floor scrubbers, solar and wind energy storage, and personnel carriers.

4. Backup, Standby and Telecommunication: Uninterrupted power solutions (UPS), emergency lighting, computer data backup, power stabilization for renewable energy, and telecommunication switching operations.

5. Specialized Vehicle Applications: Motorsports, heavy-duty trucking, off-road vehicles, diesel engine initiation, light trucks, and advanced start-stop mechanisms.

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Elliot is a passionate environmentalist and blogger who has dedicated his life to spreading awareness about conservation, green energy, and renewable energy. With a background in environmental science, he has a deep understanding of the issues facing our planet and is committed to educating others on how they can make a difference.

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