What does VRLA stand for?

VRLA stands for Valve Regulated Lead Acid. VRLA batteries are maintenance free batteries and vice versa. They are one and the same.

What does SMF stand for?

SMF stands for “Sealed Maintenance Free”. SMF batteries are maintenance free batteries and vice versa. So maintenance free batteries, SMF batteries, and VRLA batteries are all one and the same.

Why are maintenance free batteries called VRLA batteries?

VRLA batteries work on the oxygen recombination principle. However, the recombination process is not 100% efficient. So over time, the internal pressure increases, and some amount of gases have to be released to maintain the ideal pressure. This is achieved with the help of one-way, pressure-sensitive valves which open when the internal pressure increases above a certain threshold and allow the excess gases to be vented. That is why these batteries are called VRLA or valve regulated lead acid batteries. Excess gases are also produced if these batteries are overcharged or discharged at rates higher than the recommended rate.

What is the basic principle of operation of maintenance free batteries?

In flooded batteries, oxygen and hydrogen are produced when the batteries discharge. These gases escape from the battery, which leads to loss of water. That is why flooded batteries have to be periodically filled with distilled water.

However, in the case of maintenance free batteries, the oxygen and hydrogen combine to form water. That is why they remain moist and don’t have to be periodically filled with distilled water.

What is the oxygen recombination principle?

Oxygen recombination principle is the main principle of operation of maintenance free batteries, and is what makes it possible to have maintenance free batteries.

In flooded batteries, oxygen and hydrogen are produced when the batteries discharge. These gases escape from the battery, which leads to loss of water. That is why flooded batteries have to be periodically filled with distilled water.

However, in maintenance free batteries, oxygen released from the +ve plate travels to the -ve plate where it combines with hydrogen to form water. It is because of this recombination that maintenance free batteries remain moist and don’t have to be periodically filled with distilled water.

Is the recombination efficiency 100%?

No, the recombination efficiency is never 100%! It is always less than 100%. But how less is what separates the good batteries from the not so good ones.

EverExceed maintenance free batteries have a recombination efficiency of more than 99% for most batteries, and in some batteries it is even higher than that. And that is the main reason for their superior performance.

If the recombination efficiency is not 100%, what happens to the gases that are emitted?

 

The gases that are emitted collect in the maintenance free batteries, which leads to a rise in the internal battery pressure. When the pressure exceeds a threshold, the one-way pressure sensitive valves open and release the gases bring the internal battery pressure back to the ideal levels.

That is why maintenance free batteries are called “valve regulated lead acid” batteries, or VRLA in short.

What are the advantages of maintenance free batteries compared to flooded batteries?

 

The advantages of maintenance free batteries compared to flooded batteries are:

  • They do not produce gases during normal operation or while charging. Therefore, they can be kept in the vicinity of any electrical equipment or any inflammable material, unlike flooded lead acid batteries.
  • They do not emit acid spray even if charged abusively. Of course, charging abusively will have an adverse effect on battery life.
  • They are spill-proof and leak-proof.
  • They can be used in vertical or horizontal position (which is something that you can’t do with flooded lead acid batteries).
    • They can be transported without any restrictions:
    1. Surface transport: Classified as non-hazardous material as per DOT-CFR Title 49 parts 171-189.
    2. Marine transport: Classified as non-hazardous material as per IMDG amendment 27.
    3. Air transport: Comply with IATA/ICAO, Special Provision A67.

What are the disadvantages of maintenance free batteries compared to flooded batteries?

 

The disadvantages of maintenance free batteries compared to flooded batteries are:

  • They cannot provide the kind of discharge currents that flooded batteries can provide.
  • They are more expensive than flooded batteries.

What are the two basic types of VRLA batteries?

The two basic types of VRLA batteries are VRLA AGM and VRLA Gel.