UPS Batteries – The True Heart of the System

The UPS system is a crucial part of your power infrastructure, and the batteries are the heart of that system. The UPS needs a battery in order to provide uninterrupted power, but the batteries are often overlooked or neglected. In the future, we will go into greater detail on each of the batteries that you can find in a UPS, and the advantages and disadvantages of each type. It should be noted that whatever battery you select, you will find that over time it will lose its ability to properly store and deliver power, so you may need a UPS replacement battery. Follow the guidelines for the maintenance, storage and usage of the batteries, though, and your battery will last longer. It still helps to keep track of your batteries and replace them appropriately.

There are three key categories of UPS battery.

  • Valve Regulated Lead Acid (VRLA)
  • Lithium-Ion batteries
  • Flooded Cell / VLA batteries

Valve Regulated Lead Acid (VRLA)

Most modern UPS systems use a VRLA battery. Valve regulated refers to the way that the battery releases gas. If the pressure in the unit gets too high, a valve will open to let out the gas until it reaches the right pressure. You cannot add water to a VRLA battery, so if the ambient temperature is too high or if there is heat generated from the battery charger then this could shorten the life of the unit.


Lithium-Ion batteries have improved a lot in recent years, and can be used for a variety of purposes. They have the advantage of being lightweight and also quite compact, and have battery management features built-in to ensure good performance in terms of charge current, voltage balance, and voltage. They adjust for over-temperature issues by disconnecting single batteries or, when necessary, a string of batteries if the temperature rises above safe levels. Battery management can send alarms to the UPS And the battery monitor, and the batteries can hold charge for a long time. This makes them ideal for UPS Applications, including ones for industrial processes that have high power requirements. They do not need to be replaced often, are affordable to run, and can operate at high temperatures too, so for mission-critical applications they can be a popular low-cost choice.

Flooded, or Wet Cell

Wet Cell, VLA or Flooded Cell batteries, as they are often known, are incredibly reliable and can have a useful life of up to 20 years. These batteries are made of thick plates that contain lead, compartments flooded with electrolyte acid. Because of the acid, there are some safety considerations with these batteries, and they need to be stored in a separate battery room. They are also quite expensive, but the long life makes them a popular choice for specialist applications.

It is important to think carefully about your UPS requirements and how you manage your batteries to get the best performance out of your machine.