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The Various UPS Battery Backup Technologies

There are three battery design technologies generally used in UPS systems.
They include:

  1. Lead-Acid, which is by far the best cost-effective solution. They are low maintenance, easily disposed of, and the most popular choice.
  2. Nickel Cadmium.
  3. Lithium Ion or LiFePHO4.

All 3 of these technologies work very well and reliably with a Riello UPS unit from Standby systems.

  1. Lead Acid batteries

Lead-acid batteries are well known and extensively used for all types of battery applications from Standby to Automotive and many other uses. Apart from being heavy by comparison, they are by far the most cost-effective battery solution for use in a UPS system.

There are two main types of lead-acid batteries used in a UPS:

  • Vented lead-acid
  • Sealed lead-acid (SLA) or valve regulated (VRLA) to be more precise

Vented Lead-acid

Vented lead-acid batteries have a 15-to-20-year design life. They are available in Flat plate, Tubular, or Plante design. The most popular makes used in South Africa are Exide and Chloride brands that Standby Systems procures locally from the manufacturer First National Batteries. These products are 100% manufactured in the East London plant of First National Batteries and are available from 9AH up to 4450AH.

They are filled with free-flowing electrolyte (Diluted Acid) solution and have caps on top. These caps can be removed to top up the electrolyte levels due to water loss when in use. If they fall over or crack, they will leak large amounts of toxic and highly corrosive acid into the environment.

Generally, only used in very high-power UPS applications, these batteries need to be housed on open stills at floor level in a specially designed and ventilated battery room with proper extraction to remove the large amounts of Hydrogen they generate when they are charging or discharging.

Being a high maintenance product that requires weekly, monthly, and three-monthly checks and top-ups, they are not really suitable for use in commercial buildings and data centers where space is a problem and where safety due to the high H2 generation is an issue.

Sealed Lead Acid

The name is deceiving as no SLA battery is really 100% sealed. They are fitted with a safety valve, and the correct term is Valve Regulated Lead-acid battery or VRLA. The battery’s electrolyte (Acid solution) is held between the plates making up the cells by a glass mat called an AGM (absorbent glass mat)—this is what is known as a starved electrolyte battery. This matt absorbs all the electrolytes so that no electrolyte is free running. As there is no free running electrolyte, it is referred to as a starved electrolyte battery product.

Any battery that charges or discharges will generate gasses that, if not controlled in a sealed environment, will cause the battery to explode. By “sealing” the battery, the gas is forced to recombine with the electrolyte of a VRLA battery, with pressure build-up acting like a ‘catalyst’ to force the gas back into liquid.

However, a small amount of electrolyte gas will never recombine with the liquid. This is known as recombination efficiency. It varies from manufacturer to manufacturer and is why it is very important to use well-known battery brands like ELITE, UPSEL, CSB, ENERSYS, and GENESYS, which have very high recombination efficiencies ensuring maximum battery service life for your UPS. The gas build-up will eventually be too much if the battery were completely sealed, so a pressure valve in the lid of the battery will purge the gas that doesn’t recombine.

Generally speaking, UPS systems need a high-rate battery, so an AGM type product is used. Another type of sealed battery technology is GEL technology, where the electrolyte is normally in a ‘jelly’ type condition. This kind of battery performs better when used in long deep discharge applications, particularly in telecoms, where it is more widely used than the AGM product.

It is a known fact that a UPS battery will not last forever. A battery is a component that has a life expectancy that is even further shortened by various factors such as temperature, maintenance, the number of discharges, etc.

Sealed lead-acid batteries have a service life expectancy of 3 years or 6 to 10 years, but there are no guarantees. All these batteries are covered by a 12-month warranty against manufacturer’s defects from the date of delivery.

See more about our battery ranges.

  1. Nickel Cadmium

Nickel Cadmium batteries are widely used in telecoms industries and in the UAE due to their resistance to high temperatures and cycling ability. They boast a life expectancy of 20 years. Instead of the battery using an acidic electrolyte, it uses an alkaline electrolyte in the form of Potassium Hydroxide. The positive plate consists of Nickel hydroxide and the negative plates of Cadmium hydroxide.

This type of battery technology is, however, very expensive and requires high maintenance. It is not a very common battery to be used in UPS systems nowadays, with the sealed lead-acid being far easier to obtain at low costs with lower maintenance.

Nickel Cadmium batteries are very difficult and expensive to dispose of at end of life. There are no safe disposal sites in South Africa for this product, making its use in UPS technology undesirable.

  1. Lithium Batteries

This type of battery technology has been successfully used in many devices such as portable power tools, laptops, and cell phones for many years now. In recent years, it has increasingly been used in powering electric vehicles where it has excellent cycling properties, which are needed in EVs. It has a very low weight when compared to other battery technologies.

Lithium batteries need an electronic circuit – often called a BMS – built into them to control the battery. Without the BMS, the battery will most often catch fire which has been a problem in some cases during its development.

Lithium batteries have excellent cycling abilities making them most suitable for use in solar environments. Unfortunately, they don’t have much to offer a UPS backup battery scenario and come at a huge expense.

As with Nickel-Cadmium technology batteries, Lithium battery products currently cannot be recycled in South Africa and, therefore, are considered a huge environmental risk with land and water pollution via landfill dumping at end of life—a big problem in SA.

If you have any questions, please contact Standby Systems technical and sales support on 011 794 2541/ 011 794 3406 / 082 450 2361 or email our sales or service departments. Visit Standby Systems or Riello UPS for more information.

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