What is a UPS Battery: Definition, Types & Technical Specifications

An Uninterruptible Power Supply (UPS) system is vital to run critical functions uninterrupted during a power failure. These devices are common in commercial and residential establishments. The main powerhouse of a UPS is its battery.

A basic understanding of a UPS battery can be useful when buying one. In fact, the batteries are the major cost of a UPS system.

However, many aspects of UPS batteries can be confusing. Therefore, this article will provide all the details regarding UPS batteries.

What is a UPS Battery?

What is a UPS Battery?

An Uninterruptible Power Supply (UPS) battery is a device that stores power inside an Uninterruptible Power Supply system. UPS is designed to charge and store electricity when the system is connected to the grid. Once the grid electricity goes down, the UPS then releases the stored electricity. The storage and discharge of electricity are done in the battery.

What is a UPS Battery Used For?

The UPS battery is designed to provide power for a short duration to critical systems. This is mainly done to combat electrical failure in the grid. These critical systems usually have a backup power system to run them for a prolonged time. The UPS system is designed to fill the transition gap from the electrical grid to backup power and vice versa. This transition can take anywhere from a few seconds to several minutes.

Without a UPS, all electrical systems will go offline in case of power failure. The systems return online when the generator or alternative backup power is turned on. Switching to the backup power can take anywhere from a few seconds to a few minutes. In settings like hospitals, these few seconds can be critical to life. In other settings like banks, data centres, and organisations, the loss of power can mean data losses. A UPS ensures none of these happens by powering the critical functions during the transition gap interval.

What is a UPS Battery Not Supposed to Do?

A UPS battery is not designed to provide prolonged power to the system. Prolonged power backup power is derived from a generator or a similar secondary power source. A UPS should only fix the power gap between the electrical grid and generator backup transitions.

Functions of a UPS Battery System

Besides filling the transition gap, an Uninterruptible Power Supply also fulfils several other functions. Some of the uses of a UPS system are:

Power Surges

Power surges are dangerous to electronics. Even small power surges can fry the internal electronics of any device. A UPS system absorbs power surges by inbuilt circuit mechanisms.

Voltage Regulation

Modern UPS batteries act as voltage regulators for the connected equipment. Voltage fluctuations are common in every electrical grid. UPS system provides constant voltage even during dips in the grid voltage.

Unstable Power Supply

A UPS system is a convenient option for handling an unstable power supply. Switching to a generator repeatedly is inconvenient during short periods of power instability. A UPS system handles these issues well without switching to generator power. It automatically charges the internal battery during the mini-cycles of power stability.

Remote Management

Modern UPS systems can display all connected equipment’s voltage and current draw. This provides remote management of power when required. It also gives greater control over where a user wants to spend the backup power.

Power Factor Correction

Power Factor Correction is a useful feature of modern UPS systems. It helps in saving the total power consumed by electrical equipment connected to the UPS. A UPS system provides Power Factor correction by producing reactive power internally.

Energy Storage

A UPS system stores only the excess energy of the grid. This energy is provided during periods of energy deficit. This provides a very efficient energy management for the grid.

What are the Parts of a UPS Battery?

What are the Parts of a UPS Battery?

The UPS battery is the heart of an Uninterruptible Power Supply. The battery has various components that work together to make its operation possible. These components are:

Battery Cells

A single UPS battery consists of multiple battery cells connected in series. For instance, a 12 V battery can have four to six cells. Each cell has a nominal voltage in the range of 2 V to 4 V. The series connection creates the total voltage compatible with the system, such as 12 V, 24 V, etc.

All the battery cells in a single UPS battery should have the same chemistry. Additionally, since the battery is connected in series, a fault in one cell will lead to battery failure. Therefore, battery maintenance is important to keep all the cells in optimal condition.

UPS systems require a high number of battery cells to meet the power demands of large systems. For instance, a 12 V DC system can require as many as 60 valve regulated lead acid battery cells.

Battery Enclosure

Battery enclosure is the box that stores the UPS batteries safely. Small UPS systems can have the battery housed inside the system. However, most setups require medium to large UPS systems. Therefore, the batteries are stored outside the UPS housing.

Good battery enclosures protect the batteries from the elements of nature. Additionally, they provide thermal insulation to the battery, which is important for optimal battery health.

Battery Management System (BMS)

Battery Management System (BMS) automatically monitors the functions of UPS batteries. BMS ensures that the battery doesn’t go out of the safe zone during charging or discharging. A UPS system can have a large number of batteries. Constantly monitoring these batteries manually is not an easy task. Therefore, a BMS is a must-have for a UPS system.

A good BMS will prolong the life of a UPS battery significantly. Additionally, it can provide vital battery information to a display connected to the BMS. Many BMS also have features for remote monitoring.


The UPS inverter converts the battery’s DC electricity into AC electricity. The AC electricity is then fed to the appliances and sockets in the system. An inverter is a crucial part of all UPS batteries. UPS batteries, like any other battery, store and release DC current. However, appliances like desktops run on AC electricity. Therefore, the inverter does the job of changing battery DC to appliance-supported AC.


The charger provides power to the UPS battery during periods of stable electricity. The UPS stores the excess power after the system uses a sufficient amount. Every battery comes with a recommended charging option. It is always recommended to use the battery charger that the battery manufacturer recommends.

Transfer Switch

Most UPS batteries come with an Automatic Transfer Switch (ATS). ATS switches the load between the grid, the UPS, and the generator battery backup. During power failure, the ATS switches the generator and waits for it to get ready. Meanwhile, the UPS battery backup provides power to the system. Once the generator is ready, the ATS transfers the load to the generator power. The ATS restores power to the grid when the electricity is restored.

Monitoring Software

Modern UPS batteries come with a dedicated monitoring software. The monitoring software provides a remote overview of the important UPS parameters. Parameters like voltage, current, and State of Charge inform the user about the health of the UPS system. Therefore, monitoring software ensures 24×7 system availability of UPS batteries.

Different Types of UPS Batteries

A UPS battery has multiple options in terms of battery chemistry. Different battery chemistries have their own benefits, shortcomings, and particular usage. Let us study the different types of UPS battery chemistries to learn what they can offer to you:

Flooded Lead Acid Batteries

A flooded lead acid battery is also simplified as a lead acid battery. It contains two lead electrolyte plates dipped in an electrolyte solution. These are the most primitive type of UPS batteries. The internal chemical reactions of the battery lead to the release of toxic gases. Additionally, it requires frequent electrolyte top-ups.

Flooded lead acid batteries are the least preferred option among all the different options. This is due to their significantly lower lifespan, low depth of discharge, poor operating range, and poor safety. However, they are still in use today due to the cheap cost.

Valve Regulated Lead Acid (VRLA) Batteries

VRLA batteries have a sealed design to eliminate electrolyte spills and top-up requirements. They have two different types- gel batteries and AGM batteries. Gel batteries have the electrolyte absorbed in a silica gel. Absorbed Glass Mat (AGM) batteries have a glass mat separating the two electrodes. The electrolyte is absorbed in this glass mat.

VRLA batteries are a significant improvement over the Flooded Lead Acid battery design. However, they still suffer the shortcomings for poor depth of discharge and lower lifespan.

Lithium-ion Batteries

A lithium-ion battery contains a lithium-based electrode and a graphite electrode. These batteries are a significant improvement over lead-based options. Therefore, they have replaced flooded and VRLA batteries in most UPS applications.

Lithium-ion batteries have a longer lifespan and a higher Depth of Discharge. This means you can use the battery for longer in each cycle. Additionally, the battery lasts for a higher number of cycles.

There are many different material options for the lithium-based electrode. Due to this, lithium batteries come in many different types. A lithium Iron Phosphate (LiFePO4) battery is the best option among all these types due to its more than ten-year lifespan, higher depth of discharge, and many other benefits.

Which is the Best UPS Battery?

LiFePO4 is often considered to be the best UPS battery. These batteries cost more than the lead acid options. However, they are a significantly better option regarding value for money. While lead acid batteries can show signs of the end after two years, LFP batteries easily last five times longer.

Additionally, lead acid batteries only have a 50% depth of discharge. This means that a 100 Ah battery will only provide 50 Ah energy. However, LFP batteries have a 100% Depth of Discharge. Therefore, a 100 Ah battery will provide complete 100 Ah power.

What are the Advantages of a UPS?

What are the Advantages of a UPS?

UPS is indispensable when it comes to powering critical functions. Some of the benefits of UPS are:

  • Power Backup: The primary benefit of UPS is that it doesn’t cut off electricity to the system during power failure. Switching to backup power takes some time. UPS battery backup is the lifesaver for those few seconds or minutes.
  • Protection Measures: UPS battery backup has several protective measures to guard the critical components against power surges, voltage fluctuations, and other electrical hazards.
  • Automatic Shutdown: UPS systems can automatically shut down if a prolonged power outage occurs. This gives users sufficient time to plan. Users like data centres can safely save their data in such occurrences.
  • Increased Equipment Lifespan: Frequent power failure degrades the life of all electrical components. UPS provides a safe way to turn the appliances off without any abruptness. This increases the life of the equipment considerably.
  • No Downtime: A UPS provides the facility for a system to run 24×7 without any downtime. In cases like IT infrastructure, this saves a lot of costs and customer complaints.
  • Remote Monitoring: UPS battery backup has the feature of remote monitoring. You can view all the system’s electrical consumption parameters without having to check on the individual appliances or batteries.
  • Eco-Friendly: UPS battery backup only saves the excess energy of the electrical grid. Therefore, it is a green energy option. Unlike generators, it does not consume fossil fuels to provide power.

What are the Disadvantages of a UPS?

What are the Disadvantages of a UPS?

While UPS battery backup is crucial to every critical system, it can also have certain disadvantages. Some of the limitations of a UPS battery backup are:

  • Investment: UPS battery backup can be a costly investment. This is especially true for systems that have huge loads to back up.
  • Maintenance: Every UPS battery requires some form of periodic maintenance. However, this limitation can be avoided by choosing a less maintenance LFP battery option.
  • Limited Backup: UPS batteries can only provide backup for the transition time between the grid and the backup generator. It cannot provide power for a prolonged period.
  • Load Limitations: UPS battery backup is designed for particular loads. Connecting appliances with higher loads can trip the system.
  • Overheating: UPS battery backup is prone to overheating, especially during charging.

How Long Do UPS Batteries Last?

A UPS battery can last anywhere from three to fifteen years. The battery’s lifespan varies depending on the type of battery you choose. Lead-based options have significantly lower lifespans. On the other hand, lithium-ion batteries last the longest. An important thing to note is that the battery requires proper maintenance to fulfil its lifespan optimally.

What Maintenance is Required for UPS Batteries?

What Maintenance is Required for UPS Batteries?

Common maintenance for all UPS batteries is lubricating the terminals and ensuring there is no corrosion. The exact maintenance steps can vary based on the type of battery chemistry. For flooded lead acid batteries, maintenance can include filling the electrolyte solution. For VRLA batteries, maintenance can include the release of buildup gases. Lithium-ion batteries only need general maintenance, like terminal checks.

How to Maintain a UPS Battery For a Longer Life?

UPS battery maintenance is easy with a proper checklist. Here are some maintenance tips that can help in a healthy battery with a significantly longer lifespan:

  • Ensure that the battery stays within a safe state of charge. Overcharging or over-discharging the battery can damage it permanently. The safe state of charge is listed with the battery by the manufacturer.
  • Clean the battery terminals regularly. Ensure that there is no dust or rust on the terminals. Dirty or corroded terminals can lead to an underperforming battery.
  • The battery enclosure should always have proper ventilation. Ventilation helps maintain a safe operating temperature for the battery and avoids overheating.
  • Visually inspect the battery for any physical damage. A damaged battery often shows signs of cracks, bulging, fluid leaks, or a pungent smell.
  • Ensure that the UPS battery is compatible with the connected load. Overloading the batteries can be detrimental to their health.
  • If any battery shows signs of damage, replace it quickly. Replacement is a safer option for the appliances and the battery environment.

Troubleshooting Common UPS Battery Problems


Troubleshooting Common UPS Battery Problems

Uninterruptible Power Supply can sometimes face problems like all electrical devices. The problem is usually battery related. Here are some of the issues you can face and ways to solve them:


Overloading is a common issue with UPS batteries. Overloading occurs when the load connected to the battery exceeds battery capacity. To fix overloading issues, reduce the load immediately. You can also increase the capacity of your UPS battery.


Overheating of UPS batteries usually occurs during charging. To prevent overheating, ensure that the batteries are not getting overcharged. Also use a ventilated enclosure for the battery strings.


Corrosion of battery terminals occurs due to high humidity. Corrosion can be avoided by keeping the UPS battery in dry conditions. In addition, clean the terminals of the battery of dust and grime regularly.

Charging Issues

Charging issues are usually the result of a faulty charger. If the charger works correctly, it can result from aged and damaged batteries. It requires battery replacement.

Manufacturing Defects

If a new battery has any form of manufacturing defect, it is usually covered in the battery warranty. Contact the manufacturer and discuss the defects in the battery with them. Eco Tree Lithium has a warranty period of 6 years to solve such issues.

Damaged Batteries

Common indications of a damaged battery are a swollen case, leakage, or a pungent smell from the battery. These issues are not fixable, and battery replacement is required.

How Often Do You Need to Replace a UPS Battery?

You may need to replace the UPS battery anywhere after 3 to 10 years. Lead batteries only last for a few years before requiring replacement. Lithium batteries last longer. LFP batteries last over 10 years.

What happens if you don’t replace a UPS Battery?

Not replacing the UPS batteries on time can lead to losing emergency power. The UPS will fail to perform its designated job. Damaged batteries can also leak, which will corrode the nearby environment.

Can I replace the UPS battery with a car battery?

No, you cannot replace a UPS battery with a car battery. Car batteries are starting batteries. They provide a high surge of current in a very short duration. However, the UPS battery provides a moderate current for a longer duration.

How to Choose a UPS Battery?

How to Choose a UPS Battery?

Here is a list of important factors that are vital to consider when choosing a UPS battery:

  • Capacity: Battery capacity should fulfill the load connected to the UPS. Choose a battery with 30% excess capacity than your system load.
  • Runtime: Batteries come with an Amp hour rating, so you can know how long it will power your load. Ensure that your battery can provide sufficient power to cover the transition to an alternative power supply generator.
  • Battery Type: As mentioned earlier, different battery chemistry brings their benefits and limitations to the table. Choose the battery chemistry that meets your requirements.
  • Battery Warranty: The warranty is important to know how long the battery will last. A battery with a six-month warranty will hardly last for a couple of years. Eco Tree Lithium’s six-year warranty batteries are expected to last for around 15 years.
  • Brand: Choosing a reliable brand ensures that your battery doesn’t face any issues unexpectedly. Good brands cover any issues in their warranty period. This provides a better return on investment.

Where to Buy a UPS Battery?

Eco Tree Lithium is one of the leading manufacturers of premium UPS batteries. The LFP batteries at Eco Tree Lithium are made with the highest quality standards. Every battery comes with an intelligent Battery Management System for remote monitoring. Additionally, multi-layered security measures protect against surges, short circuits, or any voltage fluctuations.

What is the Difference Between a UPS Battery and a Normal Battery?

UPS batteries are an advanced version of a normal battery. UPS batteries are designed to be highly reactive to external power. This triggers the UPS battery in a microsecond during a power failure. The highly reactive nature also enables UPS batteries to provide features like absorbing surges.

Therefore, a UPS battery has the ability to filter power. This results in consistent power to the appliances throughout the operation. However, an ordinary battery is not designed to be highly reactive. Therefore, a normal battery can take a second to switch during a power failure. Additionally, it will not provide features such as surge protection.

Is There a Difference Between UPS Battery and a Battery Backup?

Is There a Difference Between UPS Battery and a Battery Backup?

The UPS system and battery backup refer to the same device that provides electricity during an outage. However, there are fine differences between the usage of the two. The differences don’t show in their structure or working process. The differences are present in the way these two battery options are used.

UPS batteries are higher-capacity equipment that are designed to run entire ecosystems. It could be hospitals, data centres, or a complete office. UPS systems have a hi-tech monitoring system that regulates all the battery parameters. In addition, the battery has several protection measures against surges, voltage fluctuations, and other hazards.

On the other hand, battery backup is designed for an isolated system or a small group of systems. It is a very simple setup with a limited amount of electrical capacity. Usually, it can only power devices such as a single desktop or a router.


Choosing the right UPS battery eliminates your worries for several years to come. On the other hand, any wrong decisions can lead to loss of investment and even damage to the connected equipment.