What Are UPS Battery Failure Symptoms? – DIY Appliance Repairs, Home Repair Tips and Tricks (2023)

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UPS batteries are crucial backups during power outages. Unfortunately, many users find that their batteries fail when they need them the most. So what symptoms should you look for to know when to replace your UPS battery?

The first symptom of UPS battery failure is age. A battery approaching the later stages of its lifespan is more likely not to work effectively. Repetitive alarm sounds and lights and slow charging or fast discharging hint that the battery will fail. Lastly, look out for swelling and smells.

UPS batteries show several failure symptoms that you should be aware of. This guide will walk you through 8 of those symptoms so you can preemptively change the battery as needed.

What Are Common Symptoms Of A Failing UPS Battery?

A UPS battery is an excellent way to keep your devices running during a power outage. However, a failed UPS will be useless to you in an emergency.

That’s why it’s crucial that you can tell when a UPS battery needs to be replaced. Some signs are more subtle than others,

Here are 8 signs your UPS battery is failing or will fail soon:

#1 End of Battery Lifespan

What Are UPS Battery Failure Symptoms? – DIY Appliance Repairs, Home Repair Tips and Tricks (1)

Its lifespan is the first sign that your UPS battery will soon experience failure.

Ask yourself these 2 crucial questions:

  • First, how long is the UPS battery supposed to last?
  • How long have you been using that unit?

To put it simply, the closer your UPS battery is to the end of its lifespan, the more likely it’ll experience one or more of the other symptoms on this list.

UPS batteries typically last between 3-5 years. However, that average lifespan can differ significantly between brands and models.

For instance, a lower quality model could fail sooner, while a more robust model could last longer.

To be sure, please refer to the user manual to understand the manufacturer’s expectations of how long your UPS battery should last.

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Read: How To Reset Dyson Vacuum?

#2 Repetitive Alarms

UPS units these days have built-in alarms to alert you of any problems. For instance, many come with overheating alarms that warn you when the battery reaches dangerous temperatures.

Those alarms should only activate when a real problem occurs. However, another sign that your UPS is failing is when its alarms activate repetitively.

For instance, you’ll find that a failing UPS battery will trigger one or more of its alarms repeatedly, even when nothing is wrong.

#3 Flashing Panel Lights

What Are UPS Battery Failure Symptoms? – DIY Appliance Repairs, Home Repair Tips and Tricks (2)

Aside from repetitive alarms, another common sign of UPS battery failure is when the panel lights flash continuously for no reason. These flashing lights may or may not be accompanied by the repetitive alarms mentioned above in #2.

At first glance, this and other symptoms listed here might make it seem like the entire UPS unit has failed. However, the fault is likely only with the batteries inside that have become worn out, not the other UPS components.

Read: Why Roomba Won’t Start Cleaning? – Troubleshooting Guide

#4 Charging Too Slow

Next, you might notice that your UPS battery takes much longer to charge after draining all its stored energy.

As the battery ages, the unit’s chemical reactions will change for the worse and become inefficient. In addition, those changes make it much more challenging for the battery to receive and store electrical power.

Again, this process will differ between UPS battery brands and models. So, you’ll have to refer to the user manual to know how fast the battery is supposed to charge to its maximum capacity under normal conditions.

When the battery gets older and the charging process takes a lot longer than average, that’s a sign your battery isn’t performing well anymore. The risk of battery failure is high and will continue increasing with time.

#5 Discharging Too Fast

This symptom of UPS battery failure is closely related to what you saw earlier in #4.

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Remember: as your UPS battery gets older, the chemical reactions that allow it to function will become increasingly inefficient.

In symptom #4 earlier, you saw that the failing battery takes too long to charge. On top of that, a failing battery will also discharge what little energy it stores much faster than usual.

So, if there’s ever a power outage and you need the UPS to keep your devices running, the battery will not last as long as you’d hope.

Read: Roomba Keeps Saying Clean Debris Extractors – Troubleshooting Guide

#6 Swollen Batteries

What Are UPS Battery Failure Symptoms? – DIY Appliance Repairs, Home Repair Tips and Tricks (3)

Failing UPS batteries also demonstrate physical symptoms that you can look for. An example of that is swelling in the battery units.

The swelling can get bad enough that the battery presses outwards against the casing. For units with more than one battery, the swelling can also cause them to press against each other.

You must understand that swollen batteries are harmful. So, if you notice any swelling on your UPS battery, you should stop using it immediately.

The swelling happens as a result of there being too much electrical current flowing inside the battery. That then leads to a dangerous buildup of gas and heat inside the battery.

Read: Do Roomba Batteries Need To Be Replaced?

#7 Low Voltage Tests

Sometimes, the symptoms of a failing UPS battery can be hard to notice. That’s especially true if there are no physical signs like swelling in the battery or repetitive alarms from the UPS unit.

Another way to know if your UPS battery is failing is by testing it with a multimeter. Your UPS battery should maintain its voltage within a specific range if it’s in excellent working order.

What Are UPS Battery Failure Symptoms? – DIY Appliance Repairs, Home Repair Tips and Tricks (4)

However, if the voltage drops below that range, the battery isn’t as healthy as it should be. The battery will continue to function, but it likely won’t help you much when there’s a power outage.

A typical voltage for UPS batteries is anywhere between 2.25 volts to 13.5 volts. Again, the best reference to see what applies to your UPS battery brand and model is the user manual. So, be sure to check that document for more information.

#8 Burning Or Other Smells

Lastly, you should be wary of any unusual smells like burning that come from your UPS battery. A standard UPS battery that’s functioning correctly should not give off any smell at all.

However, unusual smells could be the result of an overheating battery. So when you notice the smell, shut off the battery immediately and do not continue using it.

Read: Roomba Vacuum Cleaner Troubleshooting Guide

Frequently Asked Questions (FAQs)

Understanding your UPS battery’s functions will help you get the most value out of it. So, here are a few more questions and answers you’ll find helpful.

What Happens When A UPS Battery Dies?

When a UPS battery dies, it won’t be able to keep your devices running during a power outage. In other words, the UPS battery will not be helpful to you when you need it the most.

What Causes A UPS Battery To Fail?

UPS batteries typically fail due to excessive wear and tear from old age. Besides that, extremely hot or cold temperatures and a lack of ventilation can cause the UPS battery to stop functioning correctly.

What Is The Average Life Of A UPS Battery?

A UPS battery can last for an average of 3 to 5 years. However, the lifespan will be different depending on the quality of your UPS battery brand and model. Higher-quality batteries can last longer, especially if you store and maintain the battery correctly.

When Should I Replace My UPS Battery?

It’s best to replace your UPS battery when it gets old, and its performance deteriorates. Some UPS units will have alarms informing you that you should replace the battery. In doing so, you can ensure the UPS battery works effectively during a power outage.

How Do You Test A UPS Battery?

You can test a UPS battery by removing it and checking it with a multimeter. The multimeter allows you to test the battery’s voltage and assess the battery’s health.


What are the signs of failing UPS? ›

  • 10 Signs It's Time for a UPS Battery Replacement. ...
  • It's been 3 to 5 years since the purchase date. ...
  • The UPS is beeping or displaying caution lights. ...
  • The battery life is shorter than advertised. ...
  • You notice the chassis bulging or other chassis damage. ...
  • Systems go offline during a power outage.

What happens when a UPS battery fails? ›

Typically, repeating alarms, flashing panel lights, and strange terminal displays are all symptoms of a failing UPS battery.

What causes UPS battery failure? ›

The most common reason for UPS battery failure is incorrect temperature or temperature variances. Optimum performance and the manufacturer's average stated life is achieved if the lead acid battery temperature is maintained at between 22-25 ºC.

What is a UPS failure? ›

UPS failure is a leading cause of unplanned power outages in data centers. It results in costly downtime service and disrupts the overall operation of data centers. Batteries are the major culprit of UPS failure. Every UPS system has a set of batteries. One battery failure can lead to the failure of the entire set.

How do you test if a UPS is working properly? ›

Simply unplugging the UPS backup from its power will provide a very immediate test of its ability to function. This is when many units will start beeping, once they "realize" the battery cannot maintain its output when disconnected from the main power source.

How do I check my UPS battery health? ›

External battery testing should form part of a planned preventive UPS maintenance regime, although it can also be provided as a standalone service.
  1. Impedance Testing. ...
  2. Electro-Chemical Testing. ...
  3. Load Bank Testing (Discharge Testing) ...
  4. Partial Discharge Testing. ...
  5. UPS Battery Monitoring. ...
  6. Further Reading:

Can a UPS still work without battery? ›

For offline and line interactive, most of them are designed to stop working when they find out the battery is abnormal. On the other hand, online UPS usually is designed to run even without battery. Offline UPS does not provide any feature without battery.

How do you solve UPS problems? ›

UPS is not working properly
  1. Be sure the UPS batteries are charged to the proper level for operation. ...
  2. Be sure the UPS power switch is in the On position. ...
  3. Be sure the UPS software is updated to the latest version. ...
  4. Be sure the power cord is the correct type for the UPS and the country in which the server is located.

What happens if you don't replace UPS battery? ›

UPS systems typically have a SERIES connected battery system to provide a high current to the UPS System DC Bus. If one cell in a string opens, it will break the current in the entire string. In short, just one failed battery cell can bring down your entire infrastructure.

What are the three main causes of battery failure? ›

What causes battery failure?
  • The battery is not being used in the application for which it was designed.
  • The battery is not sized properly for the application.
  • The vehicle has excessive electrical accessories.
  • The battery is not properly fitted into the vehicle.
  • The battery cables are not clean.

What problems can a dead battery cause? ›

Internal components: A weak battery affects performance by causing damage to the engine's internal parts. The low voltage causes the temperature to go up, and overheating can result, which causes damage to the engine parts.

How do I reset my UPS? ›

Turn off the UPS: press and hold the On/Off button until the UPS beeps, then release the button. Disconnect the UPS from the AC outlet. 3. Reconnect the UPS to a functioning AC outlet.

How do I know if my UPS battery is low? ›

All UPS batteries have this alarm, and when they run a self-test, if the battery is low, it will either make a sound or you'll notice a light going off. Either/both are indicators that the battery needs to be replaced.

How long can a UPS last without power? ›

For most typical computer workstations, one might have a UPS that was rated to keep the machine alive through a 15 minute power loss. If it is important for a machine to survive hours without power, one should probably look at a more robust power backup solution that includes a generator and other components.

What does red light in UPS mean? ›

A red light on your UPS typically indicates that a critical failure has occurred and your system is not working to meet its function and your needs. You should seek advice from your supplier and manufacturer.

How often do you need to replace a UPS battery? ›

Typical UPS battery life is 3 to 5 years. This is dependent on a number of factors, including: Temperature where the unit is located.

What happens if you overload a UPS? ›

When loads exceed the UPS's rated VA(volt-amp) or Watt capacity, the overload LED will illuminate and the UPS will emit a continuous tone. The alarm stays on until the overload is removed. Resolution: Disconnect nonessential load equipment from the UPS to eliminate the overload.

How do you revive a UPS battery? ›

Carefully open the filler caps of the battery. When the prepared solution of Epsom salt and distilled water is cooled to room temperature, pour this solution into each filler hole. Add an equal amount of solution into all filler holes. Replace the filler caps and shake the battery.

How do I clean my UPS battery? ›

Using around a teaspoon of baking soda, or more as necessary, coat your battery terminals and other affected areas. Pour a small amount of water on each terminal then use your brush to scrub the corrosion away. While a steel wire brush will work the best, an old toothbrush can work with enough elbow grease.

Do UPS batteries drain when not in use? ›

The type of battery used in all UPS products has a "self-discharge" characteristic. This is the amount of charge the battery will naturally lose even if it is disconnected. At 20° Celsius, a battery will lose 3% of its capacity per month.

Does a UPS have a fuse? ›

To meet UL safety standards, a UPS needs basic overcurrent protection to prevent fires, which is usually handled by a fuse on the ac input.

Can you run a TV off a UPS? ›

You can power a TV with an Uninterrupted Power Supply (UPS), and depending on the size (and cost) of the power supply it may keep the TV going for anywhere from 15 minutes to 2 hours. It's smart to use a UPS for your TV (or other expensive electrical equipment) as cost-effective insurance.

How do you charge a UPS with a dead battery? ›

To recharge the battery, simply leave the UPS plugged into an AC outlet. For all UPS models except the version with IEC outlets: connect the power cord(s) of your computer equipment to the output receptacle(s) of the UPS.

What causes UPS overload? ›

Like the error message says, the overload is caused by too much equipment plugged into the battery backup outlets, or too much power is being pulled by the devices. Certain devices can have a high inrush current, so when they start up or run they pull a large amounts of power and it can cause an overload.

Can a UPS trip a breaker? ›

The circuit breaker will ""trip"" or pop out if there is a severe overload on the output side of the UPS (i.e., too much equipment is plugged into the UPS).

Is it worth replacing batteries in UPS? ›

Therefore, if batteries are approaching the end of their useful life, and the UPS still has years of life remaining, replacing your batteries makes sense from a return on investment (ROI) standpoint, as well as to avoid unexpected and costly downtime.

Should I replace my UPS battery or buy a new one? ›

The costs to replace a string of batteries can be very expensive (sometimes 40% of the value of a new UPS system). While replacing an entire UPS system can be costly, it will provide fresh batteries, new features, higher efficiency, and a warranty.

What are 2 common issues of battery failure? ›

Corrosion or damage to the positive and negative terminals. Broken internal connections as a result of corrosion. Broken plates due to corrosion and vibration. Damage to the battery case.

How do you diagnose battery issues? ›

To get a good sense if your battery is the cause of your issues, test the voltage using a multimeter. Put the black multimeter lead on the negative battery cable and the red lead on the positive cable. If the reading is 12.45 volts or greater, your battery has a good charge.

How can you prevent battery failure? ›

Here are some things you can do to save your car battery when your car is not in use.
  1. 1) Use a trickle charger or battery conditioner. ...
  2. 2) Avoid turning your car on and then off again. ...
  3. 3) Avoid short journeys. ...
  4. 4) Drive your car for 15-20 minutes at a time. ...
  5. 5) Alternate trips if your household has more than one vehicle.

Can a bad battery cause electrical problems? ›

Can a Bad Battery Cause Electrical Problems? Yes, if your battery is underperforming it can cause systems within the vehicle to malfunction. A bad battery can also result in air conditioners, stereos and other applications not receiving enough power to function properly.

Can a dead battery revive itself? ›

Simply put, no car battery, whether healthy or dead, can charge itself. It always requires an external power source to get charged. Can Dead Batteries be Charged? Once a car battery is dead, the alternator will fail to recharge it completely.

Can a dead battery be brought back to life? ›

Use Epsom Salt Solution

If the problem is caused by a low electrolyte level, using Epsom salt (magnesium sulfate) to make an electrolyte solution will help revive your car battery. Check out this article on how to check your battery's electrolyte level.

Is there a reset button on a UPS? ›

The UPS will reset itself after a power outage. At this point there will be beeping and the UPS will be in bypass mode. o Go to the back and flip the switch to “Utility” o On the front of the UPS hold the OFF button for a second until it beeps. This will shut off the beeping and the UPS.

How long is UPS battery life? ›

All you need to know are a few parameters and you are good to go. The UPS backup time depends on the power consumption of the UPS, the power of the load, and the battery capacity. In general, you can expect your inverter battery to last anywhere around 5 to 10 hours when it is fully charged.

Is UPS charging when turned off? ›

The UPS will charge the battery whether the unit is turned on or turned off. Please contact our Tech Support department with installation, troubleshooting, or general product questions.

Why does my UPS switch off when the power goes out but works when I unplug it from the wall? ›

It seems possible that your backup power unit is not a real UPS and the power flicker was shorter than the transition time (milliseconds) for the backup power unit to transfer to battery. You may need to get a true UPS.

When should you replace a UPS? ›

But, with proper servicing, a UPS can operate safely and reliably. If it's under 12 years old, you probably have a little life left. If it's over 12 years old, it may be time to replace the system.

How long should a UPS last for? ›

Because their chemicals naturally deplete over time, even UPS batteries that are well cared for and properly maintained will still need to be periodically replaced, generally every three to five years.

What is the average lifespan of a UPS? ›

What is the Lifespan of a UPS Battery? There are a few different factors that can contribute to the lifespan of a UPS battery. On average, a battery will last anywhere from 3-5 years.

Why did my UPS suddenly stop working? ›

There are two possible reasons for this. Your computer load is higher than ups capacity. Change over time of UPS from mains to battery is high. Battery is bad and is not able to take sudden load.

How long will a UPS last without power? ›

For most typical computer workstations, one might have a UPS that was rated to keep the machine alive through a 15 minute power loss. If it is important for a machine to survive hours without power, one should probably look at a more robust power backup solution that includes a generator and other components.

Can UPS work without battery? ›

Offline UPS does not provide any feature without battery. Line interactive UPS provides only very limited features (voltage regulation) to load without battery. That's the idea both offline and line interactive UPS always should work with battery only.

Do and don'ts for UPS? ›

Do's & Don'ts
  • Ensure UPS is kept in 'ON' position 24×7 basis.
  • UPS should be placed in Dust Free and clean environment.
  • Install proper cooling systems in UPS room or ensure proper cross ventilation for better performance of UPS and batteries.
  • Ensure no raptiles like mouse, lizard in UPS room.

Is it OK to keep UPS plugged in all the time? ›

Should I Keep My UPS Plugged in at All Times? Yes, your UPS devices should always remain connected to grid power. If you experience bad power quality or a power outage, it can happen so suddenly that you may not have time to plug the ups in and switch it on.

What are 5 things that shorten the life of a battery? ›

Factors that can shorten its life include an extended period of partial or full discharge, vibration from not being properly secured, under- or overcharging, extreme temperatures, water loss, electrolyte contamination and corrosion on terminals.

What affects UPS battery life? ›

There are five primary factors that affect UPS battery life: ambient temperature, cycling, battery chemistry, application and maintenance. The rated capacity of a battery is based on an ambient operating temperature of 25°C (77°F).

How often should you service a UPS? ›

It is recommended that a UPS should be serviced annually. For your generators, regular weekly start-ups as well as an annual service is usually recommended. You should change air and oil filters, clean the unit and carry out all of the other checks recommended by the generator manufacturer.


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