What Happens When UPS Battery Fails?

A UPS battery backup is a fail-safe that protects your devices during a blackout. When there’s an electrical disruption, the UPS battery will keep your devices running by supplying it with backup power. Unfortunately, UPS units can fail, and you need to know what happens when they do.

When your UPS battery fails, it won’t supply power to your devices when you need it the most, i.e. during a power outage. At the same time, the UPS unit will flash visual indicators like warning lights and audible alerts like beeping alarms to let you know that the battery is failing. Physical symptoms are also common, with batteries swelling or overheating when they fail.

As you read this guide, you’ll better understand what happens when your UPS battery fails. That way, you can recognize when a failure occurs and respond accordingly.

Common Signs of a Failing UPS Battery

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End of Natural Lifespan: The battery is approaching or has surpassed its standard 3-to-5-year operational lifecycle.

Repetitive, False Alarms: The unit repeatedly emits warning beeps or overheating tones even when operating under normal conditions.
Flashing Control Panel Lights: LED indicator lights flash continuously or erratically without a clear external power issue.

flashing lights on UPS indicate failure of the battery

Abnormally Slow Charging: The battery requires significantly more time than usual to reach full capacity due to degraded internal chemicals.
Rapid Power Discharging: The unit loses its charge quickly and cannot sustain connected devices for its rated runtime during a outage.
Physical Battery Swelling: The outer casing of the battery expands or bloats, signaling a dangerous buildup of internal gases or heat.
Low Voltage Test Results: Manual testing with a multimeter reveals that the battery can no longer maintain its required baseline voltage output.

Burning or Foul Odors: The unit emits strange chemical smells or a distinct burning odor, indicating severe overheating or a dangerous thermal runaway scenario.

What Happens When My UPS Battery Fails?

Keeping your UPS battery in excellent working condition is critical to prevent it from failing. After all, the whole point of investing in a UPS is to ensure that there’s a backup power supply to keep your devices running during a power outage.

Still, it’s also crucial that you know what to expect during a UPS battery failure.

Here are 5 things that will happen when your UPS battery is failing:

#1 Devices Are Still Receiving Power

Firstly, you have to understand that a UPS battery failure can be a silent problem that goes unnoticed for a long time.

That’s because the power outlets on a UPS will continue to work and provide power to the devices plugged into it, even if the internal battery is no longer functioning.

More specifically, those power outlets will continue to work normally as long as electricity is supplied to the UPS from the wall socket.

In other words, you could be using a UPS with a failed battery and not even realize it until later.

That’s why you must inspect your UPS battery from time to time. Doing that will help you find signs of battery failure early, so you don’t experience more severe battery failure outcomes like the other items listed below.

#2 Device Damage During An Outage

The whole purpose of investing in a UPS is so that there’s backup battery power to keep devices operational during a power outage. In doing so, devices like computers and servers can be shut down using the correct process, thereby preventing any damage.

That’s why one of the worst things that can happen when a UPS battery fails is that it cannot perform its primary task of protecting your devices from a sudden shutdown.

For many electronic devices, a sudden shutdown is very damaging. That’s because they’ll shut off instantly when there’s no power coming through the wall socket.

Sadly, you’ll only discover this sign of battery failure when it’s too late, i.e. when a power supply disruption happens.

That’s another reason you should check your UPS batteries occasionally to ensure that the battery is still working. More specifically, you must ensure the battery is still within its service life and has no problem charging and discharging electrical power.

#3 UPS Overheats

UPS battery failures don’t necessarily happen all at once. Instead, batteries will deteriorate gradually over an extended period, resulting in a slow but certain performance loss.

For example, a UPS battery that’s aging and has experienced excess wear will see changes in its internal chemistry. As a result, the electrical resistance inside will continue to grow, and that will cause the battery to overheat more and more.

When that deterioration continues for long enough to the point of failure, the batt ery will produce so much excess heat that it’ll cause the entire UPS unit to overheat.

At that point, the built-in ventilation fans won’t be enough to keep the UPS and its battery cool, and it’ll be dangerous to continue using the unit.

#4 Flashing Lights Or Indicators

Most UPS batteries will have flashing lights or other visual indicators to tell you they are failing. These lights or indicators can vary in how complex they are depending on the UPS brand and model that you have.

For instance, entry-level UPS units typically only have a few colored LEDs on their front panels that turn on when the battery fails.

However, more sophisticated models tend to feature small LCD-type displays that will provide you with much more information. For example, those LCDs can tell you much more about the battery failure with error codes that explain the root causes.

#5 Audible Alarms Triggered

Aside from visual indicators, most UPS models also come with audible alarms. Typically, those alarms will play beeping sounds that are loud enough to catch your attention and warn you of a battery failure.

The beeping alarms on a UPS can also communicate several different things. For example, the occasional beep typically means the UPS works normally without any battery failures.

However, a continuous beeping sound is usually how a UPS warns you of an ongoing battery failure that requires your immediate attention.

What Do You Do When A UPS Battery Fails?

When a UPS battery fails, you must replace it as soon as possible to enjoy the protection a UPS provides. In the meantime, however, the UPS can work without a battery.

Your devices will continue receiving power from the UPS as long as it’s plugged into a working wall socket.

But before you remove the failed battery, you must also resolve the root cause of its failure. That way, it won’t cause the new battery to fail the same way.

For example, a typical cause for a UPS battery failure is overheating. That can happen due to a lack of cooling or because the built-in ventilation fans have stopped working.

In that case, you must ensure that the UPS has sufficient cooling and ventilation so that the new battery doesn’t fail for the same reasons.

Why Does My UPS Battery Fail Prematurely?

A typical UPS battery has a lifespan of 3-5 years. So, it’s certainly not normal for a battery to last only 10-12 months.

If you find that your UPS battery fails prematurely, here are the likely causes that you should consider:

High Surrounding Temperatures

What it is: All UPS batteries have an optimal operating temperature range. If the unit stays within that range, it will continue to function optimally and avoid unnecessary wear.

You see, backup batteries don’t do well in extremely high or low temperatures. That’s particularly true in higher temperatures, as excess heat can cause plenty of problems for a UPS battery in the long run.

What happens: When the lifespan of your UPS battery can’t seem to go beyond 10-12 months, it’s likely because of excess wear due to high surrounding temperatures.

Those high temperatures will make it impossible for the UPS unit and its internal batteries to keep themselves cool.

When that happens continuously, it will cause the UPS to wear out prematurely, including the battery.

How to fix/prevent it: The solution to this problem is to ensure that your UPS is placed in a room with a constant and reasonable temperature. Depending on your unit, you might have to cool the surrounding area much more.

Heavy-duty industrial UPS models must be placed in an air-conditioned room.

So, check your UPS user manual to see what the surrounding temperatures for that model must be.

Internal Overheating

What it is: The UPS’ surrounding temperature isn’t the only thing that must be controlled. The UPS’s internal temperature is another crucial factor that can affect the battery’s lifespan.

All UPS models will have ways of controlling their own temperature. For example, plenty of them have built-in cooling fans that ventilate hot air out of the UPS unit so it can stay cool inside.

What happens: Unfortunately, the UPS can also overheat from the inside. That will occur when the built-in fans fail or become clogged with dust.

So, even if the surrounding areas are at a cool temperature, the UPS will fail to ventilate the heat it generates from within.

That will cause the unit to overheat and wear out its batteries, dramatically reducing its lifespan to 12 months or less.

How to fix/prevent it: You can avoid internal overheating by cleaning the UPS fans regularly. Brushing away dust on the fans will go a long way to ensure they can continue operating efficiently to remove hot air from within the UPS.

Discharged Too Often

What it is: The lifespan of a UPS backup battery also depends on how many times it charges and discharges. Typically, a UPS continuously recharges until there’s a power outage.

When that happens, the battery begins to discharge the power it stores inside.

Aside from power outages, the battery will also discharge whenever you disconnect it from the wall socket. With no incoming power, the UPS will automatically begin discharging its batteries.

What happens: Every time a UPS battery goes through a discharge/recharge cycle, it loses just a little bit of its lifespan. The more that happens, the quicker the battery will wear out entirely, which might explain why yours only lasts 10-12 months.

Repetitive discharging might happen if your area is prone to power outages or disruptions. Besides that, some users disconnect their UPS units often and use them as a mobile battery pack.

Those factors will result in more charge-discharge cycles, which wear out the battery and shorten its lifespan.

How to fix/prevent it: If your UPS battery is already failing, you must replace it with a new one. Unfortunately, there’s no way to restore the battery’s lifespan and make it last longer.

Once you get a new battery, you should reserve the UPS for emergency use only. That way, you’ll ensure that the battery will only be discharged if there’s a power outage.

With fewer charge-discharge cycles, you’ll maximize the battery’s lifespan to where it should be, typically 3-5 years.

Continuously Overcharging

What it is: In the past, a battery would overcharge if you left it connected to a power source for too long. That doesn’t happen these days, especially in modern UPS battery backups.

The reason for that is pretty straightforward: all UPS models have electronic components that control how the device charges and discharges its power.

Once those components sense that the battery is fully charged, they will prevent the batteries from receiving more power. In doing so, they avoid overcharging and the problems that come with it.

That’s excellent news, considering how overcharging a battery affects the chemical reactions within and significantly reduces its lifespan.

What happens: Although less likely, the electronics controlling the UPS battery’s behaviors may have failed. They might have become faulty, worn out, or experienced some kind of electrical damage like a short circuit.

When that happens, the UPS unit will lose its ability to prevent overcharging. As a result, the UPS that you keep plugged into the wall socket will continue charging excessively.

If the UPS is left that way, the battery will quickly reduce its lifespan and begin failing despite only being used for 10-12 months.

How to fix/prevent it: As mentioned before, your UPS has electronic components that prevent it from overcharging. So, the only way to prevent yours from overcharging is to ensure that those components are always working correctly.

You can do that by checking on them periodically. Look for any warnings or error codes on your UPS that might suggest a problem with its components.

Should you find any problems, you must get them fixed by a qualified technician immediately. Delaying those repairs could cause more damage to your batteries and shorten their lifespan.

Frequently Asked Questions (FAQs)

A UPS battery failure can be pretty damaging and expensive to you. So, here are a few more questions and answers to help you understand your UPS backup battery.

What Is A UPS Failure?

A UPS failure is when the unit can’t provide backup battery power to your devices during a power outage. In other words, the UPS unit fails when it can’t perform its primary function of protecting the devices you plug into its power outlets.

Why Is UPS Not Working?

A UPS can stop working for several reasons. Firstly, the UPS won’t work if its internal batteries are old or not functioning correctly. As a result, those batteries can’t charge or supply power to anything you’ve plugged into the UPS. Besides that, overheating or a tripped circuit breaker can also cause the UPS not to work.

Are UPS Safe?

Yes, UPS backup batteries are very safe to use. However, you must ensure that the batteries in your UPS unit are in excellent working order. Old and neglected UPS batteries can swell and overheat, which can be dangerous for the UPS and anyone using it.

Why Is My UPS Battery Not Charging?

Firstly, check that your UPS battery backup receives power from the wall socket. Then, consider that your UPS battery will not charge if its connector is loose or has come undone. Lastly, old and worn-out batteries will also experience difficulties charging.