Why Does The UPS Make A Loud Buzzing Sound When Running On Battery?

A UPS backup battery is a straightforward device consisting of batteries and electronic components that control them. Still, these devices can generate several different noises as you use them. For instance, you might hear a loud buzz when the unit runs on battery power.

A UPS running on battery power might produce a loud buzzing sound for non-problematic reasons like a functioning inverter or a cooling fan running at high speeds. Some UPS units might also sound the same when performing a self-test. However, the sound could also point to problems like an old or faulty battery that isn’t working so well anymore.

Keep reading to understand more about why your UPS is buzzing loudly and what you can do to stop the noise.

Why Is My UPS Buzzing When Running On Battery?

A buzzing noise coming from your UPS isn’t necessarily the sign of a problem. So, there’s no reason to panic.

However, it would be an excellent idea to troubleshoot your UPS as soon as possible to rule out or fix any issues that might be present.

Here’s why your UPS is buzzing when running on battery and what you can do to fix it:

Normal Inverter Buzzing

What it is: Your UPS has an inverter built into the unit. The reason is that the battery power stores direct current (DC) electricity, but the devices you plug into the UPS require alternating current (AC) electricity.

So, the inverter’s purpose is to invert that DC power back to AC to keep your devices running during a power outage or disruption.

Why it happens: The first likely reason your UPS is making a loud buzzing noise might not be a sign of a problem. Instead, the sound could be coming from the inverter running and doing what it’s supposed to do.

A typical inverter buzzing noise isn’t very loud. However, the location you choose for the UPS might cause the buzzing noise to become amplified. 

That’s especially true if boxes or other items are placed around the UPS, allowing the buzzing sound waves to bounce around and seem louder than they really are.

How to fix it: If your UPS inverter is buzzing as it should, there’s nothing you’ll have to do. First, however, you should refer to the user manual to ensure that the sound you hear is typical.

Typically, UPS manufacturers will include information in their manuals about what noises coming from the unit are normal or not.

Read: How To Troubleshoot UPS Battery?

Fan Running At High Speeds

What it is: UPS backup batteries typically come with built-in cooling fans. These fans run continuously to ensure the UPS is kept within safe operating temperatures.

In doing so, the cooling fan helps the backup battery function optimally by preventing it from overheating.

Why it happens: The second non-problematic reason you’re hearing a loud buzz coming from your UPS backup battery is that the cooling fan is running at high speeds.

As mentioned above, the purpose of the fan is to keep your UPS within safe operating temperatures. So, the fans will only spin at low speeds when the unit is cool.

However, the UPS will get significantly warmer when discharging its battery power. As that happens, the UPS will start running its fan at higher speeds, producing a loud buzzing noise.

How to fix it: A UPS cooling fan that runs at high speeds isn’t a problem. However, you should take a moment to find out why your UPS is getting warmer.

If the UPS is getting warm because it’s running on battery power, there’s nothing to worry about.

However, you should be concerned if the UPS is heating up due to a lack of ventilation or air conditioning. In that case, maximizing ventilation and air conditioning will help the UPS stay cool and stop it from running its fans at high speeds.

Read: Why Ups (Battery Backup) Is Beeping Continuously?

UPS Unit Is Currently Self-Testing

What it is: Many UPS models today come with various self-testing features. In simple terms, those features will periodically test the UPS to ensure it’s still functioning correctly.

If the self-testing feature finds a problem, it will alert you by flashing its indicators, beeping continuously, and displaying an error code.

Why it happens: UPS backup batteries will run their self-testing feature automatically. When that happens, some UPS models will give off a loud buzzing noise you can hear if you’re close by.

How to fix it: When you find that your UPS backup battery is buzzing during a self-test, the only thing you have to do is let it continue and finish with the test.

However, you should always refer to your user manual to see if this is normal behavior for your particular UPS model. The user manual should have details of how and when the unit will perform its self-tests.

Read: How To Check UPS Battery Health?

Old Or Faulty Battery

What it is: Every UPS unit includes one or more batteries inside that hold backup power. Unfortunately, all backup batteries have a limited lifespan. 

A typical UPS backup battery will last for 3-5 years. However, the battery will become unreliable towards the end of its lifespan, so you’ll want to replace it as soon as possible.

Why it happens: Two things will happen as the battery reaches the end of its lifespan and becomes faulty. Firstly, the battery will start to experience a drop in performance. That means the battery slowly loses its ability to charge and discharge power normally.

Secondly, the battery will demonstrate signs of extensive wear. For example, the battery will give off a loud buzzing sound whenever it’s discharging power. 

How to fix it: An old or faulty UPS battery cannot be fixed. So, your solution to this issue is to buy a new replacement battery.

Always remember to invest in the highest-quality battery that fits your budget. Purchasing a battery compatible with your UPS model and from a reputable manufacturer will help you ensure its reliability.

Read: What Happens When UPS Battery Fails?

Frequently Asked Questions (FAQs)

Need some extra help understanding your UPS backup battery? Check out these helpful questions and answers:

Why Is My UPS Making Noises?

If your UPS is in excellent working condition, it’s normal for the unit to make a few noises during its regular operation. For example, you might hear the occasional beep or a gentle humming sound from the unit. Always refer to the user manual to understand which noises are normal and which ones are a sign of a problem.

Read: Can A UPS Last For 3 Hours?

Is UPS Supposed To Make Noise?

Yes, a UPS is supposed to make noises. As mentioned above, some noises are part of the unit’s regular operations. However, some noises are clear signs of a problem. For example, your UPS might beep continuously or produce a loud buzzing sound when there’s a problem.

How Do I Stop My UPS From Making Noise?

Solving a noise coming from your UPS will depend on the noise and why it’s happening. For example, you can mute or silence the regular beeping noises from a UPS. However, loud buzzing noises from the fan might require you to clean dust from the unit and maximize ventilation around it.

Can UPS Explode?

Yes, a UPS can explode in a worst-case scenario. That’s why you must investigate your unit’s loud and unusual noises. You’ll also find it helpful to learn which noises are part of the unit’s normal operations and which ones are problematic.

Is It Ok To Keep UPS Plugged In All The Time?

Yes, it’s an excellent idea to keep your UPS plugged in. That way, the UPS will keep itself fully charged and ready to use during a power outage or other emergencies.