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.

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.

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.

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.