APC UPS Battery Not Detected. How To Troubleshoot?

The heart of an APC UPS unit is the backup battery that’s stored inside. As such, most of its functionality is gone when the unit doesn’t have a battery or can’t detect one. But why would an APC UPS fail to detect its battery?

If an APC UPS can’t detect the battery inside, start by performing a hard reset. That could clear up any short-term errors or glitches preventing it from detecting the battery. Besides that, the battery’s connectors could be loose or disconnected, or the battery could have no charge. A worn-out or faulty battery can also be impossible for the unit to detect.

The following sections of this guide will help you understand why your APC UPS fails to detect its battery and how you can fix the problem.

Why Is My APC UPS Not Detecting Its Battery?

Here’s why your APC UPS fails to detect its battery and how you can resolve the issue:

UPS Requires A Hard Reset

What it is: You can perform a hard reset on a UPS to clear any short-term errors or glitches affecting its functionality. 

The procedure is also referred to as a ‘brain dead’ when it comes to the APC brand of UPS devices. However, it’s an effective way of resetting the unit’s microprocessor and allowing it to start over without any errors.

What happened: A standard UPS contains one or more batteries and several electronic components that control their functionality. One such component is the microprocessor which monitors the unit’s condition and ensures it works correctly.

Among other things, the UPS unit’s electronic components are responsible for detecting the battery inside the unit and monitoring its condition.

Unfortunately, electronic components can develop glitches or short-term errors, like failing to detect the onboard battery. Such glitches are challenging to identify, but their causes can also be too difficult to pinpoint.

Thankfully, such devices can work normally again by restarting or rebooting. In an APC UPS, you can achieve that by performing a hard reset, also known as a ‘brain dead’.

How to fix it: Follow these steps to perform a hard reset on your APC UPS:

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  1. Firstly, disconnect any devices you’ve plugged into the UPS.
  2. Secondly, unplug the UPS from the wall socket.
  3. Open the UPS casing so you can access the batteries and undo their connectors.
  4. While those batteries are unplugged, press and hold the ON button on the UPS control panel for 5 seconds.
  5. Finally, reconnect the battery and replace the panels you removed earlier. You can also plug the UPS into a working wall socket and turn the unit on.

Following those steps will complete a hard reset on your UPS. The unit will then restart and detect the onboard batteries.

Read: How To Troubleshoot UPS Battery?

Battery Connectors Are Loose Or Disconnected

What it is: The UPS unit’s casing is meant to house one or more backup batteries. Those batteries have connectors that you must keep attached to those inside the UPS.

When those connectors are firmly attached, they allow the batteries to charge and discharge power while communicating with the UPS’ electronic components.

What happened: Another reason your UPS can’t detect its battery is that the connectors within are loose or have somehow come undone.

APC UPS units aren’t moved around a lot, nor do they have moving parts. So, loose or disconnected battery connectors aren’t a regular occurrence.

However, the odds of that happening increase if you’ve opened the UPS to perform replacements or repairs on the unit. When that happens, the battery connectors were likely replaced incorrectly or accidentally detached.

How to fix it: Thankfully, the solution to this problem is very straightforward. First, you’ll have to access the inside of the APC UPS unit to inspect the battery connectors. If they are loose or have come undone, reconnect them firmly.

Doing that will allow the UPS to detect the battery inside and monitor its status.

Read: How To Check UPS Battery Health?

Battery Is Worn-Out Or Faulty

What it is: A typical backup battery that you’d find in an APC UPS will last between 3-5 years. As the battery approaches the end of that lifespan, it’ll display many signs of wear, like a gradual drop in performance and excessive temperatures.

What happened: One of the possible symptoms of a worn-out backup battery is that it can no longer communicate with the UPS. The same will also happen if you, unfortunately, were supplied with a faulty battery when you purchased the UPS unit.

Whether the battery is faulty or worn out from old age, the electronic components of the UPS (like its microprocessor) will likely fail to detect the battery.

How to fix it: There is nothing you can do to restore a backup battery at the end of its lifespan or fix one that’s faulty. The only solution here is to replace the affected battery with a new one in excellent working condition.

Read: What Happens When UPS Battery Fails?

Battery Has No Charge At All

What it is: The amount of power used from a battery’s total capacity is known as its depth of discharge. Typically, a UPS backup battery will not discharge its stored energy to 0% or until there’s absolutely nothing left. 

Allowing itself to reach that depth of discharge will reduce the battery’s lifespan significantly.

Instead, the maximum depth-of-discharge for a UPS battery is usually only up to 70%. As a result, the battery will continue to maintain the remaining power to maximize its lifespan. That remaining power also allows the UPS to detect the battery and monitor its condition. 

What happened: Electronic components in the UPS, like its microprocessor, control the battery and help it maintain a safe depth of discharge.

Unfortunately, there are other ways that a backup battery can discharge its power. For example, a UPS battery in storage will continue to release its stored energy over an extended period.

If left for too long, the battery will be completely flat and have no power. When that happens, the UPS can’t detect the battery or monitor its condition.

How to fix it: This problem is sometimes fixable but always preventable. Firstly, you can prevent this by always keeping your UPS plugged into a wall socket. That way, the unit will continuously maintain a full charge in the battery.

You can try recharging a flat battery again. However, it will only function correctly afterwards if it hasn’t experienced excessive wear.

Remember: when a battery goes beyond its proper depth of discharge, it experiences a lot of excess wear that shortens its lifespan.

Read: How To Tell If UPS Battery Needs Replacing?

Frequently Asked Questions (FAQs)

Below are a few more questions and answers that you’ll find helpful when troubleshooting your APC UPS backup battery:

Can APC UPS Work Without A Battery?

Some UPS models can function perfectly fine on AC power despite having no battery. However, other models will not work if the battery has been removed or is faulty.

Which Battery Is Used In APC UPS?

APC UPS models typically use Valve Regulated Lead Acid (VRLA) batteries. These batteries function by recombining hydrogen and oxygen to store power and do not emit excess gasses when functioning normally.

Can APC Battery Be Replaced?

Yes, an APC UPS battery can be replaced. Usually, you’ll have to replace the battery every 3-5 years or once the battery stops performing at an acceptable level.

How Often Should You Replace Batteries In A UPS?

UPS batteries typically last between 3 to 5 years. So, you should replace them once within that time frame. However, batteries that wear out prematurely need to be replaced immediately to ensure the UPS can function correctly.

Read: What Are UPS Battery Failure Symptoms?

How Do I Know If My UPS Battery Needs To Be Replaced?

You’ll know your UPS battery needs to be replaced when the battery replacement indicator lights up on the front panel (if there is one). Besides that, you should also replace the battery when it reaches the end of its lifespan or when its performance has dropped significantly.

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