How to Tell if a UPS Battery Needs Replacing

Old batteries are often the weakest link of any Uninterruptible Power Supply (UPS). Delivering emergency power supply to your electrical load in the case of a power failure, UPS systems allow your devices to keep running long enough for the generator to kick in or until a proper shut down can occur. They also protect your devices from power surges, brownouts, black outs, and power transients.

Most UPS systems rely on batteries as their source of power. However, batteries are often prone to failure, requiring replacement themselves. But how can you tell if a UPS battery needs replacing for sure? Here, we will outline a few of the warning signs, as well as ways to confirm the need for a replacement, and your options for doing so. Ready to get started? 

UPS Battery Replacement Warning Signs 

The Low Battery Alarm Has Sounded 

Most UPS systems come with a low battery alarm. The machine will run a periodic self-test, only giving an alert signal when a battery replacement is required. Usually, this signal takes the form of an indicator light or alarm sound. If you have a monitoring system set up, you may also receive alerts via email or alternative digital communication. 

Preventive Maintenance Visits 

Your UPS Service Technician will PM the batteries during your annual and semiannual UPS Preventive Maintenance Visit. They can easily compare your battery Midtronics readings to the OEM allowable specifications to ensure the batteries are good operating order. They can also lend expert advice and opinions on your battery's health and well-being based on their Midtronics readings.     

Strange Behavior & Symptoms 

When near failure, batteries will often begin to demonstrate strange symptoms you can use to judge the remaining life of your battery. Typically, repeating alarms, flashing panel lights, and strange terminal displays are all symptoms of a failing UPS battery.  

Old Age 

Every battery manufacture puts a date code on their batteries, telling you when your battery was made. In most cases, you should expect your UPS batteries to last a maximum of three to four years. While that lifespan can differ depending on the usage requirements of your system and your load, if batteries are nearing this age, it is likely time to consider a replacement.  

When the Battery Begins Shorting its Rated Capacity 

When your battery system can no longer supply at least 80percent of its rated capacity in ampere hours, it is a likely indicator that your battery needs to be replaced. Typically, when the battery reaches this percentage, the aging process will accelerate rapidly, ending the useful life of the battery. This can literally happen overnight. 

Early Discharge 

If your UPS batteries are taking longer to charge, and are self-discharging earlier than usual, it is a definite sign that the battery’s life is nearly over.  

How to Confirm Your UPS Battery Needs to Be Replaced 

When your battery begins to display any of the above warning signals, you will want to confirm whether it needs to be replaced or not. There are a few methods you can implement on your own to do so.   

First, Inspect the Batteries 

In some cases, you may be able to tell whether a battery needs to be replaced simply by looking at it. If you see any of the signs below, it is almost definitely a sign your battery needs immediate replacement: 

·       Broken terminals 

·       Bulges in the casing 

·       Cracks in the plastic 

·       Excessive leaking 

·       Or any discoloration 

These changes to the battery’s physical appearance can be indicators of a short, overcharging, or simply a lack of proper battery maintenance. If you have inspected the battery and found none of the above, move on to the next step.  

Take a Voltage Reading 

If you have a voltage reader on hand, or already integrated, hook it up to your battery and compare the voltage reading to the voltage the battery is supposed to be capable of providing. If it is significantly reduced while being charged, it could indicate any of the following scenarios: 

·       Your battery experienced a short circuit 

·       Your battery has a dead cell 

·       Your battery has become sulfated 

Sulfated batteries are usually unable to reach a full charge and will self-discharge far more quickly than a healthy battery. Any of the above scenarios will require a battery replacement. 

Battery Replacement Options 

UPS systems are already equipped with VRLA batteries and are typically replaced with a similar models. If you are looking for added runtime or redundancy, now would be a good time to discuss options with your service provider.  In some cases, you can fit larger amp hour batteries into your current cabinet to lengthen your runtime.  However, if you have the space, you can also add a second cabinet for redundancy.    

In the end, you can have your service company simply replace your UPS batteries with new ones every few years.  This will entail new batteries, new interconnects if needed, hardware torqued to the OEM specifications and battery monitoring devices if necessary. Sometimes you may want the replacement to happen during non-peak hours which can include nights or weekends so make sure they are able to accommodate your schedule.

Visit our construction division’s website for more information and an in-depth comparison of UPS Runtime Solutions.  

Facility Gateway Critical Services: Your UPS Service Partner 

FGC Service offers a wide variety of replacement UPS batteries and assistance for all Uninterruptible Power Systems. We understand the importance of proper UPS battery maintenance and the technical requirements needed to install and recycle any string of batteries.  

If you’d like to learn more about our battery replacement and monitoring services, check out our battery replacement guide.  

If you’d prefer to speak with one of our product specialists directly, we invite you to contact us via our online contact form, or start a chat with our team in the chat feature at the bottom right corner of this page! 

Posted on

March 4, 2021


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