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Batteries, UPS

10 Things You Need To Know About UPS Batteries

While undeniably the heart of any uninterruptible power system (UPS), batteries unfortunately are also the most vulnerable aspect. In fact, battery failure consistently ranks among the most common causes of load loss. Understanding how to properly maintain and manage UPS batteries is not only instrumental to extending their service life but can also help thwart costly downtime. Bolster your battery knowledge with these 10 truths:

1. All batteries will experience an “end of useful life”The IEEE defines a UPS battery’s “end of useful life” as the point when it can no longer supply 80 percent of its rated capacity in ampere-hours. At this stage, the aging process accelerates and you should replace the battery. Although the average lifespan for VRLA batteries is three to five years, actual life can vary dramatically due to environmental conditions, the number of discharge cycles and the amount of maintenance received.

2. Batteries die for a variety of reasons – Among the most common causes of battery failure are high or uneven temperatures; inaccurate float charge voltage; loose inter-cell links or connections; loss of electrolyte due to damage or drying out; lack of maintenance; and aging.

3. VRLA and VLA are the two most common types of UPS batteries – Valve-regulated lead acid (VRLA) batteries, also known as sealed or maintenance-free, are batteries that have been encased to prevent any liquid from leaking. Vented Lead Acid (VLA), also known as flooded or wet cell, are comprised of a hard enclosure, lead plates and an electrolyte that allows the flow of current. Don’t miss our next blog, which will explore both of these battery types in much greater detail.

4. Different UPS systems use different batteries – While basic battery technology — and the risks to battery life — remain the same regardless of UPS size, there are some differences between applications. Smaller UPS’s (250VA to 3kVA range) typically contain a single VRLA battery, while the use of wet-cell batteries becomes much more common in bigger systems.

5. Your UPS maintenance plan should cover the batteries, too – A solid, comprehensive service plan will include both the UPS components and the batteries. Regularly scheduled preventive maintenance visits allow trained technicians to inspect, test, calibrate and upgrade battery components, ensuring factory-specified performance and longevity.

6. The battery type will dictate maintenance requirements – The type of batteries will impact which maintenance tasks need to be performed and their frequency, with wet cell batteries requiring more maintenance than VRLA. However, even batteries that claim to be “maintenance-free” still need regular inspection, cleaning and testing.

7. Stored batteries require attention, too – If UPS batteries sit unused with no charging routine, their life will decrease. Due to the self-discharge characteristics of lead-acid batteries, it is recommended that they be charged every three to four months when in storage to avoid permanent loss of capacity (which will occur between 18 and 30 months). To prolong shelf life without charging, store batteries at 10°C (50°F) or less.

8. There is a difference between hot-swappable and user-replaceable batteries – Batteries can be both hot-swappable and user-replaceable. Hot-swappable batteries are able to be changed out while the UPS is running. User-replaceable batteries, which are generally found in smaller UPS’s, indicates that no special tools or training is needed to replace them.

9. A battery’s discharge rating is key to measuring performance – Batteries are generally rated for more than 100 discharges and recharges. However, many will display a marked decline in charging capacity after as few as 10 discharges. The lower the charge that the battery can accept, the less runtime it is able to deliver. Be sure to look for batteries with a high-rate design that sustains stable performance for a long service term.

10. Thermal runaway can have explosive consequences – Often occurring without any warning signs, thermal runaway takes place when the heat generated in a lead-acid cell exceeds its ability to dissipate it. Typically caused by overcharging, excessive charging, internal physical damage, internal short circuit or a hot environment, thermal runaway can result in an explosion, especially in sealed cells.

Batteries, UPS

Knowledge is Power: Understanding UPS battery options

When it comes to the batteries within uninterruptible power systems (UPSs), one size doesn’t fit all.

In fact, for decades, most smaller standby systems have used sealed VRLA batteries, while larger double-conversion systems have typically relied on flooded-cell VLA batteries.

There’s also a relative newcomer to the family, as lithium-ion has joined the two decades-old siblings. Here, we break down the UPS battery family tree:

1. Valve Regulated Lead Acid (VRLA). Commonly referred to as sealed lead-acid (SLA) or maintenance-free, VRLA batteries are the most common type of UPS battery.

Lower upfront costs, relative safety, easy availability and minimal maintenance are the primary advantages of this battery. However, deeming VRLA batteries “maintenance-free” is slightly inaccurate, as they still require regular cleaning and testing.

On the downside, sealed batteries have a short lifespan of about 3 to 7 years. The term ‘valve regulated’ represents the manner in which gas is released from a VRLA battery; if pressure becomes too great, a valve will vent the gas.

Because heat is detrimental to this type of battery, their optimal environment is a dry, temperature-controlled area of 77 degrees or lower.

It is important to note that since water cannot be added to most VRLA batteries, anything that increases the rate of evaporation or water loss — such as temperature or heat from the charging current — will subsequently reduce the life of the battery.

a. Absorbent glass mat (AGM). AGM batteries are a subtype of VRLA batteries. In AGM batteries the electrolyte is held in woven glass fiber mats.
This design allows for flexibility of design, improved self-discharge rates, and a wider operational temperature range.
b. Gel Cell. The second VRLA subtype. Originally conceived during the early 1930s for use in portable electronics early gel cells were less likely to leak when handled roughly.
A modern gel cell uses an electrolyte mixture usually comprised of sulfuric acid mixed with pyrogenic silica resulting in a gel like substance.
Gel cells are known for increased tolerance to vibration, as well as allowing for the lower cost 1-12 Amp hour range VRLA batteries found in smaller UPS systems.

2. Vented Lead Acid (VLA). Also known as flooded or wet cell batteries, VLA not only boast exceptional reliability, but an average lifespan of 20 years.

Composed of thick, lead-based plates flooded with electrolyte acid, these batteries typically have higher upfront costs than their VRLA counterparts, as well as pose a number of safety concerns.

As a result, they require regular maintenance and careful handling because their liquid is corrosive and can be set off by forceful movement.

Wet cell batteries should only be used in areas with proper ventilation and must be adequately protected against vibration and shaking due to the possibility of liquid spilling. In addition, they are prone to damage in extreme climates as the water inside can evaporate or freeze.

Even though wet cell batteries require more maintenance and are more expensive to replace, they are a highly reliable power source for double-conversion UPSs.

3. Lithium-ion. The new kid on the block when it comes to UPS applications, lithium-ion batteries have matured significantly in recent years, both in their design and range of potential uses.

Lithium-ion creates a safe and stable alternative battery option for UPSs, with benefits that include longer lifespan, weight reduction, smaller footprint and expanded warranty coverage.

While originally deployed as battery cabinets in three-phase UPS installations, there are now smaller single-phase lithium-powered UPSs on the market.

Although this type of battery tends to be more expensive than the other two options — which is expected to change as adoption rates become more widespread — lithium-ion batteries offer lower long term operational expenses since they last longer.

While each of the three types of UPS battery has its own set of advantages and disadvantages, it is important to understand your options — not to mention, how to best manage and maintain them.

One battery pitfall to avoid at all costs is thermal runaway, a topic we explored in our last blog.

Batteries, UPS

Requesting UPS battery replacement: When, Why and How?

The best approach to ensuring the ongoing health of your uninterruptible power system (UPS) batteries is to heed the advice popularized by the Boy Scouts of America — be prepared

One merit badge that is essential to complete: Requesting a battery replacement proposal from a qualified UPS service provider.


Most people understand that batteries are the heart of any UPS.

Yet they also are the most common cause of UPS failure; research shows that up to 20 percent of all UPS failures can be attributed to bad batteries.

Under optimal operating conditions, most VRLA batteries have a maximum life expectancy of five years.

Yet these batteries can fail much faster in less ideal environments, such as those that don’t maintain an ambient temperature of 77°F, or where recurrent power problems cause batteries to cycle frequently.

Battery life can also be significantly reduced if an organization doesn’t engage in regular service and maintenance, which are essential to ensuring ongoing UPS reliability.

However, even UPS batteries that are well cared for will nonetheless require replacement at some point.

This is due to the fact that they are electrochemical energy storage devices that convert chemical energy into the electrical energy UPS’s use to operate, and over time the chemicals deplete.

Need help deciding on a UPS? Get a free site assessment!

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Being prepared means thinking ahead. Don’t wait until your UPS batteries hit their fifth birthday to start preparing for their replacement.

Instead, begin requesting replacement quotes as batteries are approaching their fourth year.

This way you have one or more proposals on hand when the time arrives. In addition, track UPS preventive maintenance calls and take the time to read service reports closely.

If there are any possible impending signs of failure, take steps to replace the batteries right away.


Regardless of your current UPS maintenance provider, consider requesting a battery replacement proposal from Unified Power and share it with your management for review and budgets.

Once the proposal is shared with management, the decision to move forward is now in their hands.  It is no longer your responsibility if the unit is compromised due to battery failure. 

And if you aren’t currently engaging in regular service with a preferred maintenance provider, now is the perfect time to consider protecting your equipment — and your overall organization — with a UPS maintenance contract.

You’ll not only receive an update on the overall health of your unit and its batteries, but when replacement time arrives, you’ll already have an established relationship with a provider you trust and who has worked on your equipment.

If you are working with Unified Power, please reach out to your account manager, as they can review your last PM/service report with you and discuss what to expect in the future.

Being prepared has never been so easy!

Still have questions? Get a response immediately.

Click above to get started or call 240.772.1710 for instant help.

Batteries, UPS

One is the Loneliest (and Most Dangerous) Number: Why You Need Multiple Battery Strings in Your UPS

When it comes to UPS batteries, there are two rudimentary — and yet somewhat contrasting — truths.

First, batteries are the heart of any UPS system. And second, they can be inherently unreliable.

Because of that, it is recommended that you deploy multiple strings of batteries to ensure your UPS performs as expected during a power outage.

Studies have shown that battery failure is one of the leading cause of load loss.

Likewise, it has been well documented that equipping a UPS with multiple battery strings in a parallel configuration can dramatically reduce that risk.

In recent years, there have been improvements in battery technology that have reduced the threat of unexpected failure, including advanced charging techniques, software management, and firmware upgrades that add intelligence.

Yet none of these capabilities can completely eliminate the risk of battery failure.

Need help deciding on a UPS? Get a free site assessment!

Click above to get started or call 240.772.1710 for instant help.

One of the simplest and most cost-effective ways to prevent the loss of a critical load during a power outage is to equip your UPS with at least two battery strings.

A string of UPS batteries is often compared to a string of holiday lights; if one fails, the entire chain goes dead.

Although one faulty UPS battery doesn’t necessitate having to replace the entire string, determining which battery has failed can be challenging.

Even more, it is crucial to test the cell level health of the entire string in order to identify if other units have been damaged by strain from the faulty battery.

The most effective plan of attack is to spot-replace bad batteries that are less than two years old and swap out the entire string between the fourth and fifth year.

Continuous battery monitoring, coupled with scheduled maintenance, is the only way to identify bad batteries early enough to complete a spot replacement.

To reduce the risk of unexpected load loss from a failing UPS battery, it is wise to invest in a UPS that offers the option of multiple battery strings.

By tying together battery strings in a parallel configuration, it eliminates a single point of failure in the UPS.

For example, consider a UPS system that has 20 batteries connected in a series. If a problem occurs in any of those batteries, the entire string will likely fail, taking the UPS — and your critical load — down with it.

Yet by adding another 20 batteries in a parallel configuration, if either string fails, the UPS has the capacity to continue operating for a limited time on the other string until either a backup generator comes online or the connected load is safely shut down.

Although the upfront investment in additional battery strings will run more than a single string, consider the alternative: for Fortune 1000 companies, the average total cost of unplanned application downtime per year is $1.25 billion to $2.5 billion; the average hourly cost of an infrastructure failure rings in at $100,000 per hour; and the average cost of a critical application failure per hour is $500,000 to $1 million.

Indeed, the dollar amount required to bolster availability through the purchase of additional UPS batteries is dramatically less than the price tag associated with potential downtime, which can include equipment damage, loss of application services, data loss, damage to reputation and loss of productivity, among other costly consequences.

Still have questions? Get a response immediately.

Click above to get started or call 240.772.1710 for instant help.

Batteries, UPS

Enersys 16V Front Terminal UPS Battery in short supply

Enersys 16V Front Terminal UPS Battery in short supply – read more about what this means for users…

  • DataSafe 16HX550F-FR
  • DataSafe 16HX800F-FR
  • DataSafe 16HX925F-FR

Enersys introduced the world’s first 16 volt front terminal UPS battery several years ago.

This battery has many advantages over typical 12V batteries, chief of which is a high power density in a very small footprint.

Your typical UPS runs on a 540V DC Buss which consists of (40) 12V batteries connected in series. With the Enersys 16V battery, you only need (30) batteries to make up one string.

Also – the Enersys battery is narrow in the front, but deep, further reducing space.

In order to take advantage of the smaller footprint, special, smaller battery cabinets were designed specifically for the 16V Batteries.

While all of this is good news for greater power density, it is not without a downside that can be disastrous if you’re not aware.

None of the other major battery manufacturers have jumped on the 16V battery bandwagon, so currently Enersys is the only manufacturer offering this battery.

This means that you will pay a premium for replacement batteries every 4-5 years.

You are also at the mercy of factory lead times, so if the current lead time is 17 weeks (which it was in April 2016 for the 925’s) there is nothing you can do about it.

If you opt for a different battery, you will need to replace your UPS battery cabinets in order to switch over.

If you are in an emergency situation and need to replace your 16V batteries, 24/7 Technology can work with you to engineer an alternative solution to the Enersys 16V battery.

We also work with customers to pro actively replace their UPS battery systems with standard sizes and models that are readily available and cost effective.

The key is to be proactive and not get caught in a dangerous situation where your batteries are failing, and the lead time for new ones is 4 months.

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