Posted by The Battery Store Team on 2nd Jul 2025

The Ultimate Guide to UPS Batteries (2025)

Everything You Need to Know About Uninterruptible Power Supply Batteries

When the lights go out unexpectedly, your Uninterruptible Power Supply (UPS) quietly steps in to keep things running. Whether it’s protecting your PC from data loss, keeping your Wi-Fi alive during a power cut, or safeguarding servers in a commercial environment, the real hero is the UPS battery powering the backup.

But not all UPS batteries are made equal. In this guide, we’ll walk you through the different types of UPS batteries available in 2025, how long they last, when to replace them, and how to choose the right one for your system.

What Is a UPS Battery?

A UPS battery is a rechargeable battery that provides backup power when the mains electricity fails. It gives you enough time to safely shut down devices or continue running essential equipment like alarms, modems, CCTV, or even home medical devices.

If your UPS is the fire extinguisher of your electrical system, then the battery is the pressure inside it. Without a healthy, fully charged battery, your UPS is just a heavy plastic box.

Types of UPS Batteries You’ll Find in 2025

At BatteryStore.co.uk, we focus on three types of UPS batteries that cover 99% of home and business needs:

1. VRLA (Valve-Regulated Lead-Acid) Batteries

These are the most common and cost-effective type. They’re sealed, maintenance-free, and widely used in basic UPS systems.

  • Pros: Affordable, readily available

  • Cons: Lifespan is typically 3–5 years

2. AGM (Absorbent Glass Mat) Batteries

AGM batteries are a type of VRLA but offer better performance. They’re sealed, spill-proof, and can handle deeper discharges, making them ideal for longer runtimes.

  • Pros: Compact, reliable, maintenance-free

  • Cons: Slightly higher cost than standard VRLA

3. Lithium-ion (LiFePO₄) Batteries

If you’re after the best in terms of performance, safety, and lifespan, lithium is the way to go. These modern batteries come with a built-in Battery Management System (BMS) and offer up to 10 years of life.

  • Pros: Lightweight, long-lasting, fast charging

  • Cons: Higher upfront cost

When Should You Replace a UPS Battery?

Here are a few tell-tale signs that your UPS battery might be nearing the end:

  • Shorter backup time than usual

  • Warning lights or alarms on the UPS

  • Battery is more than 3 years old

  • Swelling, leakage, or discolouration

  • UPS software alerts (e.g., APC PowerChute)

If in doubt, most modern UPS systems have a built-in battery self-test feature—use it!

How to Replace a UPS Battery (Safely)

Changing your UPS battery isn’t as scary as it sounds. Most consumer-level UPS devices are designed to make it fairly simple.

Here’s how to do it:

  1. Turn off your UPS and unplug it from the wall

  2. Open the battery compartment (usually with a screwdriver)

  3. Disconnect and remove the old battery

  4. Insert the new battery, reconnect the terminals

  5. Close the panel and plug the UPS back in

  6. Let it fully charge, then run a self-test

Don’t forget to recycle the old battery properly. Most local councils or electronics retailers accept them under WEEE recycling schemes.

How to Choose the Right UPS Battery

Not all 12V batteries are created equal, and using the wrong one can damage your UPS—or just not work at all. Here’s what you should check before buying:

  • Voltage and capacity (Ah rating) – Must match your UPS specs

  • Terminal type – Spade or bolt-on?

  • Size and fit – Make sure it fits inside your UPS

FAQs

How often should I replace my UPS battery?
Every 3–5 years for AGM/VRLA, and up to 10 years for lithium batteries.

Can I use any 12V battery in my UPS?
No. It must be designed for UPS or standby use. Car or solar batteries are not suitable.

Do I need a special charger for lithium UPS batteries?
Not usually. If it’s a drop-in replacement, it will work with your existing UPS charging system.

Final Thoughts

Your UPS battery is like a seatbelt—it only matters when something goes wrong. Make sure you’ve got one you can rely on.

If you're not sure what battery you need, give us a ring. We're UK-based, and happy to help.