Do Fire Curtain Batteries Need to be Replaced after 2-years?

Updated: Apr 21

There is growing discussion in the industry surrounding the replacement of Fire Curtain batteries, and sometimes you just need a yes or no response. Especially when it is something as serious as Fire Protection measures.

So yes, Fire Curtain batteries should be replaced every 2 years.

But why do they need replacing so often, and what is the process of replacement?

Adexon® Fire Curtain batteries are lead-acid batteries and contain tightly packed lead (black lines) and lead oxide sheets (yellow lines) in a cell, surrounded by sulfuric acid, alternating throughout the battery[1]

Simplistic diagram of the inside of an Adexon lead-acid battery.

Simplistic diagram of the inside of an Adexon lead-acid battery.

A lead-acid battery works by converting chemical energy into electrical energy.

The battery generates electrical energy by completing a chemical reaction between lead, lead oxide, and sulfuric acid. This chemical reaction can cause a build-up of lead sulfate between the plates.

Over time, as the battery discharges, this chemical process results in lead sulfate building up between the plates. Too much of this build-up results in an inability to charge. Therefore, the Fire Curtain batteries need to be replaced around every 2 years, as continued use after this time could result in a battery back-up that does not charge, and then does not deploy the curtain if mains power fails, leaving building users at risk from fire and smoke spread.

This is also in keeping with the use-by date given on the packaging, and battery itself.

Sketch of Gaston Planté

Despite being created by French physician Gaston Planté in 1859,[2] over 160 years later over 70%[3] of worldwide rechargeable battery energy storage is lead-acid. The lead-acid battery is still widely used all over the globe because they are

  • inexpensive and simple to manufacture, low cost per watt-hour.

  • Low self-discharge; lowest among rechargeable batteries

  • High specific power, capable of high discharge currents

  • Good low and high temperature performance.

  • Around 99% recyclable.[4]


  • Low specific energy; poor weight-to-energy ratio

  • Slow charge: fully saturated charge takes 14-16 hours

  • Must be stored in charged condition to prevent sulfation

  • Limited cycle life: repeated deep-cycling reduces battery life

  • The flooded version requires watering

  • Transportation restrictions on the flooded type

  • Not environmentally friendly, if improperly recycled.[5]

How are Fire Curtain batteries replaced?

All Fire Curtain systems are subject to 6-monthly inspections which include a full check for all component parts, including the two internal batteries. The batteries will be checked, and if they need replacing, the associated battery and engineer costs are included within the Adexon® 2-year Scheduled Maintenance & Servicing (SMS) package. The 2-year SMS package is encouraged as 1-, and 3-year packages can result in battery replacement being forgotten or overlooked, resulting in increased servicing prices due to the increased likelihood of emergency call-outs.

1. Arrive at site, participate in appropriate safety inductions, and/ or contact site contact and sign in.

If entering an active site, all engineers, tradespeople, and subcontractors will undergo a full safety induction. If entering a building, engineers will locate their site contact and sign in.

2. Identify the correct Fire Curtain

If the batteries are replaced on a curtain not specified by the work order, then the original work order will have to be completed at another time, leaving the engineer liable for the cost of two replacements. This also leaves the original Fire Curtain without working batteries, increasing the danger to life if a fire should occur.

3. Layout tools prepare ladders or MEWPS

Laying out equipment and setting up ladders or Mobile Elevating Work Platforms (MEWPS) will take a small amount of time but will stop unnecessary interruptions to the replacement further down the line if, for example, fixings or parts are missing.

4. Shut off mains power to the control panel using a fuse spare.

Engineers can also stop power running through with the use of a breaker, or a switch, depending on the Fire Curtain type.

As with all electrical machinery, care must be taken to ensure power is off to avoid sometimes fatal injury and accidents with parts.

At this point, the Fire Curtain will descend using the gravitational fail-safe.

5. Allow the transformer to lose power.

Transformers within the system hold power for around 10-15 minutes after the system is removed from mains electricity. If it is not allowed to drain away, it can short circuit the control panel, an error that involves replacing the entire control panel, which is much more expensive and time-consuming.

Your engineer will now be able to replace the battery safely.

6. Use a socket screwdriver to remove all fixings and the covering faceplate.

Fire Curtains come in a variety of styles and have a variety of fixing types, so your engineer will remove what is necessary for your Fire Curtain type.

Example of a socket screwdriver set.

Example of a socket screwdriver set.[6]

Removing these fixings and faceplates allow access to the batteries inside the control panel.

7. Remove batteries

The batteries can now be removed by unclipping the wires that attach them to the control panel.

These wires connect one battery to the other and connect to the battery terminals (the red and black metal sections below.)

Simplistic diagram of the inside of an Adexon lead-acid battery, with the battery terminals marked in red and black.

8. Install new batteries

Engineers will be sure to reconnect the wires and battery terminals correctly.

9. Reinstall fixings and faceplate.

This will cover the batteries back over, keeping them out of sight, and therefore safer when internal buttons are used.

10. Re-energise the system

At this point, all mains power will be allowed back into the system and power will run through again in a loop.

11. Reset the Fire Curtain limits and recommission the system

At this point, the bottom, middle, and top limits of the curtain will be set, and a full check will be completed of all Fire Curtain operations.

If these limits were not reset, then although the curtain would be functional, the batteries would be working, but the curtain would not move. Similarly, the full check of all Fire Curtain operations allows the engineer to be sure that the Fire Curtain is fully operational and can save lives in a fire.

Staff image of a Fire Curtain over a set of lifts.

Replacing the batteries will take around 1-2 hours, depending on the individual Fire Curtain, but does not include travel time or the time it takes for the engineer to take the old batteries to battery recycling facilities, as lead-acid batteries can be harmful to the environment if disposed of incorrectly.

It is increasingly important for clients to understand that the cost of DIY-ing Fire Curtain battery replacement brings with it a high chance of damage, and consequences that are likely to be dangerous.

The last person to touch a Fire Curtain is responsible for it, and when the consequences are a loss of life, the risk versus the proposed savings seems a poor trade-off.

Especially if the servicing and replacement of the batteries are already included in the cost of Adexon 2-year Scheduled Maintenance and Servicing.


[1], ‘How a lead-acid battery works,’ by Bill Hammack, Department of Chemical & Biomolecular Engineering, University of Illinois, published 03.07.2017, <>

[2] Image of Gaston Planté from Encyclopædia, ‘Gaston Planté,’ <> 15.02.2022

[3], ‘The Lead-Acid Battery’s Demise Has Been Greatly Exaggerated,’ by Robert Rapier, published 27.10.2019, <>

[4], ‘The Lead-Acid Battery’s Demise Has Been Greatly Exaggerated,’ by Robert Rapier, published 27.10.2019, <>

[5] Battery University. Com, ‘BU-201: How does the Lead Acid Battery Work? ‘updated 21.10.2021 <>

[6], ‘Metal Socket Driver Wrench Screwdriver Hex Nut Key Nutdriver Hand Tool,’ <> 22.02.2022

Cover image from, courtesy of Hilary Halliwell

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