Why Your Emergency Lights Fail

Building managers frequently ask us why their emergency lights fail after just 2-3 years. The most common issue is that the battery can't hold enough charge to power the lights for the required 90 minutes, as specified by AS/NZS 2293.2:2018. This article delves into the factors affecting battery life, the evolution of battery technology in emergency lighting, and practical tips for replacing and disposing of batteries.

Causes of Battery Degradation

Battery life can be influenced by several factors. Here's a closer look at the most important factors that affect emergency and exit lighting:

• Age: Batteries naturally degrade over time, a process known as calendar degradation. Factors like high operational temperatures and prolonged storage at very low charges can accelerate this degradation. Age is the most significant factor in the degradation of batteries used in emergency and exit lights.
• Initial Energy Capacity: Batteries gradually lose their energy capacity over time. A larger initial energy capacity means that the emergency light can maintain the required 90-minute discharge duration for a longer period, even as the battery degrades.
• Rated Cycle Count: While the rated cycle count is important for most electronic products, it is relatively insignificant for emergency lights. This is because emergency lights are typically discharged only twice a year. Over a ten year period, an emergency light may go through fewer cycles than a mobile phone does in a month.

What Batteries are used in Emergency Lights?

Initially, emergency lighting systems relied on large, heavy lead-acid (Pb) batteries, which were not very energy-efficient and required frequent replacement to remain effective in emergencies. Manufacturers then transitioned to Nickel-Cadmium (Ni-Cd) batteries, which were smaller, more energy-dense, and capable of handling higher temperatures, often lasting 2-4 years under optimal conditions. This allowed for smaller and more compact emergency lights and exit signs but at the cost of environmental impact due to the toxic cadmium in disposed batteries.

In the 2000s, Nickel-Metal Hydride (Ni-MH) batteries began to replace Ni-Cd batteries. Despite Ni-MH batteries being more expensive, they offered better energy density, better frequency in discharge cycles and slightly improved environmental credentials, with a lifespan of 3-5 years.

Over the past seven years, Lithium Iron Phosphate (LiFePO₄) batteries have emerged as the preferred choice, replacing Ni-MH batteries. These batteries offer even higher energy density and much greater voltage stability leading to much more stable and longer shelf-life when not in use, as well as being much more environmentally friendly, containing no toxic metals or carcinogens. Due to their better chemical composition and stability, these batteries typically use only one cell, leading to long lifespans of 5-12 years, low toxicity, and easy recyclability. LiFePO₄ batteries are now considered the modern standard and the optimal choice for emergency lighting.

Considering all these advantages, all of our products exclusively use LiFePO₄ batteries to ensure maximum life expectancy.

How long do Emergency Light Batteries Last?

Lithium Iron Phosphate (LiFePO₄) batteries typically last between 5 to 12 years in most modern emergency and exit lights. To maximize battery life, aim to keep your emergency light in an environment with temperatures between 20°C and 25°C.

When selecting an emergency light, we recommend opting for models with single-cell batteries. This design minimises the risk of failure, as multi-cell batteries can be compromised if just one cell malfunctions. Additionally, consider the battery capacity of your emergency lights. For example, our Sunrise LED recessed emergency light features a 10.5 Wh battery, ensuring over 4 hours of reliable power, well above the minimum requirement of 90 minutes.

Repairing Emergency Lights

Traditionally, the industry practice has been to replace the entire emergency light fitting when it fails the six-monthly and annual testing. However, with proper diagnosis, often the only component that needs replacement is the battery, providing a significantly cheaper alternative.

Replacing Emergency and Exit Light Batteries

AS/NZS 2293.3:2018 Section 4.9b states that emergency lights must be marked with necessary information to ensure correct replacement of the batteries.

This information is typically located on the battery itself. You can use the battery model number to either search online to find a reseller, or alternatively visit your local electrical wholesaler to see if they are able to order it in for you.

Can Anyone Replace an Emergency Light Battery?

In a self-contained emergency light where the battery is inside the fitting, only electricians can change the battery. However with our Bondi emergency batten, replacing the battery is easy thanks to our Kwicky replaceable emergency module. This self-contained module allows for safe battery replacement without needing to power down the electricity supply.

How to Dispose of Old Emergency Light Batteries

For environmental and safety considerations, emergency light batteries should never be discarded with general waste. Instead, they should be taken to a specialised recycling facility where they can be safely dismantled, and valuable metals recovered.

Elumen has partnered with EXITCYCLE, a program initiated by Lighting Council Australia, to help recycle emergency light batteries. As a signatory, we are helping collect any Elumen or WBS branded emergency light batteries at our Silverwater warehouse for recycling. To dispose of your batteries responsibly, contact us, or visit us at our warehouse.

Conclusion

Choosing the right emergency lighting technology can significantly impact safety and maintenance costs. With advancements in LED and battery technology, modern emergency lights can provide reliable service for many years. For the best performance and longest lifespan, consider Elumen's products with LiFePO₄ batteries.