Emergency lights are critical safety devices found in many commercial, industrial and large residential buildings, as well as some private residences. They are designed to provide at least 90 minutes of light in the event of a power outage, allowing a building's staff, customers or residents to exit the building safely during an emergency. They also help first responders by providing illumination that allows them to check the building for any remaining occupants.
Emergency lights fixtures feature a set of energy-efficient lights, a battery to provide electricity when the main power goes out, and a charging system that recharges the battery when the main power comes back on. Over time, the batteries in emergency light fixtures will slowly lose capacity, or fail completely, preventing the lights from lasting for a full 90 minutes during a power outage. In most cases, the emergency light batteries are easily replaceable, and where the fixtures are required by local codes, they must be replaced as soon as possible.
There are many types of replacement emergency light batteries available, and here are a few of the qualities you should look for when choosing replacements:
#1 A Reasonable Cost
When replacing emergency light batteries, or any other type of rechargeable battery, cost is an important consideration. Choosing the least expensive replacement may not always be the best choice, as it could have a lower capacity, substandard materials and construction, or generally poor performance. Likewise, choosing a battery made by the original manufacturer also may not be the best choice, because they are often priced higher than equivalent batteries from quality third-party suppliers. The best solution is to do some research and choose a battery from a reputable third-party manufacturer that meets or exceeds the specifications of the original at a reasonable cost.
#2 The Correct Battery Type
Emergency light batteries are available in several different chemical formulations, including sealed lead acid (SLA), nickel cadmium (NiCad) and nickel metal hydride (NiMH). Each formulation has specific charging characteristics, strengths and weaknesses. In general, it is best to choose the same type of battery as the one that was originally installed, though in some cases, NiCad and NiMH batteries can be interchangeable. Additionally, emergency light batteries may be available in standard packages, such as AA, C or D-sized cases, as well as custom packages that combine multiple cells into a single unit. Be sure to choose the right package for your fixture, and make sure that it has the correct type of terminal connections.
#3 The Proper Voltage
Emergency light fixtures operate at a range of voltages, including the popular 6-volt and 12-volt systems, as well as systems that operate at 1.2, 2.4, 4, 4.8, 7.2 and 9.6 volts. Make sure that the replacement batteries you choose have the same voltage range as the originals. If a battery with an incorrect voltage rating is used, the battery, the fixture or the charging system could be damaged permanently, or it could create a fire risk.
#4 A Comparable Capacity
Battery capacities are measured either in amp-hours (AH) or milliamp-hours (mAH), which represents the amount of energy that can be delivered over a set time period. Theoretically, a 10 AH battery can deliver 10 amps of power for one hour, or 1 amp of power for 10 hours. However, in real-world conditions, many factors can affect the amount of power that is actually delivered.
Larger loads will deplete the battery at a quicker rate, so a 10 AH battery may only be able to provide 10 amps for 45 or 50 minutes. Cold temperatures can also reduce the performance of batteries, and as batteries age, they will lose capacity permanently. Finally, SLA batteries and other lead-based batteries should never be depleted more than halfway, otherwise their lifespan can be reduced dramatically. This makes the usable capacity of a 10 AH SLA battery about 5 AH.
To ensure that your emergency lights perform as expected, choose replacement batteries that have the same amp-hour rating, or higher. If you choose a battery with a greater capacity, be sure that is will physically fit in the fixture.
#5 Quality Components
A few third-party manufacturers may cut corners during the manufacturing process, using substandard materials and components in their emergency light batteries. This may include low-purity lead alloys for SLA batteries, poor-quality plastics for the battery cases, or aluminum wiring instead of copper. For the best performance, choose a reputable brand of battery that uses only quality components which meet or exceed the specifications of the original battery.
#6 A Reasonable Warranty
Many battery manufacturers offer some type of warranty, which will typically range from a few weeks to a year. High-end batteries may even carry multiple-year warranties. These warranties, however, are typically pro-rated, which means that if a refund is granted under the warranty, it will be a fraction of the original purchase price, according to the age of the battery. Many warranties will also be rendered void if the battery is installed incorrectly, used improperly, overcharged, undercharged or otherwise abused. Be sure to read and understand the warranty for your emergency light batteries, if one is offered, and that you follow its provisions closely.
Caring for Your Emergency Light Batteries
Like all types of rechargeable batteries, emergency light batteries will experience a level of self-discharge over time, requiring periodic recharging, and some batteries, like SLA models, can be damaged if they are stored for long periods without recharging. Once a month, the emergency light fixtures should be tested to make sure that they last a full 90 minutes. This is done by unplugging them or shutting off the breakers that provide power, and allowing them to run until they shut off. After the power is restored, the batteries will be recharged fully,which will help extend their lifespan. Also, be sure to inspect the battery connections periodically, and make sure they are clean and tight.
By choosing emergency light batteries that feature these six qualities, and ones that are made by a quality third-party manufacturer, you can save money and be sure that your emergency light fixtures will operate as expected when the power goes out.