Exit Sign with Battery Backup: Need,Usage and Working Hour

You’ve probably seen exit signs everywhere. In your office, at the theater, and many more. Contrary to some people’s belief, those signs do not lit up by themselves. They are powered by batteries, and the batteries need to be constantly checked so the sign owners can replace them once the batteries are dead. In this article, we will discuss all we need to know about an exit sign’s battery, from its working hour to backup. 

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Do exit signs need battery backup?

Yes, exit signs do need battery backup, but not without reason. To understand why, it’s important for us to know the importance of exit signs.

If you live in the United States, then an exit sign is a must for your business. Exit lights that work aren't simply a good idea; they're also needed by law. All occupied structures must have authorized Exit signs that are lit and visible from all directions, according to NFPA Code 101.

Not having exit signs can cost you money. Two property management firms and one restaurant owner were fined a total of $101,000 on July 9th, 2012, for fire code breaches, which included the lack of properly functional emergency exit signs.

Your institution must have functional emergency exit signs that conforms with all applicable standards to prevent expensive penalties or, worse, a life-threatening disaster. The majority of exit signs are lighted by incandescent bulbs, and the signs are generally internally connected into emergency backup power to assure continuous lighting in the case of an emergency or power loss.

What batteries do exit signs use?

The light in all emergency lights and illuminated emergency exit signs are powered by a battery. These batteries are rechargeable to ensure that the emergency light is ready and operational at all times. The emergency light's circuit charges the battery and ensures that it remains charged.

The following are the two types of batteries used in emergency lights:

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Sealed Lead-acid Batteries

The earliest rechargeable technology is sealed lead-acid batteries. They're termed lead-acid because they're made of lead alloy plates that have been submerged in acid. The acid dissolves the plates, releasing charged electrons, which are the building blocks of electricity. Lead-acid battery technology has recently advanced, enabling for entirely sealed systems that do not require the injection of water to maintain acid level.

Lead acid batteries are the most preferable batteries since they are lower in cost compared to nickel-cadmium and are more resilient to heat and cold. 

However, it should be noted that lead-acid batteries are the larger out of the two batteries. The size means that it is also heavier. The battery is designed in such a way that it needs to remain upright, and it can get damaged due to deep cycling. 

Nickel-cadmium Batteries

The first “dry” (no acid required) rechargeable batteries were nickel-cadmium batteries. Other technologies have been created since then, although they are typically more expensive. A dielectric (non-conductive) layer separates the two metals in a nickel-cadmium battery, causing the metals to magnetically react with each other, creating the charged electrons that create electricity.

Nickel-cadmium batteries are typically smaller, meaning that they are also lighter when it comes to weight. The battery is also more flexible, meaning that it can be placed in any direction we want. It also lasts longer and is more adaptable to heat and cold.

Unfortunately, the battery is not perfect. It is higher in cost, and we need to take extra attention by discharging it periodically. Nickel-cadmium batteries also have the memory effect, meaning that full charging is not applied to them. 

Which one is better?

Note that the two batteries have their pros and cons. None is better, and everything depends on how we use them. Lead-acid batteries are typically used in emergency lights with steel enclosures, whereas nickel-cadmium batteries are utilized in emergency lights with thermoplastic housings.

No matter what battery we use, one thing is for sure: that we need to take care of them properly. To ensure that the units will operate during a power outage, OSHA (Occupational Safety and Health Administration) rules demand periodic preventative maintenance. Below are the requirements for the extra batteries:

●Able to turn on the sign during an emergency.

●The battery should last for at least ninety minutes.

●Can be purchased at inexpensive price and available for replacement.

●Have voltages and amperages.

●Properly tested and maintained per month and per year according to OSHA regulations.

How long do exit sign batteries last?

In most cases, the battery in an exit sign is designed to last at least 90 minutes in the event of a power outage. The battery is charging when power is supplied to the exit sign. Owners of emergency lights should undertake routine planned maintenance at monthly and yearly intervals, according to OSHA rules. If either the 90-second or 90-minute emergency readiness tests fail (i.e. the lamps don't light up), you may need to replace your emergency light batteries.

Here are the steps to replace the battery:

1. Open up the housing using a screwdriver. The majority of emergency lights utilize a philips head head, however certain vandal-proof luminaires require a specific hex driver bit. Hopefully, when you bought the gadget, you or your maintenance staff saved the bundled bit.

2. You will be confronted with a slew of cables now that the plate has been removed (don't worry, this is typical). Some of these red, black, blue, or white electrical wires will connect the AC electrical conduit to a voltage transformer, which will then connect to the switching circuits. The circuit board is connected to the battery by one, two, or more cables.

3. The battery in your emergency light will be either a sealed lead acid (SLA) or a Nickel Cadmium (NiCd) battery. SLA batteries resemble infant car batteries, but NiCd batteries like regular AAA batteries wrapped in protective plastic shrink wrap. When the leads from the + and - contact points are removed, most batteries will slip out of the device. Some cells will be contained in a harness, which must be removed as well.

Exit sign is a delicate matter that needs to be given extra attention, including its extra batteries. Maintain it regularly, and you are good to go.