How we choose the emergency light battery
All emergency lights and illuminated emergency exit signs use batteries to power the lights. To ensure the continuous readiness and operation of the emergency lights, these batteries are rechargeable. The circuitry within the emergency lights both charges the batteries and ensures that they remain charged.
Types of batteries used in emergency lights
There are two types of batteries used in emergency lights：
1. Sealed lead-acid batteries (same type as for cars)
2. Nickel-cadmium batteries
Sealed lead-acid batteries are the oldest rechargeable technology. They are called lead-acid because they contain lead alloy plates that are immersed in acid. The acid breaks down the plates and produces electrons that are charged, i.e. electricity. More recently, the technology of lead-acid batteries has been improved to allow for fully sealed cells that do not require the addition of water to maintain the acidity.
How we choose the emergency light batteries
The two types of rechargeable batteries used for emergency lighting equipment each have their own advantages and disadvantages.
Advantages of lead-acid batteries.
l Lowest cost
l Better heat and cold resistance
Disadvantages of lead-acid batteries.
l Larger size
l Heavier weight
l Must be kept upright
l Damage due to "deep cycling" (loss of battery charge)
Advantages of NiCd batteries.
l Smaller size
l Lighter in weight
l Can be oriented in any direction
l Longer life
l Susceptible to extreme heat and cold
Disadvantages of NiCd batteries.
Higher cost
Must be fully discharged at regular intervals (annual testing will deal with this issue)
Has a "memory", if it is not fully charged the first time, it will never accept a full charge
Typically, lead-acid batteries are used for emergency lights with steel housings and NiCd batteries are used for emergency lights with thermoplastic housings.
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