How we choose the emergency light batteries?
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 Ni Cd 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.
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.
The batteries used in emergency lights are also available in a variety of voltages from 6 VDC to 24 VDC. higher voltages allow brighter lights to be connected to the emergency light. They also work better in situations where remote light heads need to be connected to the emergency light unit, as there will be less voltage loss over the line distance. Finally, higher voltage batteries also allow the use of higher wattage bulbs, which further increases the light intensity.