Can you replace batteries in emergency lights?


Almost all self contained emergency lights have a battery that are designed to be replaced. They are designed to last about 4 years, with regular testing which actually does the battery some good. There are many factors that affect the life of a battery, that is why regular testing is a must.

Extremes of heat and cold for prolonged periods can dramatically reduce the life of the battery. This could mean that you are changing the battery in your emergency light more often.

Types of batteries

Selection of Emergency Lighting Batteries
Different types of batteries

Throughout the years battery technology has advanced quickly. This makes it hard to pinpoint exactly what battery you have in your emergency light. Typically, emergency lights come with:

  • NiCd – Nickel–cadmium
  • NiMH – Nickel–metal hydride
  • LiFePO4 – Lithium iron phosphate

All batteries will have identification on them. It is important to match like for like when replacing them. This is because the charging control circuit will have been designed to charge that specific type of battery. If you replace with a different type of battery it will probably damage it. They all charge slightly different.

Also, note the configuration the batteries are packed in. From the picture above you can see a 5 cell D pack, a 6 cell D stick and two 3 cell sticks type C and sub C. The way they are arranged is only important when fitting inside the emergency light. A 3 cell pack would be the same as a 3 cell stick.

Tip: You simply order the exact same battery type and shape that you have when replacing the battery.


The replacement battery will be secured in the same way as the old one. This will be either via battery end caps or perhaps screwed or zip tied into the fitting. Either way it is important to secure the battery inside the emergency light. This is because they are relatively heavy and could damage the control gear if not secured.

Is it a battery?

At the start I mentioned that most self contained emergency lights have replacement batteries. If you have a central battery system then the actual lights are not classed as self contained. Their battery is in another part of the building and not inside, so that rules them out. However we now have some self contained emergency lights that use supercapacitors.

Supercapacitors are not batteries and are generally not replaceable and you probably wouldn’t need to either. We use supercapacitors in our emergency lights for cold stores. This is because they can tolerate much lower temperatures and can last 10 years +.

Do I have to be qualified?

Bulkhead Battery Connection

No. But you should be competent with working with wiring. First thing, ensure there is no power supplying the fitting, if your unsure on how to do this talk to your electrician. Then it should be a simple procedure of unclipping the old battery and removing from the fitting then reversing the steps to put the new one back in.

Once the fitting is back installed restore the power and check that the green charging light is illuminated.

Additional Reading…
When to Test Emergency Lights
How to Test Emergency Lights

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