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How to Test Emergency Light Batteries

Dec. 30, 2021

It is critical to ensure that your emergency light batteries are working properly. In emergency lights that use multiple batteries, they must all be in good condition. One bad battery can affect all the others, shortening their life and increasing future costs.

How to Test Emergency Light Batteries

To test your batteries, you will need:

⊚ a pen and a piece of paper

⊚ a marker (if you have more than one battery)

⊚ a battery from the emergency light unit

⊚ a calculator

Starting with the first emergency light, remove the batteries. Do not try to remove all batteries from all lighting units at once, as you will be unclear which batteries belong to which units. The importance of this will soon become apparent.

If the emergency light has more than one battery, number each one with a marker, making sure not to overwrite any labels with voltage or ah/mah specifications.

Now pick up your multimeter and make sure it is set to measure amp hours or milliamp hours according to the battery specifications. Connect the multimeter to the battery (red lead to "+", black lead to "-") and write down the battery number and ah/mah reading.

Repeat this for all batteries in the lighting unit and compare the reading to the ah/mah on the battery label. If there is a difference, this only indicates that the battery is not fully charged. This may not be a concern, but further checks should be made.


For each battery, calculate the charge level as follows.

(multimeter reading/battery label specification) * 100 = percentage charge

So, for example, if an emergency light battery has a 2,000 mAh label and the multimeter reads 1,500 mAh, the charge level would be

(2,000 / 1,500) * 100 = 75%

If any emergency light battery is less than 50% it should be replaced.

Write down each percentage on a piece of paper and compare them to each other. If any one of them differs from the others by more than 10 percentage points, they should be replaced.

It is important to understand this here, if you replace one, it will read close to or at 100%. For example, if the other batteries are at 75%, they will damage the new battery and shorten its life, so in this case it is best to replace all the batteries in the battery pack.

Repeat this process for each emergency light.


If you are unsure of your results, please contact Godson Technology for assistance.

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