Ensuring your emergency light batteries are working correctly is vital and in many states you are required to do so by law. In emergency lights which use multiple batteries they must all be in good condition. One bad battery will affect all the others, shortening their lifespan and adding to future costs.
To test your batteries you will need:
- a pen and paper
- a marker pen (if you have more than one battery)
- the batteries removed from the emergency light unit
- a calculator
Start with the first emergency light and remove the batteries. Do not be tempted to take all the batteries from all the lighting units in one go as you will become confused as to which batteries belong to which units. The importance of this will become clear shortly.
If the emergency light has more than one battery then number each one with the marker pen making sure not to overwrite any label with voltage or ah/mah specifications.
Now take your multimeter and make sure it is set to measure ampere hours or milliampere hours depending on the specification on the battery. Connect the multimeter to the battery (red lead to ‘+’ and black lead to ‘-‘) and write down the number of the battery and the ah/mah reading.
Repeat this for all the batteries in the lighting unit and then compare the readings with the ah/mah on the labels of the batteries. If there is a difference this simply indicates the batteries are not fully charged. It may not be a cause for concern but further checks should be carried out.
For each battery calculate the level of charge as follows:
(multimeter reading / battery label specification) * 100 = percentage charged
So for example if the emergency light battery has a 2,000 mah label and the mutlimeter reading is 1,500 mah the level of charge is:
(2,000 / 1,500) * 100 = 75% charged
If any of the emergency light batteries are less than 50% they should be replaced.
Write down each of the percentages on your piece of paper and then compare them against each other. If any are more than 10 percentage points adrift from the others they should be replaced.
It’s important to understand here that if you replace one it will have a reading close to, or at, 100%. If the others are at, for example, 75% they will damage the new battery and shorten it’s life so it is better to replace all the batteries in the pack in this situation.
Repeat this process for each emergency light.
If you are unsure about your results call Battery Guy toll free on 800-572-1975 for assistance.
what type of meter are you supposed to use?
To check our own batteries we use a very simplistic battery analyzer that simply indicates GOOD, MARGINAL & BAD (DO NOT USE). IT IS GOOD FOR 6V SLA BATTERIES, WHICH IS A MAJORITY OF EMERGENCY LIGHTING APPLICATIONS. YOU SIMPLY CHOOSE 2, 4, 6, 8, 10 OR 12 AH ON THE SCREEN AND HOOK IT UP. IT IS MADE BY STONE TECHNOLOGIES CORPORATION, MODEL 612A.
FOR ALL OTHER BATTERIES WE USE A SIMPLE INEXPENSIVE VOLT METER AND MEASURE VOLTS. FOR EXAMPLE, A 12 VOLT BATTERY SHOULD READ ANYWHERE FROM 12V AND A LITTLE HIGHER WHEN NEW. If IT MEASURES UNDER 12V, TRY TO INSTALL IT IF IT ISN’T ALREADY AND SEE IF IT WILL CHARGE BACK UP. IF THIS BATTERY HAS BEEN IN USE IN A FIXTURE AND MEASURES UNDER 12V, YOU DON’T HAVE MUCH TIME UNTIL IT IS BAD. THIS ISN’T AS EXACT, BUT SEEMS TO WORK JUST FINE.
THERE ARE ALSO OTHER BATTERY ANALYZERS OUT THERE THAT ARE EXACT, BUT THEY CAN COST INTO THE $1,000’S OF DOLLARS AND REQUIRE QUITE A BIT OF PROGRAMING FOR EACH SPECIFIC BATTERY. YOU CAN FIND THESE ONLINE.
ANOTHER THING TO CONSIDER IS THAT MOST EMERGENCY LIGHTING FIXTURES NOW COME WITH A TEST BUTTON THAT WILL INDICATE GOOD OR BAD.
HOPE THIS HELPS