Douglas Krantz - Technical Writer - Describing How It Works

Are Dead Fire Alarm Batteries Dangerous?

By themselves, dead batteries usually aren't dangerous. However, whatever caused the batteries to die in a fire alarm panel is concerning and needs to be checked out.

Are Dead Fire Alarm Batteries Dangerous?

Greetings Douglas,

I replaced a pair of 12V 7AH Batteries four days ago in an older Fire Alarm Control Panel (FACP). Today batteries were completely dead, no voltage or amp hours. What causes that? Is that dangerous?

Thank you, JM

Several Issues:
  • The batteries are needed in case there is a power blackout. As long as there is no blackout, the batteries aren't needed. But then, blackouts are difficult to predict, so batteries are needed, just in case.

  • The Amp Hour rating printed on the side of the battery is the size of the container. The 7 Amp Hour batteries, when they are fully charged, are capable of providing 1 amp of electrical current for 7 hours. If your fire alarm system is using less current, the batteries will last longer; if your fire alarm system uses more current, the batteries won't last as long.

  • The temperature of the batteries is important. Feel the temperature with you hand. If the batteries feel warmer than the case of the fire alarm panel they are in, the batteries are using more current than the should. The batteries may be bad, or the panel may be bad. If the panel is bad, the panel is overcharging the batteries and the panel may need replacement. If the batteries have been overcharged, they also need replacement. Call your fire alarm service company to check it out.

  • Miswiring the batteries can cause the panel to burn out or blow fuses. Make sure the batteries are wired correctly. I have found miswired batteries that required proper wiring after someone else had put them in wrong. Everyone seems to make that mistake once in a while. If the batteries had been miswired, they might have done some hidden damage to the panel. This should be checked out by the fire alarm service company.

  • If, after confirming that the batteries are wired correctly, the battery voltage is down to zero for any reason, the panel is probably bad. Also, if the batteries are drained to zero volts, the batteries are now bad (they just can't handle being drained too far). The panel and batteries should be checked out by the fire alarm service company.

The service representative from the fire alarm service company has experience to look for hidden clues about the problems. Call the service company, calling them now will save headaches later.

Douglas Krantz
Mr. Krantz

Yes, that was helpful.

Thank you, JM
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