No Battery Trouble on FACU or FACP

Remove Fire Alarm Battery Trouble

Before you read on please be advised that this tactic is only to be used in training FACU / FACP applications.  It is not the intention of Fire Alarms Online to provide this information to eliminate the need for battery backup on a FACU Fire Alarm Control unit, MNS Mass Notification System, RPS Remote Power Supply, etc.

FACP is Normal without Batteries WOW!

There is a way to connect an FACU Fire Alarm Control Unit without backup batteries and have it remain in the normal condition.  Now like I mentioned above, this is typically only used if you have a training and or demonstration FACU that you travel with.  You can also use this trick if you have a redundant FACU in your shop used for training (only if the system is not an approved life safety system for the site).

The backup battery charger on an FACP, FACU, MNS, RPS, etc. is always looking for 24VDC.  This is how it supervises the backup batteries.  In other words, this is how the fire alarm control unit knows that backup batteries are present.  The same terminals on the charger, also put out 24VDC in order to constantly charge the backup batteries so that they are always ready in the event of primary power loss.

FACU Backup Battery Requirements

Most jurisdictions require 24 hours of standby and 5 minutes of alarm for a horn/strobe system and 24 hours of standby and 15 minutes of alarm for a voice system.  See here for battery backup calculations.

With the use of one simple diode, you can accomplish this feat.  Simply place the Anode (+ Solid Black) side of the diode into the non-resetable positive 24VDC power output on the FACU / FACP.  Now place the Cathode (- Stripe) side of the diode into the positive terminal of the backup battery charger.

How this works:  Think of a diode as a one way gate.  Electrical current can flow through it in only one direction.  So this trick is actually quite simple.  The diode is providing a positive current path from the +24VDC output on the panel FACU / FACP and into the + terminal of the battery charger thus tricking it into believing there are backup batteries in place.  The reason for the diode is very important.  You need to remember that the battery charger puts out 24VDC as well.  With that said, we need to block that power from coming back into the +24VDC output on the FACP / FACU.  Here is a picture to help explain this trick on how to keep an FACP / FACU in the normal condition without backup batteries.


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When Are Fire Alarm Batteries Required to be Replaced

What is the Code for Replacing Fire Alarm Batteries?

It is common knowledge in the fire alarm installation industry that fire alarm batteries are to be replaced typically within 4-5 years from date of manufacturing. What you will commonly notice with companies is a lack of experience resulting in dead fire alarm batteries. Most fire alarm technicians will simply take a label maker or Sharpie and write down the installation date on the backup fire alarm batteries.

You may ask yourself, "What's wrong with this?"

The answer is simple. As stated above the the fire alarm batteries must be replaced with 4 - 5 years from date of manufacture. If you write the installation date on the batteries then you are not noting accurate information. The reason for this is that there is no telling how long those fire alarm batteries sat in your warehouse or even the manufacturer's warehouse.

What's the Correct Way to Note the Battery Date?

Fire Alarm Back-up battery manufacturers are stamping the fire alarm batteries with the month and year of manufacture. This is the date that you want to mark down.  The fire alarm battery pictured above is manufactured by Power Sonic and has a date tamp of 10194-H on it.  I wont go into too many details about battery date codes as I have another files to assist you with this.  The code of 10194 = the Month (10) the Day (19) and the Year (2004). So as you can see by a technician labeling the batteries new on "2/2/2015" throws things off a bit.  If you want to download our multi-tool with voltage drop calculations, battery calcs, dB loss and battery date codes, click here.

For your reference I have included the NFPA 72 2013 edition code sections below:

Table 14.4.3.2 #9  Fire alarm batteries shall be replaced in accordance with the recommendations of the alarm equipment manufacturer or when the recharged battery voltage or current falls below the manufacturer's recommendations.

10.6.10.1.1 When the fire alarm batteries are not marked with the month/year by the manufacturer, the installer shall obtain the date code and mark the batteries with month/year of battery manufacture.

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