Replacing FACP Batteries

 Replacing FACP 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.

The 2007 NFPA72 shows in Table 10.4.4, Item 6(d)(1), that the sealed lead-acid batteries used for battery backup in fire alarm systems need to be replaced within 5 years of manufacture. The NFPA wants the batteries replaced because the battery capacity is down to about 80% by that time.

Battery capacity, the amount of amphours in a battery, changes over time. In the first few months after manufacture, the amphour capacity of the average battery increases a few percent. For several years, this capacity doesn't change much. Near the end of the battery's useful life, the amphour capacity starts to taper off. At 5 years, it's down to about 80% of rated capacity.

If the NFPA requires replacement at 5 years, why do most fire alarm service companies replace the batteries after 3 or 4 years?

For your reference I have included the NFPA 72 2019 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.

CALCULATING BATTERY STANDBY REQUIREMENTS:

In most instances, the manufacturer provides a form for you to utilize in calculating the size of the battery required.  I strongly advocate that you cross-check the number this yields with an actual empirical measurement utilizing a good quality meter.  I would not recommend using the clamp-on style meter for this.  Here’s the correct method for measuring standby and alarm current of a conventional (or addressable) fire alarm panel (with no EVCS system):

1. Disconnect the jumper between the two batteries that normally form the 24VDC supply.  The fire alarm system should annunciate a trouble condition.  (This also happens to be part of the testing criteria!)
2. Set your multi-meter for “DC AMPS” and ensure the leads are connected properly.
3. Clamp the RED (positive) lead to the RED (postive) terminal that the jumper you removed in step 1 was connected to.
4. Clamp the BLACK (negative) lead to the BLACK (negative) terminal that the jumper you removed in step 1 was connected to.
5. The fire alarm trouble indication should clear and the system should appear “normal” in all respects.  The current you see displayed is the nominal charging current being output to the battery (it should appear as a “negative” number if you’ve connected everything properly).
6. Turn off the circuit disconnect means to the fire alarm system.  The ammeter should now display the system’s supervisory current (a positive number).  DON’T SILENCE THE TROUBLE INDICATION JUST YET!
7. Turn off the circuit disconnect means to the sprinkler heat trace controller (if provided).  The reason for this is that we are simulating a power failure to the building which means the fire alarm panel should display all associated troubles and supervisories in order to accurately measure the supervisory standby current.
8. If your meter is equipped with a “MAX/MIN” setting, engage it and wait for the display to stabilize at the highest current reading.
9. Record the reading on your test report.
10. Initiate an alarm on the fire alarm system by triggering a device or zone.  Wait for the reading to stabilize.
11. Record the alarm current reading on your test report.
12. Silence the alarm and trouble signals.
13. Turn off the “MAX/MIN” setting on your meter.
14. Restore power to the heat trace controllers.
15. Reset the system.
16. Restore power to the fire alarm system and observe the charging voltage.  It should read higher than the nominal charging voltage you recorded earlier.  This is normal.  You will observe that this reading will drop gradually as the system stabilizes and should return to the nominal reading you first observed.
17. Remove the meter’s leads and restore the connection through the battery jumper you removed in step 1.  (Don’t forget to move the meter leads back to the normal “voltage” slot on your meter!)
18. Take the supervisory current you recorded and multiply by twenty-four.
19. Divide the alarm current by two (if the Code requirement is for 30 minutes of alarm time).  Multiply the alarm current by two (if the Code requirement is for two hours of alarm time).
20. Add the results of step 18 and step 19 together and multiply by the manufacturer’s recommended de-rating factor (this is commonly “1.2”).
21. Compare this with the results you’ve obtained by using the manufacturer’s battery standby calculation form.
22. Round up the number you get in step 20 if it’s more than the number you calculated in step 21 (otherwise use the number you obtained in step 21).  This is the MINIMUM battery capacity for the system under test.

BATTERY SIZE REQUIREMENTS AND MAINTENANCE:

These panels require a 24 volt gel-cell battery for proper operation. 24 hours of standby power is required for Local Systems and Central Station (NFPA-72).

The chart below will assist you in selecting the proper size battery: (Does not include LED Annunciator)