Batteries For Fire Alarms

[Davro]

I Service Alot Of Fire Alarms But Some Of The Fire Alarm Batteries Have No Date On Them Or Any Reference In The Log Book To Any Date When They Are Installed. I Know As A Rule Some Batteries Are Good For 4 Or 5 Years And I Test Them Every Visit But When Do You Think I Should Install New Ones, Within The Recommened Life Or Now As Good Practice.

[JonnyG]

If the batteries aren't marked with a date, I think it would be fair to assume that they have been installed since the commissioning.

Standby Batteries should be changed every 5 years.

What are you testing the batteries with?? Have you done a load test??

[Benzerari]

I Service Alot Of Fire Alarms But Some Of The Fire Alarm Batteries Have No Date On Them Or Any Reference In The Log Book To Any Date When They Are Installed. I Know As A Rule Some Batteries Are Good For 4 Or 5 Years And I Test Them Every Visit But When Do You Think I Should Install New Ones, Within The Recommened Life Or Now As Good Practice.

If the current still above 70% of the one prescribed on the batteries that would be fine, if less than that you should change the batteries and label them with the new date...

Usually the current gets down before the voltage does, that is why some times you measure 12Vdc still OK but in fact there is NO enough current drawn through the load (panel, cabling and devices). That's why I think you need to test the current drawn better of with the battery tester...

Also if one of the set is less then 70% of the value prescribed on the battery, it is better of changing both of them by brand new ones.

If I am wrong feel free to correct me Guys

[John Dragon]

We change all batteries at 4 years.
Often earlier if they fail to reach the required capacity when tested.
If no date on them, then you must assume that they are  out of date (what else would you do, just make up an installed date?)

[Galeon]

Allowing for all the comments above , older battries wont have the label showing non disposal in  a normal refuse bin.

[Wiz]

The reading of a battery voltage as an indication of it's condition is worthless unless a load is applied to the battery.

25 years of experience of testing Sealed Lead Acid batteries has provided a simple and fairly accurate testing proceedure that allows me to ascertain the condition of a battery using discharge rate/time

The discharge load should be approx 5/10% of the batteries capacity i.e 350-700mA for a 7AH battery or 600-1200mA for a 12AH battery etc. etc.

With the load applied and discharging the battery, the battery voltage should be monitored for a period of time up to approx. 30 minutes. If the battery voltage drops below approx 95% of it's nominal voltage within 15 minutes or below approx 90% in 30 minutes then it should be considered that the actual capacity of the battery is not sufficient and the battery should be replaced.

There are a number of automatic testers available that carry out a similar process to the above (and include the effect of ambient temperature) and provide an actual approximate actual battery capacity remaining figure.

BS 5839 part 1 recommends that only batteries with an expected life of at least 4 years, under the conditions for which they are being used, are installed in fire systems and that batteries should be clearly labelled, and where the label can be seen without disturbing the battery, with their date of installation.

BS5839 Part 1 recommends that at every serivce visit the batteries are examined and load tested to ensure that they are in good serviceable condition and not likely to fail before the next service visit.

BS5839 part 1 does not recommend a definite battery replacement schedule based on time in use. I presume this is because it is possible to purchase batteries with longer predicted life cycles than 4/5 years or that suitable operating conditions might allow even 4/5 year life batteries to operate longer.

However it would make sense to replace any battery before the end of the life predicted by it's manufacturer or at 4 years (if predicted life is not known) because I can't see how anyone could say that the batteries were otherwise 'not likely to fail before the next service visit'

Obviously batteries that fail an inspection/test despite being less than the  manufacturer's predicted life, should be replaced as a matter of course.

[Benzerari]

BS5839 part 1 does not recommend a definite battery replacement schedule based on time in use. I presume this is because it is possible to purchase batteries with longer predicted life cycles than 4/5 years or that suitable operating conditions might allow even 4/5 year life batteries to operate longer.

.

I think this is because of the fundamental variable which is the load, the life cycle is inversely proportional to the load, the bigger the load is the shorter life cycle the battery can have, in addition to others variables that may have negative effects such as temperature… in addition to how long and how many times alarm went off with mains disconnected or failed…. All of these have to be taken into account in order to develop a formula to calculate the life cycle of a given battery… as the service testing and inspection is in charge to determine whether the life cycle is over or not there would be no need then for such calculation to be set out by BS…

[Wiz]

BS5839 part 1 does not recommend a definite battery replacement schedule based on time in use. I presume this is because it is possible to purchase batteries with longer predicted life cycles than 4/5 years or that suitable operating conditions might allow even 4/5 year life batteries to operate longer.

.

I think this is because of the fundamental variable which is the load, the life cycle is inversely proportional to the load, the bigger the load is the shorter life cycle the battery can have, in addition to others variables that may have negative effects such as temperature… in addition to how long and how many times alarm went off with mains disconnected or failed…. All of these have to be taken into account in order to develop a formula to calculate the life cycle of a given battery… as the service testing and inspection is in charge to determine whether the life cycle is over or not there would be no need then for such calculation to be set out by BS…

All of the variables you mention will effect the life of a battery. This is the reason it should be inspected and load tested to ascertain capacity on every service visit. Even if the inspection/load test on the final visit before expiry of manufacturer's suggested life cycle shows a suitable capacity remaining, I would suggest that the battery is replaced anyway on the basis that after expiry, it is harder to argue ignoring the BS recommendation of replacement unless ...'not likely to fail before the next service visit. This is why everyone, these days is told to replace batteries every 4 years (at least). This (sometimes erroneous)advice is actually based on the assumption that the batteries only have a recommended life of 4 years (because BS recommends batteries with a minimum expected life of 4 years). Obviously, they could be 10 year life batteries and if used in the perfect environment they would exceed even the 10 years (at least) and replacing them automatically at 4 years would be a waste of a good battery. However, because the way the BS is written, it would hard to argue keeping them after their 10 year life (even if seemingly good)

The point I'm making is that BS doesn't recommend a maximum life cycle and other earlier postings have mentioned 4 and 5 years automatic replacement where this might actually be unnecessary or conversly give the impression that all batteries will last 4/5 years without any need to test for remaining capcity.

I have found that many engineers just follow one piece of advice that they once heard somewhere (that may have been perfectly relevant for that particular instance) but apply it blindly to every situation. It is more important to learn what the BS recommendations are trying to explain and understand the variations that they might allow. Very few BS recommendations are 'black or white'. There are many shades of grey!

[Davro]

Hey Thanks For The Replys I Do A Voltage Test And And A Milli Amp Test But Never Fully Loaded For 30 Minutes Most Customers Would Get Very Angry With Me So I Will Just Put It Down On The Service Sheet But Yes Your Right It All Depends On The Conditions Because I Went To A Call Out Last Month And They Have Never Had A Service On Their Fire Alarm And The Battery Was 19 Years Old!!!!!! This Was The Reason For The Call Out Since Then They Have It Serviced Every 6 Months By Us Now.

[Wiz]

Hey Thanks For The Replys I Do A Voltage Test And And A Milli Amp Test But Never Fully Loaded For 30 Minutes Most Customers Would Get Very Angry With Me So I Will Just Put It Down On The Service Sheet But Yes Your Right It All Depends On The Conditions Because I Went To A Call Out Last Month And They Have Never Had A Service On Their Fire Alarm And The Battery Was 19 Years Old!!!!!! This Was The Reason For The Call Out Since Then They Have It Serviced Every 6 Months By Us Now.

It would be quite possible to remove the batteries from the panel to load test them. You don't need to use the alarm warning device load to test with.  A suitable resistor or lamp could achieve what you need for a load. If you remove the batteries for a prolonged period you might want to put some good batteries in the panel temporarily to keep the system functioning, although current recommendations actually state the system should operate correctly without any batteries connected.

[Davro]

Very Good Answer Will Do That And Carry On Service  And Come Back To Them In 1/2 Hour Many Thanks

[John Dragon]

Or you could just buy a tester from ACT?

[Wiz]

Or you could just buy a tester from ACT?

Heartily endorsed! For about £150 you get a piece of kit that is sufficiently accurate and gives you a visual display of actual battery capacity in a short time. Furthermore, it is something else that should impress on your customers that they are getting value for the money they are paying for their service. Any service company using manufactured testing equipment always look good!

[John Dragon]

Or you could just buy a tester from ACT?

Heartily endorsed! For about £150 you get a piece of kit that is sufficiently accurate and gives you a visual display of actual battery capacity in a short time. Furthermore, it is something else that should impress on your customers that they are getting value for the money they are paying for their service. Any service company using manufactured testing equipment always look good!

I find it hard to believe that any alarm maintenance company doesn't use ACT IBTs or something similar?
They pay for themselves very quickly by finding failing batteries that would not normally be noticed.

[Benzerari]

I guess so, if the next generation of analogue addressable systems would be able to monitor the most fundamental battery’s variables, current, voltage, internal temperature, ... in addition to the remaining life time according to the existing load.  

Such intelligent software would rule out the need for testing the batteries on site, as it will be possible to check all of those parameters online… through web-based software… but as we are not there at the moment, I would prefer a battery tester…