Home alarm system SLA sealed lead acid battery replacement interval

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rosnic0

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#1211123 9-Jan-2015 13:56

I have installed and setup quite a few Bosch alarms ICP-CC488 model although the fault analysis is probably similar on the other models too.
Has the keypad fault light come on?
If so you can look up details of the fault, using the keypad and this is how
1/ Press and hold the (5) key until 2 beeps are heard and stay & away begin flashing.

     One of the zone lights 1-8 should be on as well.
In your case zone 1 should be lit indicating a (system fault)

2/ Press and hold button (1)   [on my panel I don't have to hold it]

     Now the numbers lit indicate the fault/s

      1= Battery Fail
      2= Date/Time
      3= RF Rx jamming, tamper or comm's fail
      4= Horn speaker fail
      5= Telephone line fail
      6= Eeprom fail
      7=Aux power supply fail
      8=AC fail

3/ Press (#) key to exit

So you can keep an eye on your own battery and replace it yourself when it fails the test.

Ross

timmmay

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#1211126 9-Jan-2015 14:00

Thanks Ross. My system uses a similar coding/control system, maybe the same one. My battery isn't reporting any problems - does it report a problem when the battery is completely dead or when it still have some life in it but it's time to replace it?

rosnic0

4 posts

Wannabe Geek

#1211179 9-Jan-2015 14:44

I'm not sure what constitutes a fail on the battery test Timmmay but I assume it'll be done by monitoring terminal voltage or internal resistance somehow. I used to repair portable PA systems (which contained 2 - 12v SLA batteries in series) and I developed my own tests for the batteries.

Parts - 1 car headlight, 1 SLA battery charger with status LED and voltmeter

First I would remove both batteries from the PA and fully charge them using the above charger.
Then I would load them one at a time with the car headlight while taking voltage readings at timed intervals. Soon sorted out a dud battery.
Of course only one was usually faulty out of the series pair but I would replace both anyway.

You do get clues to a batteries charge holding capabilitiy too (as per cell phone) when the charge time seems shorter than normal.
I learn't a lot about batteries while building and testing my electric car
eg Lead acid batteries should only be discharged to 50% Lithium to 80% (otherwise you kill them)

Sorry to drift a little there but although batteries are simple beasts they're not always easy to test.

Ross

rosnic0

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#1211193 9-Jan-2015 15:07

Sorry I see I didn't complete my answer to your last question. If the battery fails the test yes it is time to replace it.

Ross

timmmay

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#1211233 9-Jan-2015 15:58

Thanks Ross, I may just do something like that.

Jase2985

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#1211256 9-Jan-2015 16:14

just turn the mains off, measure the voltage, then come back in 30 mins and see how much its dropped.

once the battery gets down below about 11.8v stop measuring. if you know what the wattage of the alarm is you should be able to work out the currant draw and how long the battery should last with that load.

we have 24V batteries at work and just wack a 30A load on them for 3 hours to see how they go. They drop to about 23.6v from 25.5v in that time but take the load off and they spring back to 25 odd volts.

we also do the same with UPS units, turn the power off and put a known load on them and see how long they last.

timmmay

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#1730119 4-Mar-2017 21:36

I replaced the 7AH battery in my alarm today. It'd been up there for 5 years, which is the expected lifetime. It's probably never been used for longer than 12h at a time, it's never even been partly cycled.

I wondered what the capacity was after all that time. I put a 400ma load on it and measured the voltage drop over time. It dropped from 12.83V to 12.20V after 7h50m, which is 100% to 60% according to this chart. 400ma * 8h = 3.2AH, which according to possibly poor maths suggests current capacity is 5.3AH.

According to battery university "The optimum operating temperature for the lead-acid battery is 25*C (77*F). Elevated temperature reduces longevity. As a guideline, every 8°C (15°F) rise in temperature cuts the battery life in half." Up in the roof it goes down to probably not far off freezing in winter, and probably up to over 40 degrees in summer. Well, in a good summer.

So the battery has performed better than expected. Alarm batteries can probably be replaced on a 7-10 year schedule, depending on your desired runtime.

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mattwnz

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#1730122 4-Mar-2017 21:44

Probably a good reason not to install the alarm in the roof space and instead install the box in a cupboard where the temperature shouldn't get too high or low. The battery in mine latest about 8 years and when it needed replacing an indicator light on the panel showed this. I just got a 30 dollar one and it has been fine for several years. The alarm box has a trigger switch where the alarm will activate so you have to pull the contract of the battery fast to disable the alarm.

timmmay

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#1730206 5-Mar-2017 07:08

mattwnz: Probably a good reason not to install the alarm in the roof space and instead install the box in a cupboard where the temperature shouldn't get too high or low. The battery in mine latest about 8 years and when it needed replacing an indicator light on the panel showed this. I just got a 30 dollar one and it has been fine for several years. The alarm box has a trigger switch where the alarm will activate so you have to pull the contract of the battery fast to disable the alarm.

You should probably read the conclusion / answer rather than the question I asked months ago. TLDR: batteries last a long time in a roof.

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