Alarm system backup battery problem

[Osem]

I've just discovered that our alarm system (Sterling 10 installed 5-6 years ago) has a problem. When the mains is turned off, the main alarm sounds even though the alarm system is 'unset'. What's more, the remote illuminated keypad goes dark/blank and no longer operates so I can't reset the system or stop the alarm until the power is back on when the unit operates normally again. In the past, during a power outage in its unset state, it would remain illuminated but sound a periodic beep every 10 seconds to alert us to a power supply fault. Since this no longer happens I'm assuming the internal 12v backup battery has failed. Presumably the external sounder is going off because has its own battery and is falsely detecting a tamper condition due to the lack of backup power from the main unit.

Anyway, I've had a look on the net and found a couple of posts on this subject which I'm not sure about so would like a bit of feedback from people I trust i.e. you lot! I'm hoping it'll be a straightforward job to replace the internal lead acid battery but am a little worried that if I go about this the wrong way I might wind up causing spurious set up/code problems which I can't sort out. Since I have to turn off the mains supply before I open up the control box the alarm is going to sound until I can get the power back on again so I'm wondering if there's a certain procedure I should follow (e.g. I know there's an engineering mode but I don't have the code for it) and if I remove and replace the battery with a new one am I likely to have any issues when powering the system back up? I guess I'm wondering if the unit might become 'confused' in some way because it's been subject to power interruption and tamper conditions at the same time. The last thing I want is to turn it all back on only to find can't stop the alarm going off...

One forum mentioned that the internal battery is this MM26D available from Maplin for £38:

http://www.maplin.co.uk/sealed-lead-...atteries-19363

But I've found what seems like a very similar battery for half that price from Screwfix here:

http://www.screwfix.com/p/sealed-lea...ails_container

Would this work? (obviously I'd check what the existing battery is before buying a replacement).

http://www.screwfix.com/p/sealed-lea...ails_container

Any help much appreciated as always.

[Uncle Peter]

Should be fine providing it has the same Ah rating as the existing one (should be printed on the side of the battery).. and it fits in the box of course

[Osem]

Thanks for that. Now just waiting for answers to my other questions...

when my alarm was installed I was given manuals to read and was given both operating and engineers codes lol

[iain_herts]

hi does this help

http://www.fire-alarm-specialists.co...ICON%26LCD.pdf

[Osem]

Originally Posted by iain_herts

hi does this help

http://www.fire-alarm-specialists.co...ICON%26LCD.pdf

Hi and thanks for that. I do have a manual but it doesn't explain about the procedure for battery replacement and the guy who installed the system emigrated a few years ago. It may well be that the procedure's simple and needs no codes to be input but forewarned is forearmed or so they say.

[AbyssUnderground]

12v 7.2Ah is a standard battery for alarm systems (the one you mention on your maplin link). These are often also sold as 7Ah or 7.5Ah, they're physically the same size. Try eBay too, they're often a bit cheaper. Providing the voltage is 12v, a smaller Ah battery will work but it just won't last as long when the power is off and of course it may not fit any slot that the battery is designed for if the size is different. Since it's not going to move I doubt it will be an issue.

[Osem]

Problem fixed - I hope...

It was a bit more complicated than I thought and I've posted the details here:

http://www.cableforum.co.uk/board/35646747-post76.html

Will report back tomorrow.

Thanks for your help - Abyss, Iain and Uncle Peter.

---------- Post added at 12:20 ---------- Previous post was at 12:16 ----------

Originally Posted by AbyssUnderground

12v 7.2Ah is a standard battery for alarm systems (the one you mention on your maplin link). These are often also sold as 7Ah or 7.5Ah, they're physically the same size. Try eBay too, they're often a bit cheaper. Providing the voltage is 12v, a smaller Ah battery will work but it just won't last as long when the power is off and of course it may not fit any slot that the battery is designed for if the size is different. Since it's not going to move I doubt it will be an issue.

TVM - Got the battery from Screwfix in the end. Toolstation had them at £15 but none in stock so popped across the road and got the more expensive one.

[Osem]

Just tested the system by disconnecting the mains supply and the new backup battery seems to be working.