Lead acid batt. in home alarm system

[Tam Nguyen]

All,
The lead acid battery in my home alarm system is depleted and need
replacement. I have a question and hopefully someone expert enough can
answer this. Is there a good reason that I should not replace the battery
with an equivalent wall powered ac/dc to power the alarm circuit? Is the
battery there for the purpose of safety, security, or just convienience?

If it all posible, I want to have a wall powered ac/dc (with equal or higher
in current comsumtion) replace the battery so that I dont have to replace it
every few years.

Thanks in advance,

Tam N.

 

[Don Bruder]

All,
The lead acid battery in my home alarm system is depleted and need
replacement. I have a question and hopefully someone expert enough can
answer this. Is there a good reason that I should not replace the battery
with an equivalent wall powered ac/dc to power the alarm circuit? Is the
battery there for the purpose of safety, security, or just convienience?

If it all posible, I want to have a wall powered ac/dc (with equal or higher
in current comsumtion) replace the battery so that I dont have to replace it
every few years.

Well, there's a good logical reason not to do this...

What happens when the power to the house is cut - For *ANY* reason,
whether sinister, honest, deliberate, accidental, or otherwise? The
"Why?" of the power loss is completely irrelevant. The only thing that
counts is the "It's gone" part.

How well do you think the alarm system is going to work in that
situation once you've converted it to run off the power line, instead of
the battery?

Now think about how well the alarm works when the power goes out, but
the alarm is powered by a battery that's kept on constant standby charge
as long as there's power on the mains.

World of difference, huh?

In a nutshell, if you don't care that the alarm ceases to function if
the power goes out for some reason, then sure - You can do exactly what
you're talking about, with no problem whatsoever. If it's important to
you that the alarm continue to function even if the power is cut, (For
instance, if it has a fire alarm subsystem) then the ONLY way you're
going to get that to happen is replacing the battery as specified.

 

[Ken Weitzel]

All,
The lead acid battery in my home alarm system is depleted and need
replacement. I have a question and hopefully someone expert enough can
answer this. Is there a good reason that I should not replace the battery
with an equivalent wall powered ac/dc to power the alarm circuit? Is the
battery there for the purpose of safety, security, or just convienience?

If it all posible, I want to have a wall powered ac/dc (with equal or higher
in current comsumtion) replace the battery so that I dont have to replace it
every few years.

Thanks in advance,

Tam N.

It's there so your alarm will still be up during power
failures... either "real" or bad guy created.

And depending on the alarm and monitoring type, the
absense of the battery may report a fault.

And if you get a reduced rate on your insurance
for having an alarm, you might find that you've
either cheated on your policy so that it's
no longer in force if and when you need it, or
that your premium goes up.

I'd suggest sticking with the battery - they're
worth far less than the contents of your home.

Take care.

Ken

 

[Allodoxaphobia]

All,
The lead acid battery in my home alarm system is depleted and need
replacement. I have a question and hopefully someone expert enough can
answer this. Is there a good reason that I should not replace the battery
with an equivalent wall powered ac/dc to power the alarm circuit? Is the
battery there for the purpose of safety, security, or just convienience?

If it all posible, I want to have a wall powered ac/dc (with equal or higher
in current comsumtion) replace the battery so that I dont have to replace it
every few years.

Thanks in advance,

I'm pretty certain that your home alarm system does *not* run off
the battery. But, rather, the home alarm system keeps the battery
"float charged" so that when the bad guys cut the power to your house
and attempt to break in, the battery is Full Well Ready And Able
to ring The Big Bell, dial the police, and trigger The Barking Dog
speaker.

Jonesy

 

[Paddy Bag]

All,
The lead acid battery in my home alarm system is depleted and need
replacement. I have a question and hopefully someone expert enough can
answer this. Is there a good reason that I should not replace the battery
with an equivalent wall powered ac/dc to power the alarm circuit? Is the
battery there for the purpose of safety, security, or just convienience?

If it all posible, I want to have a wall powered ac/dc (with equal or higher
in current comsumtion) replace the battery so that I dont have to replace it
every few years.

Thanks in advance,

Tam N.

They should last several years and are not expensive, like mentioned they
are a backup in event of power failure, also another bad point for you to
consider, as most sounder boxes also have a battery backup they would in
the event of a power cut or even pulling the fuse on the alarm circut be
triggered, how could they tell it was you pulling the fuse or a theif
cutting the wires?

 

[Tam Nguyen]

See the replied/question below:

Well, there's a good logical reason not to do this...

What happens when the power to the house is cut - For *ANY* reason,
whether sinister, honest, deliberate, accidental, or otherwise? The
"Why?" of the power loss is completely irrelevant. The only thing that
counts is the "It's gone" part.

How well do you think the alarm system is going to work in that
situation once you've converted it to run off the power line, instead of
the battery?

TAM: is the battery also powered the horn (thought it only power the
electronic circuit)? I do believe that, in normal circumstances, the horn
is powered by the wall powered transformer. If the power line goes out,
would the batt is used to sound the horn?

Now think about how well the alarm works when the power goes out, but
the alarm is powered by a battery that's kept on constant standby charge
as long as there's power on the mains.

TAM: same as the question above!

World of difference, huh?

In a nutshell, if you don't care that the alarm ceases to function if
the power goes out for some reason, then sure - You can do exactly what
you're talking about, with no problem whatsoever. If it's important to
you that the alarm continue to function even if the power is cut, (For
instance, if it has a fire alarm subsystem) then the ONLY way you're
going to get that to happen is replacing the battery as specified.

--
Don Bruder - [email protected] - New Email policy in effect as of Feb. 21, 2004.
I respond to Email as quick as humanly possible. If you Email me and get no
response, see <http://www.sonic.net/~dakidd/main/contact.html> Short
form: I'm trashing EVERYTHING that doesn't contain a password in the

subject.

 

[Paddy Bag]

if there is a power cut the battery usually powers the entire system, PIR's
/ sounders/ contacts/ for how long depends on the size of the battery. The
designers of these things really think it out, so like said before the box
usually has a battery as a third line of defence and even may be triggered
for a few minutes even by a regular engineer taking the cover off

 

[Tam Nguyen]

I am not sure if the batt. also powers the horn when the line goes out,
because there is a transformer in the wall socket that I think it is there
to run the horn. So in the power line goes out scenario (regardless of
circumstances), would the horn draws juice from the batt to blast?

Tam N.

 

[Tam Nguyen]

Sound like the best way is to stick with the original design. I'll get the
bettery replacement.

Thanks all for your opinions and helps.

Tam N.

 

[Ken Weitzel]

I am not sure if the batt. also powers the horn when the line goes out,
because there is a transformer in the wall socket that I think it is there
to run the horn. So in the power line goes out scenario (regardless of
circumstances), would the horn draws juice from the batt to blast?

There are so many types of alarms that it's impossible
to do more than guess...

If you're adamant that you want to do away with the
battery; then what you might consider is talking
to your neighbors, and experimenting with it - at a
reasonable time. Not too early; not too late; not
the middle of the afternoon when the little ones are
trying to have their naps...

I still urge you to use the battery, though.
The designers put it there for good reasons.

Take care.

Ken

 

[Don Bruder]

See the replied/question below:



TAM: is the battery also powered the horn (thought it only power the
electronic circuit)?

Almost certainly yes. At least in every alarm system I've ever had any
dealings with.

I do believe that, in normal circumstances, the horn
is powered by the wall powered transformer.

Key words: "Under normal circumstances". The battery is there for the
times when there isn't any power to the building. As long as there's
power to the house, the entire alarm system is running from the
transformer. If there's no power to the house, the whole system switches
over to the battery in order to operate.

If the power line goes out,
would the batt is used to sound the horn?

That would be the way to run the thing. Otherwise, your nice, fancy,
expensive alarm system could be "shut off" by the bad guys simply
cutting your power at the pole.

TAM: same as the question above!

Same answer.

 

[gothika]

Almost certainly yes. At least in every alarm system I've ever had any
dealings with.

Yes the horn does run off the juice provided by the incoming hot power
but must have the backup battery for when the intruder cuts your
mains.
Also every unit I've ever installed won't give you a green on self
check during start up if it doesn't detect a good battery.(The
startup/selfcheck mode checks the battery for dwell and functionality
and won't give green if there's no battery or if the battery is dead.)

Key words: "Under normal circumstances". The battery is there for the
times when there isn't any power to the building. As long as there's
power to the house, the entire alarm system is running from the
transformer. If there's no power to the house, the whole system switches
over to the battery in order to operate.



That would be the way to run the thing. Otherwise, your nice, fancy,
expensive alarm system could be "shut off" by the bad guys simply
cutting your power at the pole.


Same answer.

The simple solution is to get a bigger capacity battery and perhaps
one with longer life.
I've used motorcycle batteries for some of my customers. They're
vented wet cells that have much longer life than the closed drycell
lead acids.
there are also other types of batteries.
gel cells, others with different chemical makeups that offer longer
life.

 

[Dave Baker]

They should last several years and are not expensive, like mentioned they
are a backup in event of power failure

Anyone have any specs on how long these "rechargeable batter nonspillable"
should last in alarm (or similar) systems?

I have one for my electric gate & I notice that even though the whole system
is only 1 year old, it didn't work when we had a power failure last year.

Also, anyone know the correct voltage that these batteries should be floated
at? I used a multimeter on mine, and it is sitting at 14.3V DC. Will this
harm the battery?

Dave

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All replies to the group please.

 

[gothika]

Anyone have any specs on how long these "rechargeable batter nonspillable"
should last in alarm (or similar) systems?

I have one for my electric gate & I notice that even though the whole system
is only 1 year old, it didn't work when we had a power failure last year.

Also, anyone know the correct voltage that these batteries should be floated
at? I used a multimeter on mine, and it is sitting at 14.3V DC. Will this
harm the battery?

Dave

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All replies to the group please.

You didn't mention the Ah rating of your batt.(since it's for a gate
I'm guessing that it's at least 9Ahs.)
14.3 is just a static reading and about right. Test it under load and
take a current reading. You'll find that on a good battery it'll drop
to 11.9 to 12.4/5 on average on a load.
I've seen some replace sealed lead acids with sturdier types of
batteries. depending on how strong the charging circuit is and it's
output rating you can go up to a car battery.
I've used large motorcycle batteries as replacements for SLA's for
things like garage door openers and warehouse door openers.
Usually 14 to 20 AH in size.
Good thing is you can tag on a small 1amp trickle charger if the
control units charger isn't up to it.
Also you can remove it at intervals to give it a 4-8 amp quick charge
to burn off any sulfation, thereby prolonging battery life.
Since it's a wet cell you can check specific gravity as well, letting
you know when it's time to change the acid or swap the battery.
Having a transparent case you can also inspect for plate erosion.
I get as much as 8 years off wet cells vs. the 2-3 for SLA.

 

[Dave Baker]

You didn't mention the Ah rating of your batt.(since it's for a gate
I'm guessing that it's at least 9Ahs.)

It's only a 7 amp-hour

I have to replace it anyway by the looks of it so I'll see if I can get
something bigger, and do some tests once I install it.

Thanks,

Dave

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[Mike Berger]

Most horns and annunciators draw more current than the transformer
is designed to provide, and rely on the battery.