Long-life smoke alarms versus lithium batteries

Forums › Home Workshop DIY › Long-life smoke alarms versus lithium batteries

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Hammerer

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#1262100 19-Mar-2015 08:22

NZSpides: Since no one has even mentioned it yet, I will.

If you have an alarm system (many people do have a security system) why not simply get smoke detectors added onto your alarm?

Yes, the point is worth making. I thought about mentioning it earlier as we have a photoelectric (smoke detector) sensor in our hallway connected to our monitored alarm system. We still have separate battery powered detectors in each bedroom because people like to close their doors at night.

GregV

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#1262110 19-Mar-2015 08:55

I replace the smoke alarm batteries every 6 months, and then chuck the old ones in the cupboard to use up in kids toys etc. Just recently painted the ceilings, so the old alarms got replaced as they were yellow.

jonathan18

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#1262139 19-Mar-2015 09:26

Hammerer:
NZSpides: Since no one has even mentioned it yet, I will.

If you have an alarm system (many people do have a security system) why not simply get smoke detectors added onto your alarm?

Yes, the point is worth making. I thought about mentioning it earlier as we have a photoelectric (smoke detector) sensor in our hallway connected to our monitored alarm system. We still have separate battery powered detectors in each bedroom because people like to close their doors at night.

We do have one hard-wired smoke alarm in the hallway that was there when we bought the house, but I hadn't thought whether that was connected to the alarm or not! The alarm looks fairly old, but I guess that's not proof either way. How would I test this - light a small fire in the hallway?!

If it is connected to the larm, then yep that's a sensible thing to explore. How do such alarms work in a power cut - just rely on the power from the alarm's battery?

Jase2985

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#1262193 19-Mar-2015 10:27

yes power from the alarms battery, should easily last 2 hours and most should last 6-8 hours, they dont draw much power/current.

easiest way to find out is burn some toast under it :) if the siren/screamer goes off then its connected.

MadEngineer

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#1263511 19-Mar-2015 16:08

Not mentioned because it's a no brainer :)

And yes, the amoke alarm should set off the alarm and it's worth testing this during both night and day modes.

You're not on Atlantis anymore, Duncan Idaho.

Niel

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#1263581 19-Mar-2015 17:25

If an alarm system does not have a tamper detection circuit (which is always active except for a few minutes when a service code is entered), then it is not worthy to be called an alarm system. So if it is worthy to be called an alarm system, then a hard wired smoke sensor can be wired into the tamper circuit (if there is no dedicated fire sensor circuit).

Alarm batteries should power the system for a number of days, else a thief can just cut the power and wait a few hours before breaking in...

You can never have enough Volvos!

lapimate

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#1263694 19-Mar-2015 21:14

timmmay: … I bought smoke alarms recommended by Consumer …

I find the problem with such NZ Consumer reviews is that they are a snapshot performance evaluation. Their tests do not represent longer-term performance. For example smoke alarms; dehumidifiers that have a good quiet dB rating initially but then deteriorate over quite a short time (bearings or whatever). With some items they do do surveys of user experience.

timmmay: … We don't put any smoke alarms near the kitchen …

In our kitchen and internal garage we have installed Cavius Heat Alarms 3002-007 (temperature sensor) to complement the smoke alarms in other parts of the house.

The blue-plastic-covered lithium ER 9V battery in our PE Orca OM588H-LL (“10-year”) registered a voltage into 22kOhm load of 10.91V. Various other brand lithium batteries showed 9.33V to 9.85V. Eclipse lithium is the one I use for replacement.

Over the years we have had several smoke alarms fail or give false alarms even with brand new batteries. Sometimes connected with low temperatures. No wonder people get fed-up with them and rip the batteries out; there must be a lot of money extracted from consumers for no long-term value. Personally for PE I now favour FireAngel Thermoptek 10 year ST-620 which are stated to combine PE with thermal enhancement. But PE & ionisation alarms do have different detection capabilities so we have both.

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jarledb

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#1264070 20-Mar-2015 14:27

One thing that can be good to know about when it comes to photo electric smoke detectors is that they are susceptible to false alarms when you get condensation of moisture in the air.

In the safety company I ran we would get a lot of calls from people having false alarms in the spring and fall, when temperatures would fluxuate between high daytime temperatures and low night time temperatures.

Especially when the temperatures drop from over +18 to lower than +15 this can occur. If you are unlucky enough for the moisture to turn into water inside of the light reflection chamber of the photo electric smoke detector, it will see it as smoke (the light will be reflected by the water), and you will get a false alarm.

So for photo electric smoke detectors you are usually best off making sure they are in room where the temperature don't fluxuate a lot (and don't go under +15 celcius).

Another thing that can set off false alarms are small insects (or pollen) getting into the chamber. Many newer smoke alarms will have filters to stop this around the detection chamber.

With ionisation alarms you can get false alarms from things like heavy wind, and they love telling you that you are making food - so no smoke alarms are perfect.

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