Smoke Alarms - why have they moved to inbuilt fixed cells?

Kainz · 17 Apr 2019 at 16:08

Hey all,

One of our upstairs landing FireAngel ST-622's started beeping away earlier and I recall being displeased with the thing when we had it fitted a year ago - it was a free service from our local fire services. I am not a fan of these alarms with 'non user replaceable 10yr' batteries or the company tbh as they have a history of bad practice. Damn things never even last beyond a year in my experience.

I've been wondering why there was a shift from standard PP3 9v Battery powered alarms to ones that contain fixed batteries? Thanks to this failed battery I now have to lob a hunk of plastic in the bin when I could have easily changed the battery, if it was designed so. I hate wasting electronics goods.

I found some old school alarms on amazon https://smile.amazon.co.uk/Ei-Electronics-Smoke-Button-Batteries/dp/B00CDL8Z9W but aren't sure how these compare to modern ones that contain optical sensors. I only want to spend about £20 tops for 1-2 alarms and certainly not £40+.

DXP55 · 17 Apr 2019 at 17:05

Because the scrotes in social housing take them out to use in electronic goods.

a1ex2001 · 17 Apr 2019 at 17:29

Get mains operated ones with battery back up!

Kainz · 17 Apr 2019 at 17:51

a1ex2001 said:
Get mains operated ones with battery back up!

Unfortunately mains is a bit of an issue due to the spot where I want to site it.

eddiemcgarrigle · 18 Apr 2019 at 08:43

After every house fire it was quite common to find a smoke alarm stuffed in a kitchen drawer with it's battery removed. Hence the reason for fixed batteries.

dodg3rman · 18 Apr 2019 at 22:07

Perhaps you should have put your own up in the first place instead of getting the 'freebie' from the Fire Service. They probably bunged a shed load of glue on it and it took half your ceiling down when you removed it too.

Kainz · 18 Apr 2019 at 22:48

dodg3rman said:
Perhaps you should have put your own up in the first place instead of getting the 'freebie' from the Fire Service. They probably bunged a shed load of glue on it and it took half your ceiling down when you removed it too.

Given that smoke alarms have been a thing for donkeys years it is fairly obvious that we had them previously. The local fire services and FireAngel had a contract out to freely distribute x amount of units to households a good 7yrs ago, which the fire services would then come and fit for free. If the units expired then they would be freely replaced. The promotion has since ended and most of my road ended up ditching theirs.

Not a sure wtf you’re on about glue. Most people use things called screws and a mounting plate...

jellybeard999 · 19 Apr 2019 at 06:10

AFAIK smoke alarms detect using a chemical reaction, and the bit in the smoke alarm deteriorates over time. Maybe the idea is that people are forced to buy new?

Kainz · 19 Apr 2019 at 07:06

jellybeard999 said:
AFAIK smoke alarms detect using a chemical reaction, and the bit in the smoke alarm deteriorates over time. Maybe the idea is that people are forced to buy new?

Older alarms use an ionisation chamber to detect smoke and their reaction time is a bit slower. This also contains a small radioactive source. It does take a long time for an older alarm to deteriorate though so I think the reason for fixed batteries was as mentioned, because folks kept taking them out or wwrre) were slow to replace the batteries.

Modern smoke alarms that have the inbuilt batteries (never seem to last as long) have a photoelectric cell, which detects smoke faster and afaik doesn't go off when the toaster is on. The latter I find very wasteful though - I don't like the idea lobbing it in the bin and having to buy new as it is wasteful.