PSA: Don't buy smoke alarms with 10 year lithium batteries. (First Alert / Fireangel ST-620)

A quick video of something that has happened with my smoke alarm and I'm not alone!

[@MrDubje]

I bought this smoke alarm in February 2017, and it has reached a point where the intermittent chirping has become such annoyance that I took it down today.

[@Emyii90]

After 4 years, I've just had to contact them for an replacement

[@henryrussell2404]

I have had four of these damn devices fail within 4 years of purchase. In all cases I have dismantled to find the batteries still showing over 3 volts.I believe the problem is that the diodes may get dirty in some way and thus trigger the alarm to chirp.it does say in the instructions to regularly vacuum the alarm but this would be unlikely to remove dust or film from the ir diodes. I conclude that the basic operating principle of the device is not workable as it cannot be properly maintained.

[@zx8401ztv]

That's just mad, now the question is were the cells faulty or fake or did the alarm start to consume more and more power as the years ticked by. The ones in my house are rechargable battery types and they are powered from the mains supply. The best form of fire protection is Don't leave things unattended. When i go to bed, there is only the simple fridge powered, a tiny risk. You would be shocked by the amount of electronics and power supplys people have sitting on the carpet behind there computer desk running for years. Some are old supplys from devices they do not have any more, just sitting there powered for no reason.

[@MrDubje]

Probably faulty cell or badly designed circuit. I didn't test it too much, that's for sure (who does that anyways?). So, it can't have been due to testing and draining the battery. It is still fine during the day, but when the heating comes on or the recently installed airconditioning on (in heat mode) is running it throws a fit. It's intermittent, too. For an empty battery, it is supposed to chirp every 45 seconds, and while it does that sometimes, it sometimes leaves a gap between chirps of minutes, making me less convinced that it is actually the battery. At first I thought it was dust or something causing it, since the heat mode of the air con does blow slightly in its direction, But even when the air con isn't on, but the regular heating is, it yesterday-evening decided to chirp again until I took it down. I suspect the temperature variations have an effect on the internal circuit, but if that's the case, I don't trust it!

[@zx8401ztv]

It almost sounds like it has a loose/crappy battery connection that changes resistance with air dampness/dryness. It could be female as they get picky with heat he he :-D

[@whitefields5595]

I have the same fault on 6 units that failed after 5 years. I opened them up and cut out the old battery that was still reading 3.05 Volts. I reconnected to a bench power supply and took it up to 3.2 V. At no point did the device start working. This fault was more serious than just a flat battery.

[@mistermartin82]

In Scotland from next year its 10 year sealed lithium or mains smoke alarms only

[@ChrisG3253032]

We've had this same alarm, the "fire-angel" st-620 model throughout our house, been trouble free for around 6 years but my bedroom one is now chirping. Time for replacement I think.

[@dazednconfused31337]

I found a relative's alarm wouldn't sound from the test button (even in the bracket). The metal tab inside was too short to be lifted by the bottom plastic prong - which enables the battery when installed. So I I bent the metal tab away to enable it forever, which worked - but it beeped & flashed non stop! So I wonder if it then shorted to the battery like mentioned earlier.

[@bobmcgrath1272]

Have two fireangels and last night they started chirping the low battery warning. Really quite annoyed as they’re only 3 years old. (Don’t think I’ve a receipt)

[@msbo5171]

Have a Fire Angel one - same thing - was chirping after less than 3 years. Sent a photo of the model number/back info to them, was automatically sent a new one. That replaced the upstairs one, but the downstairs alarm is chirping now after 4 years and I can't remove it from the ceiling - does not untwist, super annoying. Should last longer and be able to easily replace.

[@brianeasson889]

If you have found that one of your smoke alarms does not untwist, you may have inadvertently knocked out all the locking tabs when installing and the alarm which will lock it onto the base plate. Simple solution, if you look in at the side of the alarm, roughly where the tear shaped sensor is located, there's a small tab which you push up slightly, rotate the alarm and it should come off.

[@language_and_society]

Thanks for this video. Very useful. We had the same fire alarm and same problem

[@AkaHexx]

Thanks for the help about to fall asleep on my couch and the battery acted up and it was ringing and I had to take it out

[@abualis1178]

I had the same issue with 2 of these types within a year they are DONE.!

[@TheAkashicTraveller]

With the ST-750 if the sounder and postitive battery terminal short together it starts screeching. Guess where they put the battery and souunder?

[@MrDubje]

I'm not familiar with that model, but by the way you wrote that comment I guess they placed them ridiculously close next to each-other or something?

[@TheAkashicTraveller]

There's about a milimeter between them. Took a shower and it started. First day it stopped after 10 minuets second I came back from work to it still going.

[@MrDubje]

@@TheAkashicTraveller Yup, shitty design at its finest! Thanks for commenting!

[@abya2630]

Mine only lasted 5 years. This is not a good brand and its expensive to replace. Customer service was not very helpful.

[@adlerweb]

Depending on your building type and regulations models with changeable batteries or rechargeable ones are sadly not certified :(

[@MrDubje]

I've never heard of that. This house is from 1974 or so, and as far as I'm aware in the Netherlands the electrical installation has to be up to code for the year the house was built. New houses have mains powered smoke alarms in them, so it might apply to those. I would have to read up on it.

[@adlerweb]

@@MrDubje In Germany every inhabited building must be fitted with certified smoke alarms, usually at least bedrooms, stairwells and hallways. Replaceable battery smoke alarms are usually sold as compliant, however some codes demand a runtime of at least 36 month and the batteries included are usually not the quality up for that task. Electrical installations must also be updated to current standard if it is older than 40 years or as soon as changes (like adding a socket) are carried out. As usual we got loads of regulations telling you what is compliant (and also as usual if you read two of them you've got two mutually exclusive requirements). I've never seen 230V smoke alarms around here - usually there are bus powered sensors for central alarm system in commercial buildings (which can of course only be installed by certified companies) or lithium models for other houses. We're also required to replace all smoke detectors at least every 10 years to prevent "sensor degradation". IMO BS because the LEDs/diodes usually last way longer and even the cheapest ICs implement regular sensor self tests to detect and notify you if there are problems.

[@stinkycheese804]

@@adlerweb You don't know what you're talking about. First, one thing might be required in Germany but you stated initially as if this is some universal thing. Certainly any major brand is selling a certified detector for the region it's sold in. Second, no, LEDs easily have less than 10 years of life with that being 88K hrs. It's not the case here since these are only intermittently pulsed, but no, there is no such thing as a sensor self test that can differentiate between a low LED output or photodiode sensing, versus contamination or legitimate smoke condition it was meant to detect. They all have the same result in low sensing. There's the issue. Odds are that people experiencing the premature chirping are merely in dusty or otherwise contaminated environments where deposits form on the emitter or receiver. AC mains powered smoke detectors are not uncommon at all, in residential properties built after their advent so the wire was in place for them already, since it is far more of a hassle to wire that later, having to potentially go through many floor/ceiling joists to link them all together, when battery powered exist. Depends on the building design and whether you are locating them where most needed.

[@adlerweb]

​@@stinkycheese804 That's why I wrote "*Depending on your* building type and *regulations*" (as in your local regulations). I've never seen mains powered ones sold here (besides shady online shops), only battery or networked and centrally controlled fire alarm systems . Usually the ICs differentiate between gradually and rapidly decreasing return levels. If the senor level decreases over weeks you can usually guess it's not a fire but a bad sensor and/or dust.

[@lasersbee]

What Voltage are the Lithium batteries in the unit ?? Why not replace the battery... It did last 3 years. My detectors use rechargeable 9V NiHM batteries and last just over 1 year.

[@MrDubje]

It has a 3V lithium cell inside, and while you're correct about the regular battery replacement interval of one year and the fact that I can probably find something to replace it with, it's under the manufacturer's warranty and sold as a ten year unit. That's their selling point. I'm first going to see how this works out. If it doesn't, we'll take a look together by means of a video.

[@lasersbee]

@@MrDubje Yeah if still under warrant I'd take it back as well. Sounds like a plan...

[@whitefields5595]

I did just this and took them up to 3,2 Volts on a bench power supply. Still no joy. The fault is more than just a flat battery,. It could be the PIC microcontroller puts them into shutdown on low voltage from which they cannot be recovered?

[@defox_nz]

exact same problem i have!

[@lunepilot2874]

Fire Angel is utter rubbish I’ve had one of the carbon monoxide detectors battery died after 3 months use. Supposed to last 7 years.