Why do e.g. smoke detectors need specific battery models?

[f95toli]

I have once again come across a smoke detector which requires not only a specific type of battery (9V alkaline) but also a specific model (in this case Duracell MN1604) to be used.
I had a similar problem with a CO detector about a year ago (which came with a list of about 10 models that should work; must of which were no longer available) and I then tried some "unauthorized" batteries just to discover that the detector simply did not work with the "wrong" model; the "battery low" indicator (and beep) would turn on if the wrong model was used.
This time I am just going to order a new battery online (MN1604 is not available in the shops near where I live)

I presume that the detectors are designed so that they only work with a very specific EMF and/or internal resistance(?) since this (presumably) the only way to tell the difference between different 9V batteries, but does anyone know why this is the case?
Most well-designed electronic devices will work wide a fairly wide range of EMF and this is even true for most smoke detectors.

My theory is that it is the battery monitoring part of the circuit (the part that makes the detector beep when the battery runs low) that requires a very specif battery model to work; but that is just a guess.
Does anyone know for sure?

 

[anorlunda]

I think the dominant reason is battery leakage. The chemistry of all alkaline batteries are alike, but the quality varies. Inexpensive batteries might leak, destroying the detector and thwarting the function. Also think of the operating temperature extremes, -50C to +60C is conceivable.

I'm sure there are also marketing and contracts playing a role. The detector manufacturer might make a deal with a specific battery company to say that only their brand has been certified to meet the required quality standards. Of course there are ANSI and ISO standards, but there are also product placement financial influences.

 

[jim hardy]

Here's the datasheet for that battery. It is indeed 'plain vanilla' , an unremarkable but pretty good battery.

https://d2ei442zrkqy2u.cloudfront.net/wp-content/uploads/2016/03/MN1604_US_CT1.pdf

but there are also product placement financial influences.

Yes, in the music industry it's called "Payola" .

 

[CWatters]

I had a similar problem with a CO detector about a year ago (which came with a list of about 10 models that should work; must of which were no longer available) and I then tried some "unauthorized" batteries just to discover that the detector simply did not work with the "wrong" model; the "battery low" indicator (and beep) would turn on if the wrong model was used.

Very surprised at this. I think most PP3 9V Alkaline cells should work.

Were the "unauthorised" batteries zinc carbon rather than alkaline?
Were they rechargeable? The nominal voltage for a Duracell MN1604 is 9V but it's only 7.2-8.4 for rechargeable "9V" PP3 batteries.

https://en.wikipedia.org/wiki/Nine-volt_battery

 

[krater]

I do believe that like many other things that don't appear to make any sense at first glance, it is a listing/insurance issue. The detector was probably tested and listed by some third party, with a particular battery in it. Ergo, the only battery they can guarantee performance with is the one they used for the test.

 

[berkeman]

I have once again come across a smoke detector which requires not only a specific type of battery (9V alkaline) but also a specific model (in this case Duracell MN1604) to be used.
I had a similar problem with a CO detector about a year ago (which came with a list of about 10 models that should work; must of which were no longer available)

I know that for my AED (Automated Electronic Defibrillator -- a portable medical device used by EMTs and Paramedics), they specify only 3 brads of allowed replacement battery. Apparently the reason is that lawsuits had resulted from use of some other brands of batteries that could not provide the peak charging current needed to charge the output defibrillation stage in the required time. Perhaps with the CO/smoke detector qualification and use, there was some legal issue arising from some failed detectors that were traced back to inferior battery quality of some manufacturers.

and I then tried some "unauthorized" batteries just to discover that the detector simply did not work with the "wrong" model; the "battery low" indicator (and beep) would turn on if the wrong model was used.

That is interesting and surprising. I wonder how it detected a problem. Maybe it does some sort of output impedance test on the battery at initial power-up and periodically after that, and can tell something about some quality of the battery that is important for the long-life that is needed in the CO monitor application...?

 

[dlgoff]

That is interesting and surprising. I wonder how it detected a problem. Maybe it does some sort of output impedance test on the battery at initial power-up and periodically after that, and can tell something about some quality of the battery that is important for the long-life that is needed in the CO monitor application...?

That was my first thought. How else could "the problem" be detected?

 

[CWatters]

In my experience smoke alarms usually start chirping to indicate low voltage at 4am on a winter's night when the temperature is at its lowest. I suspect they just use cell voltage. The discharge curve is very flat making the state of charge detector sensitive to cell chemistry. Eg you must use alkaline cells.

 

[NascentOxygen]

I presume that the detectors are designed so that they only work with a very specific EMF and/or internal resistance(?) since this (presumably) the only way to tell the difference

You might be able to trick it into thinking you have a battery of much better manufacture than it really is by connecting a couple of polyester capacitors across its terminals. The detector's periodic gulp of test current may not sense much voltage drop with this. This is to investigate only, not leave as a permanent arrangement.

 

[anorlunda]

They put RFID chips in ink cartridges, any chance that they have them in batteries also? The cost is now as low as $0.01

Supermarkets hope to have an RFID chip on every item in the store, so that they can scan your whole shopping basket without removing he items.

 

[BillTre]

HP has been https://www.geek.com/tech/hp-screws-scores-of-customers-with-ink-cartridge-timebomb-1671409/ that result in third party printer cartridges being rejected.

 

[jim hardy]

HP has been https://www.geek.com/tech/hp-screws-scores-of-customers-with-ink-cartridge-timebomb-1671409/ that result in third party printer cartridges being rejected.

That's marketing for you. Second oldest profession.

 

[eq1]

That is interesting and surprising. I wonder how it detected a problem.

I was thinking the exact same thing as I can't imaging them adding extra cost to the BOM for that. My guess is the speaker requires some big cap in the alarm and not all knock off batteries can power the in-rush event hitting some kind of under voltage lockout.

 

[Tom.G]

...hitting some kind of under voltage lockout.

While in standby, the low-supply detection circuitry conducts periodic checks
using a pulsed load current from the LED pin. The trip point is set using two external
resistors. The supply for the MC145010 can be a 9 V battery.

Above from datasheet for MC145010 available at https://www.nxp.com/docs/en/data-sheet/MC145010.pdf

 

[NTL2009]

Very surprised at this. I think most PP3 9V Alkaline cells should work.

Were the "unauthorised" batteries zinc carbon rather than alkaline?
Were they rechargeable? The nominal voltage for a Duracell MN1604 is 9V but it's only 7.2-8.4 for rechargeable "9V" PP3 batteries.

https://en.wikipedia.org/wiki/Nine-volt_battery

Agreed, and I'd really like to hear from the OP @f95toli .

I fully suspect that any batteries that failed to work were of a different chemistry, or not fully charged, rather than simply a different brand. The smoke detector manufacturer is either covering themselves by stating specific brands they have tested, with maybe some additional assurance from the battery manufacturer with regards to their quality control, and/or it's just advertising.

I know people who have toured battery production sites, and they saw batteries come off the line, and those same batteries got the name brand labels and store brand labels.

 

[f95toli]

CO-FA-9B

Agreed, and I'd really like to hear from the OP @f95toli .

I fully suspect that any batteries that failed to work were of a different chemistry, or not fully charged, rather than simply a different brand. The smoke detector manufacturer is either covering themselves by stating specific brands they have tested, with maybe some additional assurance from the battery manufacturer with regards to their quality control, and/or it's just advertising.

I know people who have toured battery production sites, and they saw batteries come off the line, and those same batteries got the name brand labels and store brand labels.

Sorry for not being more active in the thread. I was trying to find the manual for the CO detector I mentioned above which had a long list of batteries.
Unfortunately I can't find it. The model was First Alert CC410 but it is an old model and I can't find the manual online.
Interestingly, the new CO detector we bought a few weeks ago does NOT specify a specific model it just says "Recommended Batteries: Size AA Alkaline - Duracell LR6, Energizer LR6, Gold Peak 15A" even though it is from the same manufacturer (CO-FA-9B). (the CO detector used AA batteries)

I can't remember which batteries I tried back then; presumably some other alkaline battery, most likely Duracell batteries (but the wrong model) since this is the brand sold by most stores near us.

Note also that the old CO detector (as well as our smoke detector) does not only specify a brand, but even a model meaning it is unlikely to be a quality issue. The label on the smoke detector says "use only 9 volt alkaline battery, Duracell MN1604; Energizer 9V. Other batteries can cause problems.". It is somewhat interesting that it specifies the model for the Duracell battery (which is no longer commonly available) but not for the Energizer.

If it was any other type of device I would just use whatever good quality battery I had at hand; but after my experience with the CO detector (which as I mentioned above did not work when I tried the wrong type of battery)I will stick the the recommended model.

 

[NTL2009]

CO-FA-9BSorry for not being more active in the thread. I was trying to find the manual for the CO detector I mentioned above which had a long list of batteries.
Unfortunately I can't find it. The model was First Alert CC410 but it is an old model and I can't find the manual online.
Interestingly, the new CO detector we bought a few weeks ago does NOT specify a specific model it just says "Recommended Batteries: Size AA Alkaline - Duracell LR6, Energizer LR6, Gold Peak 15A" even though it is from the same manufacturer (CO-FA-9B). (the CO detector used AA batteries)

I can't remember which batteries I tried back then; presumably some other alkaline battery, most likely Duracell batteries (but the wrong model) since this is the brand sold by most stores near us.

Note also that the old CO detector (as well as our smoke detector) does not only specify a brand, but even a model meaning it is unlikely to be a quality issue. The label on the smoke detector says "use only 9 volt alkaline battery, Duracell MN1604; Energizer 9V. Other batteries can cause problems.". It is somewhat interesting that it specifies the model for the Duracell battery (which is no longer commonly available) but not for the Energizer.

If it was any other type of device I would just use whatever good quality battery I had at hand; but after my experience with the CO detector (which as I mentioned above did not work when I tried the wrong type of battery)I will stick the the recommended model.

Thanks for the response. I'm still going to go with the assumption that the specific reference to a model # is just a matter of the model # of that brand at the time that they tested so recommended that known entity, and/or were paid to promote it. I don't think the exlusion of other brands/model #'s means much at all. Just looking at specs of different 9V batteries at the DuraCell site:

https://www.duracell.com/en-ca/techlibrary/product-technical-data-sheets?region=262&type=303

Yes, there are differences, but they seem slight, and probably irrelevant to a smoke detector. I see Internal Resistance of ~ 3 Ω on one model and 1.7 Ω on two of them. Significant, but I doubt it would make much difference at the currents these use.And they'd need to draw some fairly large current to test that delta and use some fairly precise voltmeter - I just can't see the point.

the charts show a service life of ~ 1 hour @ 250 mA, I can't imagine even the intermittent siren would draw more than that, they would want that siren to operate for maybe an hour even near the end of life of the battery. And that I*R delta would only be 0.325 V @ 250 mA, so really not a big deal.

 

[eq1]

While in standby, the low-supply detection circuitry conducts periodic checks
using a pulsed load current from the LED pin.

That's clever as the LED needs to be pulsed with somewhat strong current anyway. I should've know there was some magic IC that just "did" everything. :) Thanks for forwarding it.

 

[Blank_Stare]

That's marketing for you. Second oldest profession.

It may be the second oldest profession, or not...
Think about it - someone had to market the individual engaged in what is commonly referred to the oldest profession...
Even if it was just rouge and a wink...



My opinion? There's a reason that the folks in those two professions share so many personality traits!

Have fun!

 

[unix101os]

My intuition says that since a smoke detector/fire alarm is something that lives depend on then manufactures would heavily test their equipment and to validate the integrity of the product they have to be used under circumstances which most closely match testing criteria. This also frees the manufacture of any liability or risk untested batteries could cause.

 

[sophiecentaur]

When you climb aboard an aeroplane, you feel relatively safe because pretty much every aspect of its construction is specified very tightly. If some batteries here and a number of O rings there happened to be not quite what was specified, would you feel just as safe? We don't leave it to the whim of every service engineer to judge things right.
A smoke detector is along the same lines as an aeroplane. It only needs to fail once to spoil your day (or night). Also, not everyone is as well informed as erudite members of PF.