Low battery indicator

Hi,

Last night, kept hearing a short little "tune" (1-2 seconds) throughout the night. Eventually convinced myself it was

*not* part of a bizarre dream sequence. Come morning, I actively sought it out.

This proved difficult as it would only occur every 4 or 5 minutes and was just a second or two in duration (so hard to localize).

Turned out to be a cell phone complaining of low battery (?) [I don't use a cell phone, so would never have considered this possibility].

Phone was "off" so obviously something is waking itself from deep sleep, periodically, to test the battery and then complain that it is low. (presumably, there is some value to this feature?)

Of course, we all know smoke/CO detectors like to chirp interminably as their batteries fail. Lacking any real smarts, it is understandable why a smoke detector will chirp *every* "minute" since it basically sits dormant most of the time and just wakes up to "sniff the air" (and the battery!) before going back to sleep.

But, what's the rationale in having a *smart* device (e.g., cell phone) take the same sort of uninspired approach? I.e., assuming there is some value in warning the user WHILE THE PHONE IS OFF that the battery needs a charge, why such a naive implementation? Wouldn;t it make more sense to backoff (exponentially?) with the notifications?

I assume if the user *used* the phone in this time, he would be more directly notified of the "low battery" status. So, why waste battery playing silly little songs every 5 minutes indefinitely?

And, how does this rationale apply to other "persistent" indicators? E.g., the "fasten seat belt", "door open", "headlights are still on", "you forgot your keys, dummy", etc.

Reply to
D Yuniskis
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I guess the value of the alarm is in letting the user know self discharge has flattened the battery and that it's time to charge it up so it will be usable when you need it.

It could be a lot more frustrating to find if the warning inteval was too long (speaking from the experience of having 4 battery powered smoke detectors @ home).

Reply to
kelly

Stanley tools makes a tool just for silencing cell-phone alarms.

Their part number is 57-550 - about $US 60

RK

Reply to
d_s_klein

No, the fixture used to test these would be more appropriate (hint: the test terminates when the *handle* -- typically hickory -- snaps!)

:>

Reply to
D Yuniskis

But there is no way to *acknowledge* these alarms OTHER THAN to recharge (in the case of the phone) or replace (in the case of the smoke detector) the battery. I.e., it is an incredibly naive "alert" in both the way it announces itself *and* the way it is acknowledged by the user.

E.g., the last time my AC/DC smoke detectors (both, simultaneously) started chirping, the only remedy I had was to *unplug* them! Mind you, they are operating on AC *despite* the fact that they have *detected* their backup batteries to be low. So, I have to opt to disable them completely until the stores open in the morning (and, hopefully *remember* to buy replacement batteries now that they have *no* possibility of reminding me!) or listen to them chirp through the night.

Reply to
D Yuniskis

Am 24.06.2010 17:46, schrieb D Yuniskis:

For the smoke alarm, that's the only sensible thing to do. A smoke detector without a sufficiently charged battery is, for all intents and purposes, nothing but an ugly, useless brick of plastic screwed to the ceiling.

It _cannot_ sanely stop trying to sound the alarm without a sufficiently charged battery in place.

It would be even more naive to assume that the person who acknowledged the alarm will _really_ remember to exchange the battery before it runs out completely, without an occasional reminder. It would be naive to even assume the person who acknowledged the alarm as much as _told_ the person in charge of exchanging the batteries about it.

For the smoke detector, I think you're wrong on both counts there. It cannot be announced any other way (because the device has no other signalling method that is likely to attract attention in time), and there _is_ no sane way for the user to acknowledge an out-of-power situation other than to supply power.

So, if you don't care about their backup battery serving any useful purpose --- why did you by devices with backup batteries in the first place?

Reply to
Hans-Bernhard Bröker

Am 23.06.2010 23:08, schrieb d_s_klein:

And sane cell-phones support a mode to silence them completely (including the battery-off alarm). For somewhat obvious reason, it's called "airplane mode".

Reply to
Hans-Bernhard Bröker

no it's not. airplane mode has to do with connecting to the cell phone network. It'll stop ringing, but it'll also stop all incoming and outgoing calls as well as any other cellular network access.

Reply to
AZ Nomad

I disagree. I would consider a smarter algorithm to begin periodic "alerts" before the battery is depleted. At some

*long* interval (15+ minutes... maybe even an hour!). This allows a user to act on the alarm before it becomes annoying.

As time progresses, the alerts can become more frequent.

Or, the device could allow you to silence the alerts for ~12 hours (by pressing the TEST button) for the first

48 hours (?). After that, it can become more insistent.

What happens if the battery dies while you are away for the weekend? Or, on a week long vacation? You come home and there is no annoying chirp -- nor are the detectors operating! Until your next monthly (manual) test, you are living without protection.

-----------------------------^^^^^^^^^^^^^^^^^^^^

A reminder every 60 seconds is not an "occasional reminder". It is an annoyance.

(imagine if your kids asked you when you're going to depart for the amusement park EVERY 60 SECONDS -- just an occasional reminder!)

The scheme I outlined is more fitting. When you first encounter such an alert, you *probably* aren't ready to "drop everything" to attend to it. If it came back and reminded you an hour later, you'd probably think, "Oh, yeah. I forgot, I was going to go out and buy some batteries for that thing!".

Eventually, a procrastinator encounters a more insistent alert. But, at least he is *ready* for it. He *knows* he has been previously warned and has been procrastinating (for whatever reason).

E.g., we have a little travel alarm clock that behaves in a similar fashion. The first time the alarm goes off, it is very unobtrusive. If you are lying in bed, awake, you will hear it and act accordingly (whatever that entails). After a while, it will gradually increase in volume -- become more insistent.

At any time, you can silence it with the "snooze" bar. This is only temporary as it will resume once the "snooze" interval has expired.

The smoke alarm (and cell phone, etc.) could behave similarly with the additional condition that they would disallow "snooze" after a certain point in the battery discharge cycle (note that this cn be controlled by monitoring battery voltage instead of some fixed timing algorithm)

AC powered detectors are mandated in the latest Code. Precisely because people would remove the batteries from chirping smoke detectors and *never* replace them (out of sound, out of mind?). Apparently, lots of fires (including fatalities) are found to have smoke detectors present but disabled -- hence the reason for the Code change.

Given that you have AC power available, a smoke detector

*could* implement the additional smarts outlined above. At least insofaras its on-line testing of the backup battery. While on battery, one *could* argue that the cost of those smarts (some ultralow power logic??) could impede the operation of the device. I contend that the cost of emitting a chirp probably exceeds the cost of a simple state machine to implement the above algorithm.

I believe smoke detectors behave the way they do because they don't have any sense of state/memory. I.e., they run a fixed cycle: sample environment, make decision, alarm if required, sample battery, alert if required, sleep (to conserve battery). Lather, rinse, repeat.

There is *no* reason why a cell phone is as stupid as it is! :-/

Reply to
D Yuniskis

Am 24.06.2010 18:33, schrieb AZ Nomad:

... which is exactly the state a phone _should_ be in if its owner's only reaction to the low-battery alarm is annoyance. Because that person obviously couldn't care less about whether their phone works or not, so for the sake of general energy economy and bandwidth conservation, their phone should be completely off. Arguably, there shouldn't be a battery in it in the first place. Or they shouldn't even have a cell phone.

Reply to
Hans-Bernhard Bröker

And that's what all battery-driven smoke alarms I've seen do. They start out at a most-of-24-hours interval (not exactly, to avoid beeping at exactly the same time when nobody's home every day).

If your combined-power devices behave differently, that's, basically, your problem. Buy more sensible ones next time round. ;-p

The ones I've seen started beeping way longer than one weekend before they're dead. They'll keep it up for weeks if you let them.

Security beats annoyance. It might even be said that security _has_ to be annoying to be worth a damn.

There is --- that reason just fails to apply to _your_ cell phone.

It all depends on how important it is to their respective owners that they'll be ready-to-go 24/7. You apparently want the smoke-alarms to be primed all the time, but couldn't care less about the phone. Fair enough. But the "typical" user of a cell phone envisioned by their producers may see that differently, and that's who they tune those things for.

One other reason cell phones alert more frequently and insistently is that their battery operation time is a whole lot shorter than that of a smoke detector --- by about two orders of magnitude. That also applies to the time between low-battery alarm and total depletion. That time can drop well below that of a good night's sleep, so phones have to alert more often to give people a chance to recharge in time.

They also display their charge state all the time, to give users a chance to avoid ever getting into low-battery alarm state. Even owners who very rarely actually use their cell phones (let's call them "what-if" users) usually get into the habit of checking the charge state roughly once a day, or charge every weekend.

Reply to
Hans-Bernhard Bröker

airplane mode probably won't disable such a low battery alarm

The only way to eliminate such an idiotic alarm is to pull the battery, or keep it charged. Or perhaps in a soundproof box.

Reply to
AZ Nomad

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