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Next Smoke Detector Millionaire or Not?

Discussion in 'General Electronics Discussion' started by Ampedup, Feb 15, 2020.

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  1. Ampedup


    Feb 15, 2020
    Are you familiar with the 9V battery that has a micro USB cable charger, like the one in the photo. So, maybe someone can explain to me why no one has come up with a way to trickle charge a 9V battery while in the smoke detector. I realize the purpose of the battery is to protect in the event the power goes out. But if the battery could be charged either continuously or periodically couldn’t the 9V battery that’s capable of 500 charges last a very long time? In case you’re wondering why I ask this, it’s because of a few reasons: 1) my vaulted ceilings are 25 feet high (almost have to rent scaffolding to replace the battery - ridiculous). 2) My home insurance company requires the batteries be replaced once a year whether it’s needed or not or I may be subject to non-compliance; therefore no coverage - again ridiculous!

    Ok, so I’ve learned that most USB ports output 500 milliamperes to a particular device. If that’s the case, if you install the 9V battery in the detector and plug the micro cable into the 9V battery port and cut off the USB connection exposing the wire and then it’s a matter of supplying 500 amps through the cable from the power source, right? Maybe there’s a problem with continuous charging causing the battery to over heat or explode? Can this be overcome with intermittent charging somehow? Or is this idea completely cost prohibitive?
    Please let me know if I’m missing something with this line of thought. Your feedback is welcome.

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    Last edited: Feb 15, 2020
  2. BobK


    Jan 5, 2010
    The ones with 10 year lithium batteries have made it less of a concern.

    I suspect that rechargeables are not seen is based on not being certified because the cannot meet reliability standards.

    davenn and bertus like this.
  3. Audioguru


    Sep 24, 2016
    In Google, there is no Enegon Battery Company and there is no 9V Lithium battery with a 5V micro USB jack and charging circuit in it.
    The battery and charger you plug the battery into are sold only by Amazon and they probably do not know who makes them (but we know where, China). They are guaranteed for only a few months so that is their lifetime.
    I wonder if they catch on fire when they fail?

    I think the 10 year Lithium batteries fail soon if you smoke, use candles and cook a lot.
  4. Ylli


    Jun 19, 2018
    There are smoke/CO detectors that are hard wired into the buildings power, right?
  5. Audioguru


    Sep 24, 2016
    Years ago when smoke detectors used a lot of power (vacuum tubes or TTL logic in them?) they were normally powered by the building's power but used a back-up battery of the power failed. Modern smoke detectors use very low power and modern disposable batteries power them tor 10 years (if they are not beeping). So the building powered ones are not made anymore.
  6. Externet


    Aug 24, 2009
    Like 25 years ago, a builder asked me to implement a smoke detecting system in like a dozen+ rooms in a Ripoffornia building -ooops- California-, were the then new 'code' was just being mandated and wired sensors were sustantially more expensive.

    Wired 9V ones them all to a trickle-charged lead-acid motorcycle battery with a 7809 regulator as supply. (Power-failure proof, permanently powered, chained to any trigger all alarms)
    The battery died like 4 years after, needed replacement, no big deal. I believe is still working...

    Now the 120VAC powered with 9V battery included are sustantially cheaper. And in the disposable society, now they want you to buy new ones instead of replacing the 9V battery and dispose Americium to the garbage can.
  7. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    I've been told by experts from the fire department that after 10 years the sensor in a typical smoke detector has lost so much of its original sensitivity that it needs to be replaced. Therefore the combination of a 10 year lithium battery with an equally long lived sensor is a sensible choice.

    The usual suspects from China sell this kind of battery and a few more in AA form etc.
    While the idea is quite neat (no separate charger required), in my opinion this technique gives up valuable space for the relectronics required, space that is no longer availabe for the battery chemistry.
    You probably get more bang for the buck when you use standard rechargeable clees and an external USB powered charger.
  8. davenn

    davenn Moderator

    Sep 5, 2009
    Maybe in Canada ... but not in many other parts of the world .... it's the law for all rental properties to have hard wired power
    to smoke detectors
  9. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    In Germany we have batttery operated smoke detectors - only recently newly installed by the management.
  10. Tha fios agaibh

    Tha fios agaibh

    Aug 11, 2014
    I'd see if it can be moved to another location. Perhaps next to a loft or balcony where it can be reached.

    Incorporating a charger isn't a good idea because people may use the wrong batteries.

    In USA, smoke detectors must follow local building codes. For construction after 1991, most communities require dual power (Household and battery backup), and be interwired so that all smokes go off if one is triggered.
    If your in an older home, code may be "grandfathered" with battery only operated smoke detectors allowed, but are usually required to be upgrade when the residence is sold.

    Ask your local jurisdiction about your options. If you have an alarm system that monitors the detectors, you may be compliant and not need that detector.
    (Most alarm panels have backup batteries easily accessible).

    Due to dust and grime alone, smoke alarms should be replaced within 7-10 years.
  11. dave9


    Mar 5, 2017
    Your post makes no sense. If you have to replace the battery once a year, you are the very last person who would be a candidate for a rechargeable battery.
    davenn likes this.
  12. Bluejets


    Oct 5, 2014
    The way things are currently in Aus is dependant on many factors.
    Things will change over the next few years as new laws come into being. (2027 I think it is)
    Hard wired in rental currently is for accessible locations. When inaccessible to the building wiring, battery are acceptable.
    Currently we use the 10 year in that situation anyhow.
    New domestic or domestic when sold is all hard wire with replaceable dry 216 alkaline and the number and placement another variable depending again on many factors. Currently with new, we fit one to each bedroom and one at an egress point for single level and again we tend to go for the 10 year battery there. Locations are a part of the engineering plans for each premises.

    I can see a point where certification will become a factor when renewing any household insurance, much like the real estate requirements for electrical standards when a property changes hands.
    Good move too as there are just too many inexperienced who love to fiddle and these really are a life saving device, the correct operation of which should not be taken lightly.

    12 monthly tests which we currently carry out on retirement villages and the like have proven the 10 year lifespan on any smoke alarm previously meeting the standards is still well within their operating range. So perhaps the fireman who said differently was quoting some Chinese brand fly by night manufacturer.
    All new units are also photoelectric, so by-by ionisation.
    Ironic really because the photoelectric is where we started 20 or 30 odd years ago.
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