Connect with us

Replace 9Volt Battery with Solar Panel

Discussion in 'General Electronics Discussion' started by rabbithutch, Jun 22, 2018.

Scroll to continue with content
  1. rabbithutch

    rabbithutch

    5
    0
    Jun 22, 2018
    Howdy All!

    I'm new to electronics (at age 76, still trying to learn) and new to Electronics Point; so please be gentle.

    I have some motion detectors on my property that operate from common 9 VDC batteries. They are located on gable ends nearly 20' above grade level. Replacing batteries requires climbing a ladder. SWMBO doesn't like to see me on a ladder and to tell the truth I don't do it nearly as well as I used to do; so I was wondering if it might be possible to install a small solar panel for each detector to displace the batteries.

    I've found some Radio Shack new old stock panels that produce 12 VDC at low amperage. Is this a doable/feasible project?

    Thanks in advance.

    Admins: If I've posted in the wrong place, please move the post appropriately and send me a chastising note.
     
  2. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    Good for you, and welcome to the forum.

    You need to determine how much current the motion detectors use. As an aside, what do they do when they detect motion?

    Do they have to operate after dark or on cloudy days? If so, you need to have a battery that is charged by the solar panel for operation when the sun is not out.

    Bob
     
  3. rabbithutch

    rabbithutch

    5
    0
    Jun 22, 2018
    Thanks, BobK!

    The detectors send an RF signal to a receiver inside the house that uses mains current to emit beeps. The number of beeps indicates which detector was triggered.

    I hadn't thought about needing to charge a battery for those times the sun isn't shining, but it certainly is logical. The detectors use regular 9V DuraCel (lead-acid?) batteries which, I believe, are not meant to be charged. What sort of batteries should I shop for that are meant to be charged?

    Thanks again for such a prompt response.
     
  4. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    NiMH batteries would be best for this application. They are 1.2V so you can't actually get 9V, 8 of them will give you 9.6V. Then you need a battery management system to charge them. It is really not a simple project.

    Bob
     
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,496
    2,837
    Jan 21, 2010
    The simplest solution is to use a battery technology that will cope with float charging.

    Lead acid and lithium batteries tend to fall into this category, but both require some battery management. Whilst there are ways of doing this relatively simply, it's still relatively complex compared to batteries.

    A simple solution may be to extend the battery leads out and place a battery box at a level which doesn't require you to climb a laddar to change the battery. In this case of also fit a capacitor up at the sensor to help head off potential problems caused by the long run of wire.
     
    ChosunOne and 73's de Edd like this.
  6. Bluejets

    Bluejets

    4,833
    1,017
    Oct 5, 2014
    Time spent up a ladder doing the mods wouls seem to me to be far in excess of simply replacing a battery now and then.
     
  7. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    But more dangerous. And around here a real bitch if there happens to be 3 feet of snow on the ground.

    Bob
     
  8. ChosunOne

    ChosunOne

    404
    115
    Jun 20, 2010
    If you use Energizer's (or equivalent) Lithium 9V non-rechargable battery, it would extend the time between battery changes, probably by several years.

    I'm familiar with security system RF (wireless) PIR motion sensors that send signals to RF Receivers that pass them on to control panels that process and interpret them and have various notification/alert protocols, depending on the signals received (motion detected, low sensor battery, supervisory trouble {i.e. not hearing from sensor}).
    Virtually all North American RF PIR sensors in the alarm industry use lithium batteries nowadays, which typically last 3 to 5 years, for CR123 batteries or similar.

    I am not familiar with a system that sounds coded beeps according to which motion sensor was triggered. I suspect your system in not a security alarm system, but maybe a driveway or wildlife alert system or something; but of course, i could be wrong about that. In any case, not knowing the brand or model number number of your system and sensors, I can't guess how long your "normal" (I assume "alkaline") batteries will last, so I can't guess how much longer a lithium battery will last.

    The RF PIR motions I'm familiar with use only a tiny current draw for detection and use significant power only when they transmit. To conserve battery, they only transmit one signal every few minutes at most: Once a detection signal has been transmitted, the protocol is not to send another signal until the sensor sees NO motion for several minutes--thus, something constantly moving in its field of vision won't run the battery down.

    That's for the units I'm familiar with. I have no idea what kind of sensors are used in your system, whatever it is. For all I know, it uses microwave technology instead of, or in addition to PIR, in which case the batteries won't last nearly as long. Does your control panel or user interface tell you when each sensor needs a fresh battery?
     
    Last edited: Jun 23, 2018
  9. Externet

    Externet

    761
    166
    Aug 24, 2009
    Hey ! By 80 they take our driving licenses away; but by 60 they should have taken your ladder away !

    I would use a rechargeable 9V and connect directly a panel that supplies 9-10V.
    [​IMG]
     
  10. ChosunOne

    ChosunOne

    404
    115
    Jun 20, 2010
    That's a good idea, IF it's practical to run wires to the motion sensors;

    OP has implied a control center for the system, which most likely has its own low-voltage DC power supply somewhere, if it's anything like the equipment I work with. If running wires to the motion sensors is practical, I would use the control's DC power supply to drive a 9VDC power supply to the sensors.

    But I'm guessing here, since I don't know the kind of equipment we're working with. I _would_ find out, before spending money on redundant power supplies.
     
  11. Audioguru

    Audioguru

    3,305
    703
    Sep 24, 2016
    They renovated a nearby shopping center and put a large glass ball on top. When it gets windy the curved glass panels on it shatter. They replaced the broken glass and maybe all of it with plastic pieces.
    It takes them 1 week to put up a scaffold so that the 9V batteries in the smoke detectors can be replaced then a few days to take down the scaffold.
     
  12. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,496
    2,837
    Jan 21, 2010
    I would also consider contacting the local Mormon church, expressing some interest, and asking that they send some missionaries around to talk to you.

    When they arrive, have the laddar and all the other stuff out and pretend to have forgotten they were coming. Ask them to give you a hand while they talk. Tell them you're glad they came because you're not supposed to get up on laddar and that they should call 911 if you fall off.

    Then sit back while they do the job for you.

    They'll probably come back a few times, so make sure you have some chores lined up for them to "help you with" while they talk.
     
    ChosunOne and davenn like this.
  13. Externet

    Externet

    761
    166
    Aug 24, 2009
    Last edited: Jun 24, 2018
  14. Audioguru

    Audioguru

    3,305
    703
    Sep 24, 2016
    Using a solar panel then a battery charger circuit is missing and a diode is missing to prevent the battery from discharging into a dark solar panel.
    Energizer and other Ni-MH battery maunfacturers say the life of a Ni-MH battery is reduced if its trickle charge current is more than 1/40th its mAh rating. Then the trickle charge current for a 175mAh battery must not be higher than only 4.4mA that might be exceeded. We do not know how much current one of the motion detectors uses. The voltage from the solar panel is higher than 9V when its current is lower than its rated 112mA (and how bright is the sun?).

    Is Radio Shack still alive? It has been gone from Canada for many years and I keep hearing that in many states it is gone.
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-