SmartThings Community

Plugged in - Z-Wave Motion + Temperature Sensor

(Brandt) #21

Do the plugged in sensors report temperature and light levels more often than the battery powered ones? I need something that knows more quickly whether a light is shining or not…


The reason I am looking for a plug in motion sensor is because in the garage it gets cold and batteries don’t last two minutes in cold weather. I have a battery powered one in their now and the battery is going down so fast compared to other sensors inside the house.
I brought the garage sensor inside and suddenly the battery life is now fine.

(Vi) #23

A USB Plug-in adapter +

(or similar) should solve the problem.
You’ll need to solder a couple or wires but the sensor can be placed anywhere.

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(Jim Gaudette) #24

So get a 12vdc (or within the range) power supply and insert this between the hot side of the power supply and the positive terminal of sensor, then common of supply direct to negative terminal of sensor???

Are thermostats run off 12vdc? Be a nice place to put sensor and easy to grab 12v (since we had to run a common for the smart ones already anyway)…

(Vi) #25

Yes, you connect -PS to Common of Regulator and to ‘-’ of the sensor.
+PS goes to Regulator IN+.
Regulator OUT+ -> ‘+’ of the sensor.

Known to me thermostats run on 24VAC. You’ll need a rectifier + filtering capacitors. Regulators with wider ranges of Input voltages certainly exist but I am not sure they will easily go into the sensor’s battery compartment.

(James) #26

Thanks for the link. Just ordered two to see if I can get the arrival sensor on the 12V from the car.

Those are a battery drain especially when it is cold out.

(Robin) #27
(Thecolor Cypher) #28

give me your thoughts on this…

I recently purchased this 4V 100mA solar panel

(which I know never runs full power unless in direct sunlight) - this is behind glass/inside/facing out.

and these 3.6V LIR2450 coin cells

and soldered the s-panel to the sensor. Stupid simple. BUT…

What problems (if any) do you foresee? I know enough about electricity to be “dangerous”.

My goal is not to replace the power ('cause clearly that would only work on a sunny day).
Instead, to keep it topped off.

If it can maintain a full charge, then cold dips and constant replacements would be a thing of the past.

At the moment, it’s working fine AND the battery is fully charged, so I won’t know for a while… BUT, the sensor is constantly in use (multipurpose motion) in a high traffic area.

Let the flames begin! (you only learn by failing) :smiley:

(Robin) #29

In order to charge a rechargeable battery, you need protection circuits, to prevent over charging / fires / death & brimstone.

Unlike some large rechargeable batteries, button batteries do not contain this circuitry, so instead the charging device must include the protection.

Soldering a solar panel directly to a sensor, in parallel with a battery, is not a good idea at all!


The problem is, as Robert Heinlein pointed out many years ago:

stupidity is always fatal. Unfortunately, it doesn’t always get the right person. :scream:

This is particularly true for fire safety. For the sake of all your neighbours, some of whom might need assistance to evacuate in the event of a fire, find another way. :rotating_light::fire_engine::ambulance:

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(Thecolor Cypher) #31

so, is it logical to assume that a button cell and a solar panel in a 2in plastic box is likely to catch fire vs melt or just short?

Just trying t become less stupid. :wink:

1 Like

A short always represents a fire hazard.

But, yes, batteries do burn. As Samsung knows very well. :disappointed_relieved:

(Thecolor Cypher) #33

Would either of you have a suggestion for the smallest protection circuit I could place in between without to much bulk for the two items above?

(Thecolor Cypher) #34

side note… I also considered cannibalizing a refurb I bought of my fav keyboard:

Thinking it might have everything I need and charge under better circumstances.
However, the b-cell is a 2032 instead of the S.T. 2450… so I wasn’t sure if it would be a straight up swap and just charge slower.

(Thecolor Cypher) #35

also… is it likely the battery will ever be full, what with the constant use of it as a multipurpose device?
That’s where my mind org. came from as, expecting it will keep it “topped off - lose term” but never full or “over” even for a rechargeable.

(Robin) #36

The sensors use minimal battery… in some circumstances lasting 6-9 months… so yes, they could certainly become full.

Why are you considering this option at all? Button batteries are dirt cheap. You’ll need to clean the solar panel more often than you would have had to change the battery.

(Thecolor Cypher) #37

honestly, I’d be lucky to get 6-9 months. WA state.
'specially in the cold months.

The device(s) bat threshold seems to be SO low, that I get false positives all the time if the battery is not brand spakin’ new! :confused:

The only bats that last that long (of all my S.T. device(s)) are the leak sensors.
*likely 'cause they are a bit more insulated.

Needless to say, it’s a little frustrating.

Which ties into why and cheap… 'cause constantly replacing them with something that came factory full vs always “topped off -loosely”, seems more accurate, useful and less a PITA.

As for cleaning the panel, it’s in the window (inside the house)… so it’s not going to get dirty easily/less rare dust.