Door/Window sensor setup for cold environments

I recently acquired a battery powered window/door sensor (Samsung OEM). I wanted to install this on my shed door in the corner of my backyard. The shed is close to max distance from the hub and also in the low temperatures of Wisconsin. I did not want to worry about battery life so I wired a power transformer/brick to the sensor. I wanted to share some images and list the devices I used encase someone else has a need for placing sensors in cold environments that may drain batteries.
Example: Garage, coolers/freezers, sheds, etc.

Product idea’s came from other threads on this forum.
ZJchao 3V 1A AC Adapter to DC Power Adapter 5.5/2.1mm
This power brick outputs 3v (same as the battery in most sensors). I cut the end close to the factory adapter and spliced back the wires.
The brick came with another adapter which I cut both ends off and used it to create a pig tale. The pig tale is what you see in the pictures coming out of the sensor. The wire is soft and easy to work with. Having the pig tale allows me to easily remove the device and its case, encase I need to service it down the road. I did not want to hard-wire everything together.

I was able to use a multi-meter to determine the + and - of the power adapter. I switched my multi-meter to DC and place the red and black probes on each wire until I had a positive 3v output. If you place the probes on backwards the output would be -3v.

The Samsung OEM sensor is clearly labeled + and - when you remove the battery.
I drilled a small hole to accommodate the internal wires of my pig tale (see picture). Ensure you drill the hole on the opposite side of the markings on the sensor. The markings point to the side where the magnet needs to interact with the sensor.

I then stripped and fed the pig tale wires into the sensor and solider them.
I measured and marked the cover. I used a drill bit that was just slightly larger than the outside seething of the pig tale to ensure the cover snaps back in place and to allow the cable to slide encase I need to reset/service the sensor.

When powered on the sensor reports 100% battery life.
I used 18/2 thermostat wire to connect the sensor pig tale to the power brick/ transformer.
I was able to hookup two sensors to the single power brick without issue.

Other idea is to utilize a larger power transformer/brick with several of these devices.
LM2596 DC to DC Buck Converter
This would allow you to have a single source of power and then step down the power to each device. Allowing you to wire an entire area from one location/power outlet.


Nice write up.
I am curious: what are you doing too avoid problems from moisture/condensation in such an environment?

I’ve had 2, not even sure of the brand in 2 sheds for over 2 years, still using the same batteries. -5 this am.

1 for the garage door as well, it read 15 above from another sensor - fwiw.

Someday I’ll replace one of the shed ones with one with temp readout.

The sensor is inside the shed. I do not expect drastic/rapid temp fluctuations where condensation would be an issue. The sensor itself does not put out enough heat to form condensation - at least not that I can tell. If I were to remove the sensor and bring it inside my home that has 38% humidity and 70 degrees warmer temperatures I would let the sensor ‘warm up’ naturally (without power) before I attempt to service it. Just follow the basic rules of technology when transitioning from cold to warm environments and vice versa.

That is awesome, unfortunately I am not as lucky. I placed my sensor on my back porch for a few days and the battery reported 84%. Bringing it back inside and letting it warm up brought it back up to 100%. I didn’t want to deal with that type of situation in the long run. I am not too familiar with these devices and if they consume more power the further away they are from the Hub (like a cell phone with low service).

You probably don’t need a larger brick. The draw on these sensors is puny. Many could probably be run in a daisy chain, and supply all the power any/all of them ever need.

What is the amperage of your current brick?

I agree with you. 1A is current output for brick.
I was offering an alternative option encase someone has a setup that, for example, needs 3.5w and a device that is 2w. You might not want to provide 3w power to those devices if their needs vary among brands/types. The Buck Converter allows a user to adjust the output specific to the need.