If anyone experiencing the "running out of battery" scenario a lot, please bring up the issue with me. I consider this an issue.
Let me share my design consideration for my sensor.
My intended design for the sensor is for a daily driven car. The battery should be filled during the drive. The battery capacity based on my recommendation (300mHA ish) should allow the sensor running for 1 month on battery by a conservative estimate. My intention is to have a configuration(setup) where it is very unlikely to run out of battery. The 1 month buffer is a lot for a daily driven car. However, I want to take into account some time that we take vacation. On average, I would say that 2 to 3 consecutive weeks vacation in a year is expected.
In any case, additional rule like @aaiyar's is always welcome to close the hole in the implementation.
I'm only trying to figure out best implementation. Even if one usb (I have usb outlets in my car) to be able to leave it plugged in and powered at all times would likely be a good solution for me as I could combine it with my cell similar to @aaiyar for unlocking doors (I have a detached garage that I can't use for my car)...
@rlithgow1 Just FYI, I think I have mentioned it to aaiyar here if I am not mistaken. My sensor will work differently between DC and Battery power. I personally am not recommending to have the sensor charged all the time on dc. The obvious reason is one the capability to detect whether the car is powered up. Code wise, I optimize the code base on the power state.
Of course, I do not know all the scenario that you may want to use my sensor. I will try to accommodate how you will be using it. Hopefully, it would not conflict with my design.
I have one of these types of connectors (not this one specifically - I just picked one at random…) in each of my vehicles for the Dashcam. they are pretty easy to install and work very well. You can chose to install with a fuse that is always on, or one that turns off with the car.
If the arrival sensor is capable of measuring the voltage of the connected power supply, you could use the always on power and still have the advantages of both the "car running" detection AND skip the small Li-Ion battery. Most cars will have an alternator output voltage over 13.5 volts and a typicall lead-acid battery voltage will be 12.6-12.7 at full charge.
Just FYI, I am in the process of ordering a prototype board that would be powered by 12v battery. It will come at some point. But, It will take some time.
Measuring the power source voltage to detect the car state is in my consideration. However, I will have to make sure that it is not consuming too much power. It is a polling mechanism. There has to be extra timer that schedule this voltage reading. I just need to measure the power budget for this mechanism is reasonable. Coding for a ZigBee end device require abit different approach versus Arduino. It prefer to sleep as much as possible to conserve power. It is preferable to wake up on specific event when possible versus waking up at certain time to poll and back to sleep.
I do have other idea which does not involve polling to explore.
I am in the stage of r&d for the 12v version. But, the final product would involve tapping to fuse box. For some of us, this can be exponentially more challenging than plugging a device to a usb port. This is why I think the USB powered version is still valuable in any case.
Have you by chance investigated any sound detection that could be added to any of these wonderful devices ?
Or does someone know of an existing solution?
Use case: my teenage son will sometimes stay up late playing his video games. So long as his school and chores are done I don't mind too much.
However he will sometimes allow the volume to drift up very loud for 1 am and such.
So I would like to have a sensor listening. When volume exceeds a certain threshold give a warning through tts. If e continues to leave the sound up I want to cut the power to his TV and pc speakers.
The logic shouldn't be hard to setup though I am not sure I have seen such a device.
Sound detection is an interesting IOT topics. I always am interested on this topic. Personally, I have been playing around from rudimentary sound detection to more sophisticated AI sound recognition. This is a very broad topic.
For you case, what you probably need just a sound meter. If I can find the link, I will share it here. I found a module that convert sound pressure level to an analog voltage. You can use an Arduino or my Environment Sensor with this module to monitor the sound in the room. You cannot differentiate the sound from your sons playing a game or some other sound. It just measure the sound level or the room.
I have received the latest batch of Arrival Sensor. It is the latest released version of the sensor. In this batch, I have a small quantity for all of us who are interested on using the sensor. They are professionally assembled by contract manufacturer. I am very happy with the quality that they have done.
I have request from members here about the Arrival Sensor. I will try to go through my note as best as I can. I am hoping that you are all can do me a favor to reach back to me as well to me if you are interested on the module. I may missed some of you in this process.
I updated the first post with all the information about the sensor. I have gotten feedback that my post could get long. I want to make sure that I maintain my first post with all the information about what I make so that we do not need to read through all the response here to find out about the sensor.
@aaiyar, Thank you for your kind words. I really appreciate giving it a try. I hope it will be one of many devices that make our experience with smart home, Habitat specifically, better.
I learned recently that your environmental sensor is now directly supported by zigbee2mqtt, and I moved two of mine to z2m. Is there any possibility that you can add z2m support for the arrival sensor also?
