Iman,
Have you considered making a 12V version instead of a 5V version of this? Use case: direct wired into the car ignition on circuit so you don't have to have a USB converter permanently plugged into a socket.
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Hi Ashok,
I am not trying to be negative, but wanting all things to be equal. When you did your testing with the SmartThings arrival sensor, was that before or after your antenna mod?
And sorry to hear you hurt your finger.
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I don't have the zigbee antenna modified. Only Z-wave. So they're tested equivalently.
Trying to unbox a Weatherflow Tempest 
Cut pretty deep, but it'll heal.
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Thank you for the clarification.
Geesh. Cut yourself opening an new toy. That REALLY sucks !!!
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You asked a good question. Here's a direct comparison of the two. For my last three arrivals. I cannot compare departure because the timeout is different.
Iman's Arrival Sensor = "Ashok's Car Arrival Sensor"
SmartThings = "Ashok's Car Presence"
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Yes.... I have started a design for a sensor that will use the 12v power. It will be permanently powered from the 12v.
I will have a few early prototype board in a few weeks for this version. I will have to source the components. It could take sometime to get it to the point where I can share it here. But, it is in the work.
Electronically, it is a bit more challenging. But, the software side will be very close between versions.
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Thanks for the update @aaiyar.
Just FYI, I did start this project with the motivation to automate the garage door. As the time goes, I am also happy to have the additional sensor setup for my cars parked on my drive way. I started to integrate the motion and shock sensor event to my home lighting.
My Youtube feed somehow pop this to my attention. Here is a Canadian reporting on car theft. It is not as sexy as "Gone in 60 seconds". But, it is quite eye opening. Many car is stolen under the watch of our camera. One of the comments that stick to me is that they find out the car is gone in the morning. It is a long video. I link it to the part that is interesting.
My sensor may not be able to prevent the theft. But, I hope that with the help of my house lighting I can set up something to scare the thieve. If the car is stolen any way, I am notified as soon as possible (not the morning after). I hope I am giving my car and myself a fighting chance.
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I love this idea- and the shock sensor is very sensitive!
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I think it would be wise to have much more intrusive notification if the car is powered on between 12 AM and 5 am in the morning. At least, it is very unlikely for me to drive that time of the hours.
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Maybe even tie this sensor in with HSM? Although the neighbors might not care for an outdoor siren.
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@aaiyar Can you post a copy of your arrival rule with @iharyadi 's sensor? Trying to see how to best use here and examples help me
It’s in NodeRED.
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How do you prevent your garage door from opening if the battery goes out (obviously changing the device to not present) then being powered up and showing present (tripping garage door) (Hope you're finger gets better soon!)
Presence only opens the door for the first 5 minutes after the mode changes to Home.
Mode changes to Home based on an OwnTracks geofence that is about 300 ft. So my garage will only open if my phone is with me.
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So if phone is present (via own tracks) but the fob goes dead from battery (not present) since you're already home with the phone the door doesn't react. But if both go not present and then both go present and phone changes mode to home then door reacts?
Correct. And phone will precede the arrival sensor by about 20 seconds.
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Antenna size matters a lot. For best performance, a vertical antenna should be 5/8 x wavelength of the RF signal. However, 1/4 wavelength antennas can also be used. If the length is shorter than 1/4 wavelength, the performance will be poor. That is the reason that antennas crammed into boxes such as key fobs and Hubitat hubs contain a suitable length of wire wound around a toroid core.
I am an amateur radio operator who operates in the HF, VHF and UHF frequency bands. The UHF bands range from 300 MHz to 3 gHz. Thus, the frequencies used for Z-wave (around 908 mHz) and Zigbee, WiFi and Bluetooth (around 2.4 gHz) fall into the UHF spectrum.
Wavelength in meters is calculated by dividing the speed of light in meters/sec by the frequency in Hz.
Thus, for a frequency of 908 mHz, the wavelength is
299,792,458 m/s / .000908 Hz = 0.330 meters
Thus, a 5/8 wavelength antenna for Z-wave would be 0.206 meters which is
For Z-wave, the appropriate length for a 5/8 wavelength antenna would be 206 mm or 8.11 inches.
For a slightly less effective 1/4 wavelength antenna, the appropriate length would be .0825 meters, 82 mm or 3.2 inches.
I have seen posts indicating that placing an 8" piece of copper wire vertically as close as possible to the internal Z-wave antenna in their hubs or devices can improve the signal strength.
In a similar manner, the wave length for the 2.4 gHz frequency can be calculated as 0.125 meters.
For Zigbee, WiFI and Bluetooth, a 5/8 wavelength antenna would be 0.078 meters, 78 mm, or 3.1 inches. A 1/4 wavelength antenna would be 0.031 meters, 31 mm or 1.2 inches. Many routers will come with 5/8 wavelength antennas to maximize range while many bluetooth devices often come with only 1/4 wavelength antennas.
Most Zigbee and Z-wave devices have internal toroid wound antennas. Signal strength can be improved using either a passive or active external antenna of appropriate length.
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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.
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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)...
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@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.
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