The only other thing I can think of is battery level.
I ignore what is being reported (it’s quite often wrong for me)
Was it cold last night where you are?
If the battery is quite low then the lower temperature might tip it over the edge.
Brian
if you use them in the car then this mod works really well…
Been using three of these for the last 5 months will no problems (even in low temps)
1 Like
It was 31 degrees outside this morning. The garage is generally warmer, but I would imagine not by much… 
I’ll look into messing around with both sensors later on today or tomorrow. The Ford one still hasn’t returned, even though it’s been home all morning. I think I’ll bring it inside and let it warm up to test a theory, or perhaps swap the batteries for some 2032s I have here that are 100% new, just to see if it behaves differently.
good idea
let me know how you get on
BTW… Just uploaded update to my app to include control of locks & doors
Sorry, I haven’t been feeling well, and I haven’t taken the time to really look into this particular thread.
The Big Metal Box Issue
I will say, cars are always challenging because you’re talking about a big metal box, often with tinted glass, both of which degrade signal significantly. So getting signal out of the car to begin with can be complicated, particularly for low energy devices. It’s not impossible obviously, but it does add additional challenges.
Also, typically signal will travel very differently through an empty garage and one that has a car in it. Again, big metal box. this is one reason why people get a lot of erratic results, especially if they have two cars that go in the garage as now there are many different possibilities: no cars, car on the left but not the right, car on the right but not the left, one car coming in as another is going out, etc.
And of course local architecture variations. Garage doors, in particular, can have really different architecture as far as blocking signal. One with clear glass window inserts all the way across will typically have a much easier time than one which is either solid or which has tinted glass.
And of course different garage doors are made of different materials. Plain wood is a lot easier to get signal through than something with a fiberglass core. Or again a metal door.
For all of these reasons, I like to put a repeater near a clear glass window on the same side of the house as the garage. It can just make life a whole lot easier.
And again, all of this helps explain why different people report different experiences with the various different presence methods. 
.
Detection zone
There’s also the question of how big you want the detection zone to be, which varies from household to household.
If you want the garage door to be open before you get to the end of the driveway, you almost have to use phone based GPS Geofencing or Wi-Fi detection. Even though the SmartThings zigbee presence sensor as a range of around 15 m, it only checks in every 30 seconds. So you could easily have a 45 seconds to one minute delay before the garage door starts opening.
If you’re the sort of person who’s OK waiting in your driveway for the garage door to open, no problem. But if you’re the sort of person who wants the door open already as you pull in the driveway, the presence sensor probably won’t work for you. This is a personality difference, not a technical one, which again is why some people will be happy and some will be unhappy with the same technology.
My personal requirements are a need for hands-free operation, but I don’t mind Waiting a little bit. Which is why I personally use ibeacon detection. It’s very precise, and it is a little faster than the 30 second presence sensor, but, yes, I am sitting and waiting for the door to open each time. Which won’t satisfy everyone.
So before we start brainstorming specifics, if you could give us a little more of an idea of what you want the experience to be. You’re driving up in your car, at what point do you want the garage door to be all the way open? Before you reach the driveway, or after you’ve pulled into the driveway, but you’re OK with waiting a minute or two? This will significantly affect the possible solutions.
1 Like
Well I think going after “track the car to open on approach” is a lost cause, unless there’s some other setup I can use that’s more reliable, like a second hub at the perimeter or some other strange WiFi device.
Our pseudo plan already discussed of tracking the car’s presence in the garage and acting on it should work, on paper. As long as the sensor reports that the car is present, and the mobile sensor (phone, whatever) reports the person’s arrival, figuring out which door to open is easy.
I thought my problem would come from my phone not reporting early enough, but it seems that the issue – for now – is the car’s sensor lying. 
Right now my Ford has been out of the house since midnight (according to ST) even though the car is there. If I take the other car out and return, the logic would trigger the Ford’s garage bay to open, because the house thinks it’s not there. I haven’t even had to deal with inconsistency in mobile presence, because apparently “static” presence isn’t even working yet
OK, zigbee presence sensor “leaving” means it hasn’t been able to check in to the hub for however long your check in interval is. (You can make that interval somewhat longer in the IDE which is meant to help with devices with are right on the range of being able to call in, so they get a second chance to try)
Note that there isn’t any “I’m leaving” message for these sensors. It’s just the absence of that check in that then triggers the state to be changed to “away”
And this brings us back to the “big metal box“ problem. If the sensor is inside the glove box inside the car inside the garage (which probably has walls that are more like exterior walls than rooms in the house do) you’ve already got three barriers that can reduce signal. Which means increasing the likelihood that a particular check in message will get lost.
So now what other variables might cause the signal to not get through?
Wi-Fi is a big one. If you’re sitting and watching a Netflix movie, your Wi-Fi band is very busy and that can drown out zigbee signals.
Opening and closing the door to the garage from either side, opening and closing a refrigerator door, the other car being there or not being there, all kinds of things.
So the first thing to try is to get the sensor to have a clear line of sight to clear glass in the car, then pick up that signal with a zigbee repeater Inside the garage, then bounce it to a zigbee repeater Just inside the house.
My favorite thing to do is to put a plug-in pocket socket on an outlet on a wall that the garage shares with the interior of the house And then put another pocket socket on the interior side of that same wall. These two repeaters are likely to have a pretty good connection to each other.
I also like to put the presence sensor on the visor in the car as that usually gives it 3 window options to go through. And gets it up above the level of the motor, which is another big chunk of metal.
So as far as getting reliable signal from the car when it is sitting in the garage, try relocating the sensor inside the car and adding two zigbee repeaters, one in the garage and one just inside the house, and then extending the interval before the sensor gets marked as “away“ and see if that all helps.
Remember that you need to do a zigbee heal after putting the new repeaters in place or the sensor won’t use them.