Open/Close Door sensor based on acceleration



I’m trying to define a new wireless Open/Close door indicator based on an accelerometer or 6dof.
I’m trying to design it so it will last as long as possible without changing battery.

Is there any similar product y’all excised in the market?
What accelerometer do you thing will consume the least amount of Ampere? (and where I can check what is available and compare them?)

thanks :slight_smile:


These exist. Several manufacturers make them. The Kumostat wireless tags are popular and well engineered.

Also most “tilt sensors” can be used in this way. Even the SmartThings-branded multisensor could be used for this, although it would be expensive for this purpose.

Weatherproofing is very important for this device category, which is one of the things that the Kumostat brand has done well.

As far as battery draw, you just need to check the specifications for each model or write the manufacturer. It’s the radio that tends to draw the most power so the protocol matters a great deal. Zigbee smart power is typically the lowest, then 433 MHz, then Bluetooth low-energy, then zigbee home automation, then Z wave plus, then Z wave, and then Wi-Fi last. But there are individual model variations and some devices are designed specifically for low power draw while others are not.

The usual goal in home automation for sensors is that they last for year if they have replaceable batteries and 3 years if they don’t.

If intended for use in a home security system, however, the demands are usually for longer battery life, typically three years for a replaceable and 10 years for a non replaceable.

Security systems achieve the longer battery life by offering fewer features on each individual device. For example, Open/close detection devices specifically designed for security use often don’t include temperature sensors, and almost never include humidity sensors. You have to use a separate device, sometimes a plug-in, to add temperature or humidity detection to the security system.

So there is some market differentiation between security and home automation, although there’s obviously also a lot of overlap. Although people shopping for home automation typically say they want the longest battery life possible, they don’t really mean it – – they’ll often buy a shorter lived device that has more features. So you need to know how you intend to market it. :sunglasses:


thanks for the great respond! I’m looking to design it so the battery last the longest - so we can market it to the security systems market.

can someone help me with some insights about accelerometers that will not drain the battery, and what is the best battery options out there that can fit a small sensor?

Thanks a lot!


The sensor will have to work with a controller, so you have to select the network protocol with which you want to comply.

There’s a problem with security systems, though, which is that many of them use a proprietary network protocol as this is part of their security design. So consumers can’t just buy an off-the-shelf sensor and add it to most of these systems. So in that case you would be selling your product to the security companies, not the individual consumers. And that’s a very hard market to break into unless you have a new patented feature which would be of interest to them.

The home automation market is different, as there are some standard protocols and consumers do buy individual devices on their own. But the easiest protocol to adhere to is Zwave and that does not have the best battery life.

Why have you picked “long battery life” as the primary feature of your sensor? Is there a reason why you think you could compete with major companies like Centralite and 2gig? If people just want the cheapest possible sensor, they will likely just buy from Alibaba and get a noncertified Chinese device for a couple of dollars. So to compete, new companies like notion generally go for lots of extra features, versus shorter battery life.

By the way, notion is another example of a home automation sensor which uses an accelerometer. But they’re still in pre-release mode. Look at the number of features they are offering, though. That’s how most companies compete with the very inexpensive Chinese devices.


Thanks JD, I do know some guys in the industry. they work with RF 433Mhz
I’m looking to design a long battery life and cool design as I recognized them as too of the biggest issues with their existing product.


433 MHz is very popular for security systems. It’s a good choice if you think you can compete in the market. ( not compatible with SmartThings, though.)

There are specific issues that can come up. (For example, you can’t sell a 433 MHz device in Japan.) obviously antenna size, but there are others as well. The following is a good overview:

Note that it’s still very likely that popular security systems use their own proprietary encoding. That can complicate the issue if you don’t have the specs upfront as it makes it harder to predict packet size, and of course the more data you send the more battery power you need.


I’m thinking about offering both 433 and Z-Wave+ options (so i’ll include SmartThings home automation too). but I do need help choosing the MCU and Accelerometer (2-Axis will be sufficient for the Door Open/Close purposes).

Plus, I read there are some issues regarding heavy metal doors that disturbs the transmission - how should I approach that?


As I mentioned above, Z wave is easiest. You just buy their chip, it has an MCU with the libraries already installed. You still have to get the product certified, though. For 433, you need your engineer to look at things.

Personally I wouldn’t go with an MCU if you’re trying to optimize power consumption. They’re hardly the most efficient choice. But since you have to do your own FCC certification instead of piggybacking on Z wave’s, there are a lot of engineering decisions to be made. And most people would use different cases, even with a helix the antenna lengths are significantly different. And of course too much twist and you kill the range.

Like they say, hardware is hard. :wink:


Again, have your engineer look at it. There are multiple design decisions to be made and many factors to be taken into consideration. There’s no one right answer. :sunglasses:


So I sat down with one of the engineers
the two new q’s are:

  1. How can I reliably teach the system what is a “closed” door position and make sure I won’t have to recalibrate it often
  2. How do I get the accelerometer out of sleep mode (I want it to sleep so it won’t drain the battery)


For home automation and residential security, most sensors are not calibrated after they leave the factory. You just adjust the sensitivity. For the last few years, it’s been typical to use gravity to define one direction. The details of sensitivity adjustment will vary from model to model.

It’s also important to remember that even now most security systems are not DIY installs. There are literally millions more people who have security and home automation as a monthly contract with their cable company than have fully DIY systems like SmartThings. So again that means your customer is the security company, and their installer will do any on-site sensitivity adjustment using their software. So you have to meet their required parameters for time required and Precision.

For DIY home automation, there’s going to be a sensitivity adjustment step. Take a look at how Kumostat wireless tags handles it. It’s a good example for a typical power user.


As far sleep mode, that just depends on the individual device. There’s a lot of engineering around sleep mode. Most battery-powered Home automation devices are actually “sleepy” so that they sleep for a certain period, wake up and sample against a delta, then go back to sleep. So they sleep 90% of the time but in microsecond phases. On more expensive devices the phases are adjustable by the end-user. So it’s sleep, sleep, sleep, wake up and check to see if anything is changed, if it did change is it bigger than the reporting Delta, if it isn’t go back to sleep, if it is then report and go back to sleep.

Security systems sometimes work a little differently. A lot of them have the equivalent of a tamper alert where an event will wake them up. That’s just engineering. But of course the specifics depend on the exact hardware you’re using.

As far as sourcing, again assuming your goal is to sell 100,000 of these nobody’s going to give you a part number here except, of course for Z wave where there are only a few choices. You’re going to source the same way everybody else does who doesn’t hold a patent – – by negotiating with Chinese factories.

You don’t need to build a proof of concept, because these devices already exist in the marketplace. So you’re going to go right to the prototyping stage, and that depends on the specific hardware you’re going to use, particularly if your primary feature is power consumption. Your engineers should be driving your sourcing.

(Wes Tanner) #13

Anyone had any luck integrating an Ecolink Model: Tilt Zwave2 sensor with an iQ from Qolsys. I can pair it but it gives a message that it is not recognized by Qolsys…hoping someosne may have changed device types or has figured a workaround to get it properly integrated. Worked fime with Smartthings.


Not quite sure why you posted that in this thread, but as it happens, i do know the answer. :wink:

The QolSys IQ panel is an interesting device. Like the SmartThings hub, it actually is a single box that has several antennas inside of it.

It does have a Z wave controller, but it’s only intended to be used with lighting and a few other devices.

In the security category, including sensors, it uses 319 MHz.

They have a really interesting device called a “translator” which can bridge 345 MHz or 433 MHz to the QolSys-required 319 MHz. This let you use security sensors from other systems which are one of those two protocols with the IQ. But they have no similar bridge for Z wave.

That’s why you can pair a zwave sensor to it, but it won’t do anything with it.

For further questions, I would contact QolSys support. Or you can try the forums, they are very helpful and since they sell the QolSys there is a lot of discussion of it there.

(Wes Tanner) #15

Thanks for the info…FYI I have paired locks and lights with Qolsys Iq and using the app allows access to control those devices that are in the base algorithym for the larest release of software.


Are you familiar with an accelerometer based sensor that is being used in the security industry? I’m looking for examples and cant find.


Are you physically unable to use Google? That’s a serious question, I myself am quadriparetic and depend on voice recognition software, which is not always easy to use for technical research.

Anyway, they exist, you just have to look for them. As far as ones that I personally follow, I’ve been intrigued by Korner, which is a zigbee device but not compatible with any other system. Triangular sensor that fits on the door or window.

They have patents pending, which always gets my attention. You can buy it now at Amazon in a pack of three for $99 including the controller stick. They’re offering one year free service and then $39 a year after that; we’ll see whether that business model works for them.

But if the patent really turns out to be worth something, it may be that the business plan is to license the patent to other device manufacturers once it’s awarded, and the current system is more of a field trial.

More conventionally, I think pretty much every major security system has at least one accelerometer sensor as an option. Here’s one of Honeywell’s:

And again, many tilt sensors serve a similar function.

If you’re just doing market research, you can look for these yourself, but if you’re considering sourcing, have the engineers look. They’ll know the alternatives terms to search for and be able to recognize a hit when they find one.


Thanks for the help. I did search for it and even got the Korner sensors in front of me, Just hoped you can point me to new products I haven’t seen yet. I asked for examples from the security industry specifically as I haven’t found accelerometer based ones (only the SPD-2000 but for different purposes)
I do have engineers I can meet but before I do, I’m trying to “prove” it’s possible to get a sensitive enough solution that will indicate open/close position supported by CR123A battery that should last for longer than 24M.


Are you talking about with a gyroscope or not?


As I’m not 100% sure if I can fulfill my vision with an accelerometer (2/3 axis only, maybe with your experience you can help me answer that too), I’m not sure but i always keep in mind that battery lifetime is one of the big issues here