Elgato Eve sensors: Review
Sensors are a category of devices that play a fairly pivotal role in any smart home. They broadly provide the ability to monitor the state of the home environment, and the input to trigger events in a more intelligent and reactive manner. Without these kinds of devices, automations are limited to scheduled, geofenced, or manual initiation.
With the introduction of HomeKit in 2015, the German company Elgato was an early bird in terms of getting devices to market with their Eve line that exclusively supports HomeKit. Indeed, Elgato was a pioneer in getting devices based solely on Bluetooth LE to work with Apple's strict security requirements. They continued to roll out additions to the product line and now have a useful range of 11 (as of June 2017) dedicated sensor products for Apple users.
Connecting the devices to HomeKit is simple. I've used the Eve app to do this after powering them up with either the included batteries (in most cases) or plugging them in (with Eve Energy). Once the device is on, Go into the Eve app Settings tab, tap Accessories, and then the + button. The app will search for any unpaired Eve devices and display them. Select the one to add and you'll be asked to scan the HomeKit pairing key (each Eve device has this both on a label on the device itself, and on the inside of the packaging) with your iPhone camera which will start the pairing process.
Once the device is paired, the app will guide you through naming it, adding it to a room and then you're good to go. As all of these devices use the same connectivity (Bluetooth LE) I'll jump into a more targeted review of each specific function and their performance.
This was my first entry into the Eve products as I needed a motion sensor for a planned nightlight automation. The Motion, as with most of the Eve line, comes in the form of a mostly square block about 8cm across and 3cm deep. The back is flat, its only feature being the battery cover, while the front is punctuated by the fairly recognisable standard motion sensor lens.
The Motion provides a single function, passive infrared motion detection. This works like any typical alarm sensor by detecting the variance of heat across its field of vision, and has the option (enabled through the Eve app) of flashing a red LED when motion is detected. Elgato claims it works best detecting motion moving across the field of view rather then towards or away, but I've found it equally effective in either case.
The app provides the ability to set 3 sensitivity levels, low, medium, or high. I found medium to work fine but with some inconsistency. The high setting was much more reliable, and I've stuck with that.
Elgato indicates an average response time of 2 seconds to trigger an event. It's unclear whether this is on the device side, or the HomeKit side. Probably a bit of both as there would be some latency between reporting to HomeKit and the communication going out to the relevant devices to be triggered. The reported response seems on the money though. I have set the Motion to activate a nightlight scene on some of my Philips Hue bulbs, which come on about the 2 second mark, give or take....most of the time.
This brings us to performance in general. I was actually pleasantly surprised that it worked at all, given the range to my Apple TV hub. The Bluetooth LE manages to communicate effectively through a couple of walls across a straight-line distance of 20 meters without issues. Given the response time is on the money, the only real issue I have is that, occasionally, the scene doesn't trigger. Nailing down the cause is tricky, but I'm more inclined to point the finger at HomeKit for now as the Motion does register the event.
Overall, it's working as advertised, simple to set up, an trivial to configure in the Home app to trigger events. The response time isn't fast enough to provide 'follow me' type lighting, but for less time sensitive applications it's an easy and effective solution. It's also IPx3 rated, which means (mostly) rain resistant, so it can be used outside to an extent.
Eve Door & Window
The Door & Window sensor covers another common and very useful sensor category that offers a lot of flexibility for automation scenarios. Long used in home security systems, these sensors use a magnetic reed switch to determine the open or closed state of a door, window, gate, or other opening. This type of sensor also provides a basic status function, and as Elgato has enable notifications on these sensors through the Home app, they can be used for simply keeping track of whether doors and gates have been left open or not (or indeed if they are opened while you are out of the house)
The Elgato offering is very compact, with the battery and logic in the larger part, and a small magnet in a flat, square casing. By placing the two parts of opposing sides of the door or window, the sensor can report whether it is open or closed by whether the magnet is in proximity to the sensor or not. Both parts have an adhesive backing strip already applied out of the box, so it's trivial to attach them once a suitable location has been identified.
The sensor is battery powered, using a 'half AA' ER14250. The battery us easily replaceable, as the sensor unit can be slid off the backing plate to access the battery compartment. My major concern with the design is that the placement of the battery forces the sensor itself to the 'top' of the case, the furthest from the attached surface. This means in a scenario where the door and the frame are flush (I have to think that's common), the magnet portion needs to be raised significantly to align with the sensor.
Elgato does provide for this by including a number of snap-together tiles that sit under the magnet piece to adjust the height as required, but it can mean the small magnet is sticking out quite a bit from the frame. I've tried to show this arrangement in the photo; The top of the sensor and the top of the magnet need to be flush (both have a rectangular marking to show the facing surfaces for alignment purposes). This is mostly a cosmetic issue, I admit, given the placement would usually be in a corner out of the way.
In terms of performance, I've found the range to be surprisingly good, being able to communicate effectively with my Apple TV hub across most of the house, at a range of about 30 meters. The inter posing walls do contribute to some delay though, and it can take several seconds to update the status of the sensor. I believe the physical limitations of the placement also result in some unreliability, with my associated scenes not always firing as expected, even though the status of the door does change to Open or Closed as it should.
The Room sensor comes in a the same general case as the Motion, a simple rounded square that can be placed anywhere in a room to provide environmental sensor data. The room is a little on the pricey side, but that is due to the VOC (Volatile Organic Compound) capability which goes above and beyond some others in determining the air quality in the room. Elgato says the device includes a MEMS sensor that "detects and measures VOCs such as alcohols, aldehydes, ketones, organic acids, amines, as well as aliphatic and aromatic hydrocarbons".
In addition the VOCs, the room provides the usual temperature and humidity readings. From a HomeKit perspective, these three aspects present as three distinct sensors that can be displayed and used to trigger events and scenes. Simply including them as favourites in the Home app can be useful for monitoring the status of a room, a child's bedroom for example.
In my case, I've done just that with my daughter's room. This was a useful test case as it is literally the opposite end of the house to the Apple TV I'm using as a hub. I was virtually certain the Bluetooth connection had no chance of getting through in any reliable fashion, but no, I can consistently get up-to-date data from all three sensors from work on demand, although there is some update lag. For passive monitoring this is completely workable, but I'm yet to try associating automations with the sensor readings on this one, mostly due to a lack of suitable devices to trigger.
The Eve app provides nifty historical graphing of events for all their devices, but I feel it's worth calling out in this case as this kind of sensor data is perhaps more interesting from a trend perspective. All three sensor values are there individually, with detailed time indexed results.
The smart plug category is a key one in the smart home as it allows for various 'dumb' devices to be controlled in a rudimentary way. HomeKit has a number of smart plug products available now, with Eve Energy being one of them. Most of the smart plugs provide a useful secondary function, to measure energy usage. Elgato augments this in the Eve app by allowing you to specify your tariff per KW which it then uses to give you a running cost and projected cost for that plug, as well as a total for all your Eve Energy devices, assuming you have several.
Elgato provides models for all the common power socket types globally, which distinguishes them from many of the competition that cater to the US only. The Energy comes in the common Eve square form factor (except for the European E/F type, which is instead deeper), with a small LED/button off one side of the socket on the face to provide manual override and a power on indication. Obviously, this is one Eve product that is not battery powered, it draws directly from the socket.
The case size is an issue here, in that any use in a multi-gang wall plate or power board is going to crowd out the neighboring sockets. This is a common issue with most of these smart plugs, but there are some better designs going (the Koogeek Smart Plug P2 for example) than the rather wide option Elgato has chosen for most of the supported socket types.
That minor gripe aside, the Energy works as advertised. I've had no issues with responsiveness, and it switches on and off via manual triggering (via the Home app or Siri), or associated with scenes very reliably. One issue that has become apparent is that the pins inside the unit (that grip the prongs of the power plug once inserted) are quite close together and tight. It is possible to miss align the insertion of the power plug and bend the pins, rending the device useless. It is possible to open the unit (held by two screws on the back), and bend the pins back, but that's obviously not recommended. It's more something to be aware of when inserting the plug, don't force it.
Elgato has a growing range of practical HomeKit specific sensors that provide an easy way to add monitoring and automation to your smart home. The use of Bluetooth with HomeKit has been a challenge for manufacturers to get off the ground, but we're now seeing many more devices coming to market primarily using this protocol, and as a leader in this space Elgato has demonstrated a surprisingly reliable implementation. Obviously range and interference are still factors when using Bluetooth devices with HomeKit, so factor the proposed placement into any buying decisions, but I've found the Eve range to be usable over a much greater range than I anticipated.