Evaluation Type: Independent Products
Did you receive all parts the manufacturer stated would be included in the package?: True
What other parts do you consider comparable to this product?: null
What were the biggest problems encountered?: One sensor didn't ID correctly, but was fixed.
My proposal for the EnOcean IoT pack was to monitor the cost of opening and closing a refrigerator door by analyzing the heat transfer while the door was opened. The proposed system is displayed in Figure 1. The magnetic contact switch monitors when the door is opened and for how long, while the temperature sensor monitors the ambient temperature. With these values it should be possible to do a heat transfer analysis and determine the cost associated with opening the door.
Figure 1: The proposed monitoring system installed on a typical refrigerator. The EnOcean wireless temperature sensor and the EnOcean magnetic contact switch monitor the ambient temperature and the opening/closing of the refrigerator door respectively. A Raspberry Pi runs FHEM (data logging server) and logs events like opening and closing the door.
It took no more than 4 hours cumulatively to perform all the above and get the log files.Tightvnc wasn't rendering the contents of the Midori web browser properly, so I had to install Chromium. Figure 2 shows the screen shots I took so you could see the rendering issue. I also changed the style of FHEM to dark, because it looks cooler.
Figure 2: FHEM rendering issue from Midori.
The sensors have been logging data for nearly two weeks now, and the batteries still have a charge. I thought that because of the location (inside a home) that they would eventually lose their charge and need to be relocated for charging, but that hasn't happened yet! I finished the analysis of the heat transfer data acquired and blogged about at the following two links:
I could re-post the information here, but I don't see a necessity to double publish it since it has already been provided on Element14. The results of the analysis show that at the worst it would cost maybe $7 a year to open your refrigerator door. When I say worst, I took the largest heat transfer coefficient I could find for air to do the analysis.
My Thoughts (Conclusion?)
This review is short because the product works as it should. There were no major problems, and the system made by EnOcean is fantastic to say the least. I am overly impressed with their product and accompanying documentation. It’s really tough to get near perfect scores for a product from me, but these guys really deserve it for this product. The only problem that occurred happened when I was installing the sensors into the FHEM environment. The temperature sensor did not ID properly, but after a quick check of the documentation the problem was easily resolved. It’s also great that these sensors don’t require an off-board power supply (they use solar cells to self-charge). Sometimes it’s refreshing to find a product, especially targeted towards engineers, that works as it should with minimal effort out of the box.
(to be continued?)