If you’ve never sat close to a bee hive and watched the little ladies going about their business, you’ve missed one of natures treats. They are fascinating creatures on their own and the social cohesion and workings of the hive make them doubly so. Bee keepers have always had to tread the delicate line between upsetting the balance of daily life in the hive against it’s internal state and the general welfare of the bees, though. We have traditionally had to open the hives on a regular basis to check on the health of the bees themselves, as well as the state of honey and food stores. While we still need to keep a careful eye on the health of the bees, IoT and ingenuity are making it easier to look after the bees without having to disrupt the hive with such frequent openings and I was very pleasantly surprised to come across the OpenHiveScale project a couple of days ago.
This is a new and ingenious take on a perennial favourite; a method of monitoring the weight of a beehive and thus being able to judge the amount of stored honey (summer) or food supplies (winter), without having to open the top of the hive and pull out individual frames of comb to inspect them (which always disrupts the hive, no matter how careful the beekeeper is).
The problem initially looks easy to techies. Just pop a digital scale under the hive and automate sampling of the weight reading to have it delivered directly to your smart-phone. Unfortunately, if you’ve tried going down this route, you will have discovered for yourself that it’s not quite that simple. Digital scales (and load sensors in general) don’t deal well with being in a loaded condition for long periods of time (they tend to drift in a non-linear manner) and even if they did, there is still the problem of constantly supplying power to the scale at some remote (sometimes -very- remote) site. One of the other options is to use a mechanical scale and somehow collect the data (the common low-tech version of this has a cheap, mechanical bathroom scale in a wooden housing under the beehive with some sort of mirror arrangement to allow the beekeeper to monitor the weight on his visits to the apiary).
The OpenHiveScale project overcomes these problems by using a design based on the ancient “Steelyard” balance, with its sliding weight mechanism. The fulcrum is folded within the frame to provide a wide load capability in a compact package. The sliding counterbalance weight is driven by a stepper-motor and belt combination, with the “smarts” for the whole system provided by an ESP8266.
The whole of this project (electronics, PCB, mechanical build and firmware) are all available from the OpenHiveScale GitHub repository. Unfortunately, comments in the code are few and far between and there are no real build instructions on the site (there is an assembly_manual.pdf in the “mechanical” directory of the repository, but it is limited to diagrams, without any narrative), so you might have a difficult job duplicating their original work. The good news is that they do sell kits. The bad news is that they’re currently out of stock (and the price, including postage, is over €200).
The controller is modular, so if the hive is outside of WiFi coverage, an optional GSM, LoRa or SigFox card can be added (for an extra €30 to €40) to increase the range.
Power consumption is kept to a minimum by using an RTC chip to gate the enable signal on an LM3671 (low quiescent current) regulator and the recommended power source is a pack of 3 x AA alkaline batteries.
Unfortunately, the price (and lack of specific build details) make this a non-starter for all but the most well-heeled beekeepers, which is a shame. We can only hope that this unique design will become popular enough to make it into mass production (with, hopefully, a resulting drop in price). It’s easy to imagine other applications for this scale, too. Anyone who relies on tanked propane gas, for instance, would welcome the convenience of knowing just when the tanks need to be switched over (instead of having to go out at 10:30 at night, still wet and soapy from an interrupted shower).