#1 By: Ken Meyer, November 13th, 2013 16:38
I strongly recommend tracking hive weight if possible -- it's not easy and cheap(er) like tracking temperature at a couple points in the hive, but it's got significant applications for commercial beekeepers and researchers alike by showing when nectar is coming into the hive and giving a strong signal of how much food is stored and whether or not new supers may be needed.
I've been working on a hive scale and after an aborted installation last year, I have high hopes for a reasonably cheap ($100?) scale that can be plugged into a datalogger via a serial interface (or I2C or similar digital interface). I've got more details at http://hackerbee.com and I'd love to collaborate closely with anybody who can tolerate my slow pace of work (as a foster parent with a day job).
Another huge benefit to a hive scale is that the data (properly calibrated) can potentially be used in NASA's HoneyBee Net project that seeks to correlate nectar flow with satellite imagery of vegetation and land use changes to help us understand how climate change and land-use change is influencing plant interaction with insects.
More simply, temperature sensors are relatively easy to implement, and I've corresponded with a guy who has correlated certain temperature signals with the absence of a queen in a hive. Once temperature is being logged, it's easy to put in a few more sensors like humidity or even CO2. I've never seen anything useful come from a humidity sensor in a hive, but it's cheap enough that it shouldn't be neglected.
#2 By: Tristan Copley Smith, November 15th, 2013 08:28
Thanks @deamiter - we will definitely look into this and would love to collaborate. Please give us a little time to sponge up this info and we'll get back to you soon.
Fantastic work by the way!
#3 By: Bryan Hains, November 24th, 2013 16:33
Hi all, I'd recommend NOT reinventing the wheel but forking the hivetool.org scale instrumentation stuff. Free open source software for unix machines, uses off the shelf sensors (postal scale, temp and humidity probes) and either a cheap linux box (I use $75 lenovo laptops from eBay) or raspberry pi (that can run via solar, do wifi, etc). I've built two now for under $300 each and they're awesome --- I sample hive weight, internal broodnest temp, and ext temp, every 5 mins, and record sound samples every hour. The data are automatically archived and graphed, then made available on the web. Plus the data feeds to NASA's HBN. see hivetool.org and hivetool.net. It can all be set up in a day and works AWESOME.
Bryan (Landhaus H apiary)
#4 By: Tristan Copley Smith, November 24th, 2013 17:19
Hey @bryan - thanks so much for this, we hadn't found this project yet. Were looking into how this could integrate with our project.
#5 By: Ken Meyer, November 26th, 2013 12:47
@bryan that's great advice, and I actually spent last year modifying the same $150 scale they used! Unfortunately, there is a critical problem with the firmware in that scale in that it is a bit too power-hungry to run on batteries.
The Adams CPWPlus200 scale is designed to tare (zero) every time it is powered on, and while the unit I purchased had a bug in the firmware that caused it to not tare when the scale was loaded with at least 130 pounds, I confirmed with the manufacturer that this is not intended, and the bug may be fixed in future firmware revisions.
I do strongly advise simply reading data from a postal scale if you have reliable mains power to your bee hives, but at both locations where I keep bees, mains power is not an option.
I went on to purchase a number of other postal scales, and I concluded that anything cheaper than the $150 ADAMS postal scale is just too limited to hack into easily. I am confident that more expensive scales could meet our needs here in taking reliable data and then shutting down to conserve power, but I most beekeepers don't have a budget for that sort of thing.
In short, I don't believe that I'm reinventing the wheel here, I just don't have mains power near my bee hives, so I need to collect the data using low-power devices and transmit it to a remote database. Luckily both my sites are within radio range of mains and internet power, so I don't have to try to use cell networks!
#6 By: Tristan Copley Smith, November 27th, 2013 05:14
@bryan - do you have any contact info for the team at Hive Tool? I'm finding it very difficult to find any way of reaching out to them. Thanks!
#7 By: Joe Meyer, December 2nd, 2013 15:48
Check out this forum (you may have to register an account). I use to follow it, it was fairly active, and I think it still is. There is a section called "The Wired Hive Project" where they are trying to do very similar things as this project.
They kept a far more open mind than most other beekeeping forums I found.
#8 By: Lee Sutherland, December 12th, 2013 12:31
Scales can be made cheaply and easily by making your own load cell. Alternately, a load cell could be made available for far less than the ones being discussed here and elsewhere. The reason? No fancy interface...a smart system already has the processor and it can do whatever it wants with the voltage output. I'd recommend designing in the resistor bridges to the hardware platform.
The ones I've used for commercial products come from Vishay. The fabrication of accurate units requires care, but is not difficult. Putting an inexpensive bridge (low precision resistors) on the board is possible because it already has a temp sensor as well, and a simple deconvolution is possible to effect a thermal compensation for the load cell after it has been installed (using the processor again).
#9 By: Joe Meyer, December 12th, 2013 12:48
Load cells measure something occasionally and are allowed to spring back to neutral. It's my understanding that accuracy diminishes when a scale is constantly measuring a slowly increasing load. Maybe the first phase focuses on trending data rather then accurate measurements?
#10 By: Lee Sutherland, December 12th, 2013 15:51
The creep coefficents for even cheap strain gauges are significant but small for small strains. The time constant can be on the order of days for ppm-level strains, and this is why I mentioned that these gauges can be uses to make accurate relative measurements. In short, you can't know exactly what the strain state is after a period of time...but given 1) a series of measurements over time, 2) an initial calibration (not absolute) to establish a load line (in kg mass/mV, for example), and temperature compensation data (resistor drift, creep, and CTE mismatch), and integrating the changes, one can make very good guesses about changes in mass from day to day. What matters is not the long-term creep trends, but the day-to-day or hour-to hour changes in the mass of the hive.
TL;DR: Creep is slow. UNder the right circumstances, you can use a data history to make the direct measurements irrelevant and use short term measurements and characterization instead, especially where cyclical trends are present.
If this approach could give a confidence interval of 50% for +/-10% of the weight, and if it costed $10-$15 instead of $$$$$, it might be a more appropriate choice for wider distribution.
#11 By: Nuf4n , December 16th, 2013 01:55
I made a scale a few years back and gathered about a year's data from it.. 1 minute polls.
I've put this off for a while, but here's all the details! Summary: I made (and you probably can too!) a scale that is readable via USB with better than 1lb resolution for less than $50. I have bee...
I had been working on a solar+battery+jeenode (wireless) version, which incorporates a 1wire bus, and therefore can do temperature, humidity, whatever.
Development has stopped for the moment though - I'm taking some time away from beekeeping. I may start up again in 2015.
#12 By: Lee Sutherland, December 16th, 2013 12:08
Perfect! I might do this too...
#13 By: Jeff Thomas, January 10th, 2014 14:31
@trizcs I have been working with Paul at Hive Tool over the last few months. Let me know if you still have a need to discuss anything. I just ordered supplies for the scale and hope to connect to a RasberryPI.
#14 By: Colten Jackson, January 20th, 2014 01:40
I've got supplies in the mail and I'm hoping to equip a networked raspberry pi with temp, scale, and vibration sensors using force resistors (like this one http://www.adafruit.com/products/166) and piezo sensors, like the kind used for contact microphones. I think I should be able to keep the cost around $50-75 (including the raspberry pi...an extra $40 for solar power).
I will post my progress here and hope to hear from others who are already doing monitoring. @lee, could you link to any websites currently monitoring beehives? I'd love to get a look at what other people are doing.
#15 By: Jeff Thomas, January 21st, 2014 21:45
@lee check out the hives at http://hivetool.net/.
#16 By: Ken Meyer, January 29th, 2014 20:14
@eojreyem the constant load will reduce the accuracy, but the drift due to constant load should settle over many days. The calibration won't stay accurate for years on end with rather large temperature swings and a varying load, but since the load will only change very slowly (perhaps 2 pounds per day out of a 400 pound full scale) and the load will never be fully removed (except perhaps a couple times a year in a full-hive inspection) I hope this is not a major effect.
It will certainly be important to check the calibration of the scale regularly (probably 2-3 times per year) but load cells will not deteriorate forever under load. As Lee said, because we are primarily concerned with when nectar is being collected or consumed from one day to the next, I suspect (and hope) that long-term drift will be largely negligible.
As a further note on lower-cost load cells, I purchased 10x 200kg load cells on aliexpress.com: http://www.aliexpress.com/store/product/Free-shipping-30-pieces-lot-Single-point-parallel-beam-aluminum-Load-Cell/712946_587055121.html
They cost about $35 each (shipped from China) and I was impressed with the build quality, and they roughly seem to match their specs (I haven't tested carefully yet).
There is some significant risk in purchasing from Aliexpress, but I am happy with the units I received. I would be willing to sell some of them to anyone interested for $35 plus shipping (probably only worth it in North America). Also note that while the minimum quantity is listed as 10x, I believe the sellers are very open to selling smaller quantities upon request.
#17 By: Colten Jackson, February 24th, 2014 15:33
@deamiter I'll probably be interested in buying a scale from you. A friend and I have an idea to automate the measuring process by way of an electronic mechanism that lifts and lowers the whole stack of hives just a fraction of an inch, thereby allowing the scale to be zero'd before every measurement.
I'm going to see how realistic it would be to hack bathroom scales for this purpose, but $35 is a good deal!
#18 By: Christopher Borke, February 25th, 2014 01:27
I think that the pressure sensor/weight sensor is a great idea and has been fairly hashed out and I'd like to throw another contender in the mix.
Relative humidity sensor
Fromm Varroa Mite Reproductive Biology by, Zachary Huang:
When relative humidity (RH) was set at 59–68%, on average, 53% of the mites produced offspring (N=174 mites); under 79–85% RH, only 2% (N = 127) of the mites reproduced.
I've had a few ideas integrating a humidifier as well. I think it may be possible to design a heating element with a water drip feed to artificially raise the humidity of the hive (not in the winter of course). Think a tobacco/marijuana vaporizer pen element calibrated exclusively for water.
#19 By: Colten Jackson, March 1st, 2014 20:46
Relative Humidity is often packaged alongside a temperature sensor, and they run about $10. It's a good choice to start with. As for artificially raising humidity, the folks that grow mushrooms got that figured out: you use an ultrasonic jewelry cleaner ($20-$30) to shake water into the air. There are other 'ultrasonic humidifiers' that cost more and are meant for whole rooms. The smaller jewelry cleaners are better for containers and do the same thing. Hadn't tried it myself, but I'm going to try to keep some pitcher plants and venus's fly traps alive and will be experimenting with that kind of set up. You could also just set some wicks or cardboard in water to use capillary action and evaporation to up the humidity. A fan blowing through corrugated cardboard (the open spaces) sat in a water reservoir will do the trick. Very good tip about the mites.
Here's a sensor no one's mentioned: dust! Here's a blog a friend of mine wrote up on his project, dustduino.
The short of it is that you can measure particulate matter in the air with a diameter between 1 and 10 micrometers with a sensor that costs about $15. Sharp GP2Y1010AU0F is the name of the sensor. I'll be deploying these and I'm very interested in how well they sense the drift of pesticides and talc coming off of the fields as the corn gets planted.
#20 By: Glen, March 15th, 2014 16:08
I just finished playing around with a bathroom scale and currently have it calibrated and connected to an Arduino reading data. The scale costs a little over $20, and the entire project can be completed in a few hours for about $25. I think this could be a great way to go about getting the weight of a hive and it should be pretty accurate.
I have uploaded instructions and Arduino code here. Let me know if anyone has suggestions or other ideas.
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