Measuring the weight of a beehive

Yes, I will publish code and constructions files. I am in a beta / alpha phase so not all is perfect, e.g. I have an design error in the PCB file, so I have to connect two pins to the Stalker directly and not over the shield. But one prototype with 2 DHT22 or 33 sensors, 5 DS18B20 and load cell is sending data every 20 minutes since over four weeks without any problem from my balcony. We set up an other installation some days ago with reduced sensors--only humidity/temperature outside and the weight--and this is running also.

You can find the graph of a test installation under
http://open-hive.org/prototype-bee-scale/prototype-brandenburg.html

It is an interactive graph. You can select an area with the mouse--the timeline or the value range--so you can zoom in. With a double click you got back to all datapoints: Under the graph there are check boxes for every data series. If one chosen, for example only the weight and all other off, the script scales automatically the graphic so that the current values are populate the full scale range.

I use dygraphs http://dygraphs.com for visualization, a JavaScript library that deals with many data points. It runs as browser side JS, not on the server Thus, the first call may take more time when thousands records are loaded but if you then zoom in or out is the super fast.

The raw data, which the script directly processes, are simple comma-delimited values on the server:

Date/Time,Weight,Outside Temperature,Outside Humidity,Voltage
2016/06/15 20:34:38,  71.892, 17.3, 99.9, 4.08
2016/06/15 21:34:38,  71.810, 17.2, 99.9, 4.07
2016/06/15 22:34:38,  71.692, 16.3, 99.9, 4.07
2016/06/15 23:34:38,  71.614, 16.0, 99.9, 4.07
2016/06/16 01:34:38,  71.525, 15.4, 99.9, 4.06
2016/06/16 02:34:38,  71.470, 15.0, 99.9, 4.06
2016/06/16 03:34:38,  71.405, 14.0, 99.9, 4.06
2016/06/16 04:34:38,  71.363, 13.5, 99.9, 4.06
2016/06/16 05:34:38,  71.329, 13.3, 99.9, 4.05
2016/06/16 06:34:38,  71.378, 14.6, 99.9, 4.06
2016/06/16 07:34:38,  71.439, 22.0, 78.6, 4.08
2016/06/16 08:34:38,  71.496, 21.6, 71.1, 4.11
2016/06/16 09:34:38,  71.339, 21.9, 76.0, 4.14
2016/06/16 10:34:38,  71.216, 21.4, 73.9, 4.17
2016/06/16 11:34:38,  71.252, 22.0, 75.0, 4.18
2016/06/16 12:34:38,  71.245, 22.5, 64.6, 4.18

You can see on the first photo the complete bee monitoring system:

  • The main electronics in the middle.
  • Right in blue, a drilled cup with a DHT33 / combined humidity/temperature sensor for outdoors.
  • Below are the load cell for a unilateral weight with aluminum L-profiles.
  • On top 5 DS18B20 temperature sensors (can be more also) for the brood nest area.
  • Left side in curlers (against cementing) a DHT33 for indoor use.

All sensors are connected with round cables, which can be good passed through the screwable, waterproof cable glands on the case. An exception is the temperature array for inside (on top of the photo). There is a small board as flat cable connector. With this flat cable it is very easy to connect a pin header as as branch for the various temperature sensors between the combs.

The electronic case with a small solar cell under the transparent acrylic cover. The box is waterproof. The screws started after a wet day to rust. The box in the photo is on the balcony for about a month.

Inside the box it's quite busy:

  • At the bottom you can see the Seeeduino Stalker (red board), an Arduino derivative with additional clock (RTC), a charging circuit for solar panel and Lipo and a bee socket. "Bee socket" has nothing to do with bees ... haha! On the bee socket, the GSM / GPRS module sits, with "SIM800" print.
  • Right (white) is the self-designed shield with the load cells IC, some screw terminals, resistors, caps. Currently we have connections for a load cell and up to 3 DHTxx or DS18B20 sensors.
  • The small printed antenna for the modem is between board and housing, a black cable goes (almost invisible in the pic) from the modem to the antenna
  • The rechargeable battery, a Lipo, is under the Stalker and and so not visible.

Soem close ups Lipo, printed antenna, DHT on a smal breakout so that it fits in a curler, same DHT covered by a drilled Ikea cup for weather protection: