Measuring the weight of a beehive

Is there any particular reason you bother yourself with power consumption as you can put a car battery with a solar panel charger to rid yourself of power consumption problems.? It's not like you'll leave your bees to themselves for two seasons? :)

Or am I missing something?

The two main reasons for the fiddling with the power consumption, is cost and flexibility. If this system turns out to work, I would like measure all our 200+ hives (my father works full time as a beekeeper). Therefor the cost of each weightscale is critical. Powering the each scale with 2 AAA batteries would be a lot cheaper then using a car battery and solar panel, even if I could power several scales from the same battery.

The second reason is flexibility. When the scale is completely wireless, everything can be hided under the hive with no wires lying everywhere to be tripped over. The hives are also moved a couple of times during the season (to get more honey), so rigging the system up and down have to be easy and fast.

A last benefit with my wireless modular system is that it is easy to add or remove modules from the network. The plan is to let the base station in every bee-farm auto detect the wireless scales without intervention from the user.

Lego-lars

Too bad you can't just use one of these:

http://www.flickr.com/photos/jtr27/8399594421/

(Or can you?)

Hi LEGO-lars Sorry about the delay of my answer(i was changing isp) What method did you follow to lower the power consumption? What chip did you use to amplify the signal from the loadcell? You say ''I plan to start up again this winter when I will have some more spare time. I notes that you are from Norway, I think you already have winter up there :P !! So please start again your project asap. Pictures and explanation...? of course there is interest !

On my side I have buy already tow arduino uno, tow loadcell 160kg, tow ina125, tow DS3231 rtc, tow DHT22/AM2302 Digital Temperature And Humidity Sensor, and i am waiting an Arduino GSM Shield (antenna connector). I plan to connect all these together and get daily reports of weight to my mobile. That will help me to know when the nectar flow stars or ends.

Power consumption can be done mainly by changing to an barebone Arduino setup, think the most cited article about this is http://gammon.com.au/power .

The initial outcome is that, to save power, forget about using a development board. Further savings (like reducing clock speed) would be overshadowed by the huge overhead of the voltage regulator and USB interface chip.

I think Lars used as OpAmp an INA333 as linked in an older posting above: http://bildr.no/view/1409684 and no additional ADC so there is really an option for better reading than 0.1 kg resolution.

I see this two options: Use an additional ADC plus OpAmp / PGA or a chip who has both integrated, see my posting under http://forum.arduino.cc/index.php?topic=198139.0 - so you see, you are not alone. :-) you may also have a look at the Seeeduino Stalker who has a lot of build in (charger circuit, RTC, SD) http://www.seeedstudio.com/wiki/Seeeduino_Stalker_v2.3

Hi again :) Here are some pictures of my project so far. This is the wireless sensor node. The Atmega328 is running at 1 Mhz internal ocilator. I am using a 32 khz clock-crystal connected to the xtal pins and timer 2, to make a the AVR work as a RTC. To amplify the loadcell I am using the ina333 op-amp and no additional ADC, but with some oversampling and black magic, I get something that looks like 12 bits of resolution :) As clements has pointed out, it is possible to use an external ADC, and probably get a better resolution. In my case I could not find anyone that works over the whole voltage span of two AAA batteries. A P-channel mosfet cuts the power to the loadcell and op-amp when they are not needed.

This is the prototype for the base station. It is using the sim900BE GPRS-module, and have interface for a DHT22 temperature/humidity sensor, and a rain gauge. It also have a solar charge controller.

This is a prototype of the actual scale that fits under the bee-hive. The plan here is to only measure one side of the hive and expect the other side to be equal. This would make the scale much easier to make, and I could use a smaller and cheaper loadcell. If this method is accurate enough, remains to be seen.

Just wondering how much the bees weigh and if there's times when they're all inside like at night.

A single bee has a weight of about 0.1 g. So a big hive has 3-4 kg bees. But most changing factor relating to weight is nectar flow and evaporation. Bees bring nectar to the hive with 80 % water. Honey has in the end under 20 % water. The difference must be reduced by the bees.

Hi Lego-Lars Have you got at suitable loadcell for you bi-hive weight ? I am very interested to here more about your project. Maybe we could help each other. I have acces to very cheap 120 kg full bridge single point loadcells In a month or so. Is I possible to here more about you have build your hardware, and maybe a little about your software. I am a be-keeper too, here in DK. Sorry for my English, it's a little rusty!

Hi Lars, there is a recommendation for an ADS1231 as ADC: 24bit and 128x PGA sounds good to improve accuracy a lot: http://forum.arduino.cc/index.php?topic=198139.0

I’ve seen a 12 bit ADC home game controller unit that’s already got instructions to use short shielded wires and needs care to not get garbage readings. What care must be taken past 16 bits? They aren’t snap-together Lego blocks.

Hi,
how Long stays the battery?
more than one month?

Best regards

Hello,

I am working on the same project! I started in July 2013 and at first, I used 4 load cells from cheap digital scale. I connect them together to form Wheatstone bridge, excitation voltage and amplification was done by INA125, analog-digital conversion with internal ADC in ATMega328P. For wireless communication, I used ZigBee at 2.4 GHz. My results were:

  • Do not use cheap 3-wire load cells. They drift with temperature and time. They lost precision. Creep is problem.
  • Do not use 2.4GHz if you need to communicate over 100 m. This frequency if full of Wifi/Bluetooth/noise. Everything from grass to trees will reflect your signal.
  • INA125 is good, but expensive.
  • 10bit ADC in ATMega is good, but not sufficient.

In my second version of electronics, I used 868MHz (yes, I'm from Europe) mesh modules from RadioCrafts (they call it TinyMesh). Maximum transmit power is 9dBm. I am testing them last few months and it looks very promising. I am able to communicate for distances over 150 m. Frequencies 868 or 433 MHz are much better in those projects.

The electronics is powered from 2AA batteries via step-up converter. With this, I'm getting quite stable 3 V. Also, I removed RTC and external crystal and for waking up MCU from power-down I'm using watchdog in interrupt mode. Thus, MCU will wake-up every 8s.

Instead of 4 small load cells, I used one 4-wire load cell (LEGO-lars used similar). This is my last problem with this project. The reading from ADC is not stable and it drifts with time. I put 2 kg on my 20kg load cell and after 2 weeks, the readings from ADC were lower then first day. Do you have similar experience with load cell?

Now, last month I am working on 3rd version of electronics. The digital part remains the same, but I completely redesigned analog part. I removed INA125 and used precision opamp MCP6V07. They have very low temperature drift and low noise. Instead of internal ADC inside of ATMega, I pick MCP3551 -- 22bit sigma-delta, low-speed 13sps. This new version of electronics will contain 2 opamp and 2 ADC, so I'll be able to measure 2 beehives with one electronics.


I am not fan of load cells. I would like to use multi-turn potentiometer. Unfortunately, I'm not mechanical engineer and don't know how to change weight into movement. It would be necessary to use some kind of lever and spring and gears to change small changes in spring into several turn of potentiometer shaft. Not sure if this is doable.

This is my second version of electronics.

Hi how Long will stay your battery?

From where did you come from (Europe)?

Question about battery life is quite difficult to answer. My first version of electronics used ZigBee and step-up converter to 5 V. I was able to run it with 2AA alkaline batteries for 16-20 days, measuring and sending data every 15 minutes.

My second electronics uses different radio and different step-up converter to 3 V. I didn't test this version for longer time than 6 days, but during this time I used fully charged new NiMH batteries and their voltage drop was 100 mV per 6 days, measuring every 5 minutes. So maybe 48-50 days with NiMH batteries? With alkaline batteries, those numbers would be different.

I'm from Czech Republic.

Hi Thank you.

I have build a scale with arduino and 3g shield. I us a Pb Akkumulator with 7,2Ah. In first time only 3 Weeks, the consumption of the systhem was 60 mA at 12V. Now the Systhem Needs 5 mA at sleeptime. I haven´t testet it yet but i think that 2 or 3 month are posible.

Best regards

I don't have experience with 3G shield for Arduino, but I think GSM modules can draw about 500 to 1000 mA during data transmission. Maybe you can save several measurements in memory and send them later at once. This can safe some power.

If your 3G shield has no sleep mode, try to use power MOSFET to turn it off. This can save a lot of power. ATMega328P in power-down mode draws max. 8 uA (@3V, watchdog enabled). INA125 (or other analog circuitry) can be disabled for most of the time. I think it should be possible to reduce power consumption at sleep mode below 0.5 mA.

Also, try not to use linear voltage regulator (ie. 7805), they are inefficient. Use step-down DC/DC converter (I suppose your accumulator gives 12V) to make 5 or 3 V. Their efficiency is 80 % and more. But remember, you have to choose step-down converter with at least 2A output current, because of your GSM module.

Hi,

yes, i have bought stepdown power suply, this will i test in next time, i turn the 3g modem off and i have disabled the led´s, so it does only Need less than o,1ma. I stop although the INA 125p. I think next week i will do the first test.

Now i know that i am on the right way.

I must only work on save data, at time i send every 1 hour one datapackage.

By .

Hello everyone, I am a commercial beekeeper from New Zealand. I am an amateur with electronics but would like to work on a project that is practical and that I can use. I can make the physical scales, but I do not know how to make the electronics or write the program. I know how to put electronic components together and can upload a program to an Arduino, can you help with the rest?

Trottel100 your project sounds most like what I would like - a scale that works remotely, I would like to use an Arduino with a GSM shield, this can make one weight recording at the end of each day and send once per day, even once every 2 days is fine. Our hives are a bit heavier, up to 200kg gross. I would like to be able to connect auxiliary hive scale to the master scale to get an average, ideally wireless but wired is not an issue. I would like a long term power source, solar or a 12v sealed acid battery or something along those lines.

If the forum can help suggesting parts, and if there is someone who could provide me the bare bones of the code and walk me through changes, or if there is code that exists I would really appreciate it. I am excited to try and learn something new.

Thanks!

Just a thought.

If you put the hive at one end of a lever on a pivot and the scale at the other then you could by making the lever arms uneven, use a scale rated for much less weight than the hive.

A very precise lever could be very short but practical I think may be 1/2 meter or longer to get 10:1. That way the tolerances of making the lever and positioning points can be cabinetry instead of space rocket.