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@shicks
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The shield wire of the OBS3 sensor cable doesn’t actually connect to anything on the sensor, so it’s okay to leave that floating, especially if you’re just testing the sensor. The green and black wires both definitely need to be connected to GND or the sensor won’t work properly. Both the high range and low range should read around 0 NTU when the sensor is in air (assuming the sensor is clean and not pointing at any objects). You should also not test it near sunlight (out of the water) because the light from the sun will interfere with the sensor’s IR input and you’ll get extremely inaccurate results. Placing a dark object like a towel or a boot or a glove over the sensor will give inconsistent results since the IR reflectivity of different color objects will give different readings. We found that using a piece of white paper or a bare hand about an inch away from the sensor is a good way to see if you get full-scale readings from the two sensor outputs. Using a voltmeter, you should see around 2.5v for both sensor output wires when you do this. With nothing near the sensor, you should see very close to 0v on both channels. (Be sure to check that you’re getting 5v from the Mayfly on the V+ line of the screw terminal too).
It’s possible to use a battery that big, as long as the polarization of the JST connector is the same. However, we rarely have the need for a large battery with our standard stations with sensors like CTD, turbidity, or oxygen, even with cellular telemetry ever 5 minutes. If you use a really large battery, you have to make sure your solar panel is appropriately sized to fully charge the battery on most sunny days. If your sensors are drawing a lot of power and your solar panel is undersized (or in a lot of shade), then you might have trouble fully charging a giant battery every day and you’ll end up with a dead battery after awhile. If you have a really power-hungry sensor or accessory that draws high amounts of current, it is usually a 12-volt sensor or motor or pump, so it would make more sense to use a 12v battery in your enclosure, along with a 12v solar panel and a separate 12v charger for whatever type of battery chemistry your 12v battery is. The Mayfly logger boards were designed to run on 3.7v lipo batteries, and there are boost converter that generate the switched 5v and 12v supplies for external sensors. The latest Mayfly v1.1 boards use power directly from the solar panel input connector to power the logger and boost converters, and will only draw power from the battery if there’s not sufficient power from the solar panel. This means that on sunny days, many stations with simple sensors and a cell board can operate totally from sunlight for a large part of the day, and only draw power from the battery at night, or when it’s cloudy. This is an improvement over previous Mayfly designs from earlier models where all power is supplied from the battery at all times and it only charges when there’s sufficient light. This means that stations are more efficient with how they use power. We also started using the ETFE solar panels a few years ago that offer 5watts out output power, instead of the 3.5watts the older style panels produced with the same size. So for most people, the new panels coupled with the newest version of the Mayfly board result in sufficient charging and power supply for most deployment configurations.
Those old Campbell OBS3+ turbidity sensors will either flatline or go negative when they fail. We started deploying dozens of that sensor model about 8 or 9 years ago and almost all of them have been removed from the field in the past few years due to failure. It looks like your station is 8 years old so you got more life out of it than most. To double-check that the sensor really is bad, you can put the Mayfly logger into continuous testing mode by pressing the D21 button, so that the sensors stay powered continuously for a few minutes. Use a voltmeter to check the 5v output supply voltage of the Mayfly board, using the Vcc and Gnd pins of the screw terminal board that the turbidity sensor is connected to. You should see around 5v when the sensor is being powered. If not, your Mayfly board isn’t generating the 5v signal to power the sensor, or the sensor is drawing too much power (usually due to flooding of the sensor housing) so it is shorting out and causing a voltage sag on the supply. You can also check the signal output voltage of the sensor by looking at the two sensor signal wires on the screw terminal board (test them individually, so measure across S1 and Gnd, then S2 and Gnd.) Because I built and installed that particular station you’re referring to, I still have the voltage-to-NTU conversion calibration sheet from the manufacturer so I can send you the equations the logger uses to convert the raw analog voltage readings to NTU. If you manually calculate the turbidity different than what the Mayfly is calculating, then it could possibly be the analog-to-digital converted on your logger board has gone bad, but this is rare. It’s more likely that the sensor has simply died, but since Campbell doesn’t repair these anymore, you only option would be to replace it with something like the newer ClariVue turbidity sensor.
We’re really excited to partner with Labcrafter so they can be a source of our products to people in Europe. As for sensors, the Maxbotix MB7389 you mentioned is probably your best bet for low cost ultrasonic rangefinding. Just be sure to order the TTL version so it’ll work straight into the Mayfly board (the RS232 sensor would require an interface chip). I haven’t used the Atlas Scientific pH sensors so I don’t have any advice on them.
All Mayfly logger board from version 0.3 to the current v1.1 (and including your v0.5v) have a separate 3.3v regulator that powers external sensors, and also the 5v boost circuit. This secondary 3.3v regulator is turned on or off by controlling pin D22. When the regulator is turned on, a red LED in the lower left corner of the Mayfly should turn on. There’s a possibility that perhaps the sensor died and damaged the 3v (or 5v) output circuitry on your Mayfly. Do you see the red LED (labeled LED3 on the Mayfly v0.5b) turning on during samples? Have you tried putting a voltmeter across the ground (GND) and V pins of the SDI12 grove jack during readings to see what voltage you’re sending to the sensor? You can set the voltage selection jumpers to either 3.3v or 5v for the Hydros21 sensor, it should work with either.
How old is the sketch that you’re using on the v0.5b board? If your old board was programmed before May 2022, then the old code won’t work with the newer Gen2 Hydros21 sensors because the SDI12 library for communication with the library had to be adjusted for some slight timing changes in how the Mayfly communicates with the sensors. Your v1.1 board is newer and probably has the updated SDI12 library and therefore is able to successfully talk to the sensor.
If you are physically relocating a monitoring station that reports to MonitorMyWatershed (MMW) then it’s best to create a new site instance on MMW for the new station. That way all the old data that was collected at the original location will still show up on the map at the original location. If you edit the MMW location for an existing site, the the marker on the map will move to the new site, but all the historic data will be associated with the new location, which is probably not what you want. So it’s best to think about relocating a site the same as you would for creating a brand new site with new hardware. The Monitoring Station Manual on our website walks you through the whole process of registering a site on MMW and programming your Mayfly board. You’ll get new UUIDs from MMW to paste into the Arduino sketch that you’ll program onto the Mayfly boards to bring them up to date. You will also need to activate your cellular SIM card and install them into the logger’s cell module after you’ve updated your Mayfly with the new logging sketch.
If a Mayfly board has been in storage awhile or with a dead main Lipo battery, the onboard coin cell battery will likely be dead and you’ll need to replace it in order for the RealTimeClock (RTC) to retain the date/time whenever the main battery is disconnected. The current Mayfly boards use CR1220 3v batteries, which can be ordered online or found at most pharmacies. Be sure to insert it into the battery holder on the Mayfly board properly because inserting it upside-down will permanently damage the clock module. There’s instructions and photos in the Manual about how to properly install the battery. Once you’ve got a good battery in the socket and you power up the logger with cell module (with antenna) with a SIM card with an active cell plan and adequate cell reception, the board will attempt to connect to the online time server and set the RTC. Sometimes when you’re using a brand new, freshly activated SIM card, it can take several minutes or several tries (of cycling the power after 2 minutes and trying again) for the cell network to recognize the new card and give the board a connection. So that’s why in the manual it mentions watching the Mayfly’s serial output on the IDE’s Serial Monitor to keep an eye on the status.
It would also help to know what hardware versions of the Mayfly and cell module you have. We’ve released 7 versions of Mayfly boards over the past decade and several different cell modules, so the Arduino sketch you upload to the board is extremely dependent on which version of the hardware you’re using. The latest Mayfly version is v1.1 and the latest cell board is the EnviroDIY LTEbee (https://www.envirodiy.org/product/envirodiy-lte-bee/).
I personally haven’t used any Sandisk Ultras with our loggers, so I can’t say how it performs. This guy did a really great test last year with a variety of microSD cards and summarized his findings (particularly on idle current) in a really helpful list: https://neurotechhub.wustl.edu/micro-sd-card-low-power-showdown-part-ii/
Genuine Sandisk and Kingston cards have served us well, not drawing excessive power when the board is sleeping, and being reliable over many years in field deployments. What we’ve seen issues with is generic cards from random manufacturers because they either fail and corrupt the data after a short time, or they draw 5 or 10 times more power than other cards. I think any high-quality brand that’s 32GB or smaller should work fine, but you might want to keep an eye on your battery voltage for the first few days after you switch to a new card to see if your battery voltage levels perform the same.
If you’re having trouble getting all the libraries to work happily together, you could try downloading all of the ModularSensors dependency libraries from the release files on github:https://github.com/EnviroDIY/ModularSensors/releases
You can scroll down that page and find the zip file at the bottom of each release summary (under the “Assets” heading”). So if you try the latest release and have issues, you could back up and try an earlier release.
We haven’t deployed any ClariVue10 sensors lately, it looks like the last time I did, it was using ModularSensors version 0.34.0 and we didn’t have any issues at that time with the code. We haven’t bought any of those sensors in the past few years to test the code with them, so it’s possible there have been changes to the sensor design or firmware that would require some updates to our Arduino library.
Are the 3 solder jumpers on the back of your 6-pin screw terminal board soldered properly? We noticed a few of them came from the factory with no solder on them, so I soldered them in the “Default” position before shipping them out, but there’s a chance yours might have been missed. You can also try closing solder jumper SJ25 on the back of the Mayfly board to change the 12v boost converter to 9v output instead. We found a few ClariVue sensors that apparently needed a little more power during the initial startup than the 12v boost converter can provide, and by setting it down to 9v that’ll send a little more current to the sensor and seems to give us better reliability.
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