[neilh20]

@khaase  interesting getting the LiSOCL2  activated.

My 2Cents is it would be good to characterize the 350mA  pulse – and isolate it from the mega1284’s  high impedance LiSOCL2.   That could mean that for the “high impedance” (for a battery)  LiSOCL2,   the current draw has to be kept below a threshold, treated as a constant current source.

Then the issue is also how to detect when the LiSOCL2 is running out of energy, and can’t take more high current pulses, can it gracefully manage the power situation.  Unfortunately its not a trivial problem.

 

[neilh20]

Mostly the cables we put in are armored –  3/4″ flexible and can be joined easly – something like https://www.lowes.com/pd/HydroMaxx-3-4-in-x-50-ft-Black-Flexible-PVC-Pipe/1002884464

Also seen cables chewed by squirrels .

[neilh20]

Hi @khaase I haven’t figured out what the source of the reset is, as the AVR1284 Arduino code discards it – very frustrating.

I have used low ESR capacitors – something like Digikey 732-9079-1-ND CAP ALUM 680UF 20% 10V THRU HOLE LOW ESR

Whenever I have longer wires, a power switch, or current measurement, with the LiIon battery, I get some resets. I’ve also standardized on using 4400mAh LiIon battery.

My EC circuit has low dynamic power demand.  Are you looking to add larger dynamic power demand with radios?  The LiSoCL2  has a relative high impedance,

Managing power demand is challenging, not taking too much power when its not available. Using Vbat to estimate power is tricky. Vbat measurement is noisy and is referenced to the Vcc, and is only theoretically  accurate when Vcc=3.3V . So the LiSoCl2 3.6V is pretty close to the design limits of the regulators (though far improved than the Mayfly 0.5 regulators)

[neilh20]

Maybe of interest https://www.envirodiy.org/topic/primary-powering-in-cold-settings/

[neilh20]

@davem great topic.  I was at a SSU Eng Presentation yesterday by Enphase   a leading solar equipment provider and they use LiPo4 in their battery 3.3Kwh/10Kwh systems.  All about safety.  LiPo4 slightly less power density — but that isn’t a problem with stationary systems.  No temperature stability. Fire issues are a big deal. A recent newspaper report on a local house fire referenced a device that had been left on charge and caught fire.

I’ve got some largish PO4 tube batteries designed for electric bikes.  However the challenge is as you point out is different charging regime and management.  At the present my guess it can be a system block at 5V or 12V.  However it would be nice for SBC (single board computers) like the Mayfly to have the LiPO4 interface.   I seemdd to remember Rocket used to with SAMD21 LoRa + LiPO4

There was also a rPi powering system that used LiP04 – I think this is,

https://hackaday.io/project/13260-lifepo4weredsolar1

One way of minimizing power consumption with fast sampling is to queue the reading,  and then upload every 4-12hours, which is what I do, but is a lot of software work. When I have some time I plan to post it for the Mayfly, but haven’t heard a lot of people asking for it.

Also to minimize cellular power, use a cloud host that can encode the data and suck the data up fast. However subscriptions are quite costly. So great topic 🙂

[neilh20]

Hello Dave, thanks for sharing.

I had thought of getting the device, because of the price, so interesting.

The issues I saw is that it has two sources of analog error and unquantified temperature coeffocient  for each source of error.

Every “analog” device typically has a temperature dependency, This would be the depth sensor itself, which will vary the reported depth based on the varying temperature of the water. Typically small if the temperature is stable as in  underground water measurement.

The second analog error  – which is the current transformed to the voltage. This resistance will vary based on the air temperature.  Resistor need to be selected and stated for the their temperature variation. There are resistors that have a low temperature coefficient. So the device from Seeed should state what its temperature coefficient is, but I couldn’t find it.

So just an observation, and thanks again for sharing.

 

[neilh20]

Hi James, if you have the spare jumper cable sockets you could try it and it probably will work.

The challenge is the Mayfly doesn’t have a lot of capacitive buffering and the LiIon battery performs that function.  It might be more reliable to have a battery on each Mayfly and run the solar panel to both.  Of course the boards need to be kept physically isolated so they don’t connect electrically.

My  node is using a LT500/SDI-12 and a Keller Acculevel/Modbus on Mayfly 0.5B https://monitormywatershed.org/sites/TUCA-Na13/

Its using a release based on 0.28.5 ~ https://github.com/neilh10/ModularSensors/releases/tag/v0.28.5.release1_210711  and it is built as a working release in https://github.com/neilh10/ModularSensors/tree/v0.28.5.release1_210711/examples/tu_xx01 with src/ms_cfg.h_LT5KA_lte copied to ms_cfg.h

 

[neilh20]

Wow thanks so much for sharing, and no problem with your English.  I’ve been in that situation where its difficult to debug ModularSensors/Mayfly as the software implementation using time loops is so time sensitive.

Are you planning on using a git to store the programs with an open source license? Its very nice if you do and gives some confidence in being able to do crowd sourced testing and feeding back how it works.  🙂

Just wondering if you are using your program with the Mayfly implementation?

One issue to keep in mind if using the Mayfly, is that the SDI-12 is specified electrically as 0V to +5V, and the Mayfly as SDI-12 recorder/host/server implementation has a reduced electrical interface to only do 0V to +3.3V. This makes it easy to implement.  However it can mean that the SDI-12 sensor equipment doesn’t detect the incoming packet. I’ve seen this for the Insitu LT500 equipment   ~ or at least I got a non-response from some older equipment and assumed that was the reason. Similarly with the Vegetronix SDI-12 analog sensor that has been tested to the SDI-12 specification, it doesn’t respond. An earlier version of the Vegetronix SDI-12 analog sensor does respond, but that version didn’t have the CRC implementation.

You solve the electrical interface by using the TekBox TBS03 (or at least hopefully it covers it), though I wonder if it also reports packets that are out of electrical specification?

[neilh20]

@rogers1313 – its a good “engineering question”. speaking as an electrical engineer and some one that has blogged on understanding traceability,  measurement range, measurement resolution. measurement accuracy and  total error band of measurement being different aspects of the  measurement.

In short the Hydro 21 has calibrated measurements that can be read digitally (SDI-12) with defined accuracy.

Data sheet for Hydros 21 https://library.metergroup.com/Integrator%20Guide/18468%20HYDROS%2021%20Gen2%20Integrator%20Guide.pdf

A more complex answer on accuracy is what are you trying to measure accurately?

See Hydros 21 CTD  ” 3.1 specifications”  and I queried  the manufacturer about some aspects of the specifications (and afterwards the specifications where updated and easier to understand). The nice part of the Hydros 21 CTD is the “low cost”, SDI-12 interface, combined  Depth, Temperature and ElectricalConductivity in one physical unit.

Water Depth units are mm an accuracy is ±0.05% of full scale at 20 °C, for full scale of 10,000mm that is +/-5mm @ 20C

However there is the real world “NOTE: Depth measurement accuracy assumes no abrupt temperature variations.”

No abrupt temperature variations is not defined  – and I asked them about it – is that a 1C shift in 15minute period, or 10C shift in 15minute period. If you are measuring the last 100mm of a stream drying out in a mountain pool, with say a 10C temperature diurnal change then there may be a temperature dependency on the measurement. If you are measuring the way a water body peaks at 10m (33ft), from 1m(3ft) or well water depth changes its probably good accuracy.  The engineering challenge for this type of water depth sensor is that the pressure sensor that converts  water depth to an electrical parameter is  highly optimized resistor, which has a large temperature coefficient. Generally speaking for accuracy in the component sensor, its usually stated as between 10% and 90% of range – but this is complicated engineering. Sufficient to say again, if you want to measure the last 100mm of a stream drying out which we do in California accuracy is challenging.

Temperature is one of simples aspects of measurement and reasonable accuracy at +/1C and resolution at +/0.1C. Units are C

EC is stated as accuracy  ±0.01 dS/m or ±10%, whichever is greater, Resolution 0.001 dS/m

There are some users on this board who have extensive experience with CTD21, however the people I work with in drought areas with large temperature changes don’t use it, and I’ve only looked at the specs, never tested a unit.

When it comes to sensors I have tested for accuracy and temperature dependency a number of low cost sensors, and also Keller Levelgage (lousy temperature dependency)  Keller Acculevel (better ) and the gold standard that TU Oakland uses Insitu LT500. I’ve also returned some LT500 to the manufacturer for further calibration of the temperature coefficient as it was outside their stated range.

https://www.envirodiy.org/comparison-temperature-dependency-in-situ-lt500-and-keller-nano-level/

https://www.envirodiy.org/measuring-low-water-in-streams-accurately/

The LT500 has the ability to define the units, as well as few other parameters.

Hope that is useful – BTW I’ve also started a thread on using Scaling Modular Sensors https://www.envirodiy.org/topic/geographically-scaling-modular-sensors/

[neilh20]

(edit : thanks Heather this is post had got stuck) @rogers1313 great to hear your project (from your posts in the https://www.envirodiy.org/topic/mayfly-v1-1-technical-questions-forum-thread/#post-17333)

– thanks for filing your profile https://www.envirodiy.org/members/rogers1313/profile/

I’m similar EE/and FirmWare – https://www.envirodiy.org/members/neilh20/profile/ – youre welcome to email me dreictly, but this is also a good place for discussing how to deploy.
Matt is also deploying for TU https://www.envirodiy.org/members/mbarney/profile/
This thread may be of interest – I’m targeting my fork for easy deployment and reliable delivery of readings .

I’m scaling some systems for Tu N California, and documenting some of it through this (but an open source wip).
https://github.com/neilh10/ModularSensors/wiki

https://github.com/neilh10/ms_releases
https://github.com/neilh10/ms_releases/wiki
https://github.com/neilh10/ms_hardware

For low cell phone service I’m using an android app “Phone Signal” https://inpocketsoftware.com/phone-signal-cell-strength-overview/ for doing a survey.
A note, IMHO the core https://github.com/EnviroDIY/ModularSensors works for where there is reliable phone service – excluding some 90% of potential coverage range where the cell signal may be marginal.

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