My take on measuring how much water remains in the tank

[TheArgobus]

I have a forty gallon fresh water tank, but it came as just a rectangular tube with no ports or anything. Just a piece of plastic. I wanted a good way to figure out the water level in the tank, but most solutions used a "liquid level sensor" that would only tell you if there's fluid at a specific level (like 1/2 full), which wasn't good enough for me.


Knowing this ahead of time, I put a paddlewheel style liquid flow meter in the PEX plumbing coming out of the tank, in anticipation of figuring out how to utilize it later. Well, here I am a year later, and I finally got it working!


It uses an Arduino, a display, and an arcade style button, along with a few other goodies to make it nice and fancy. It's powered by the water pump circuit, and measures how much water leaves the tank. It simply subtracts that quantity from the total tank capacity, and voila--now I know exactly how many gallons of water remain in the tanks.




(the decimal light doesn't work, so I know this says: 33.7 Gallons remaining)


I also installed a liquid level sensor in the vent line from the tank, so that when water starts rising through the vent line (i.e. the tank is full), an indicator LED turns on at the fill port so I don't have to spill water out.






It saves the gallons_remaining variable to the onboard memory, so it carries it over even if I turn the water pump off, and I calibrated/tested it to within .1 gallons accuracy. It also tells me how full the tanks are as a percent, and the current flow rate (in gallons per minute). All I have to do is fill up the tanks to max capacity, turn the water pump on (and top off the tanks), and then hold the button for 2.5 seconds and it'll register that the tanks are now full (a full 36.0 gallons).









It definitely isn't an industrial solution, but it totally works for my purposes! And it also was a way to pass time during this quarantine.


I made a post about it on my build thread here (https://www.skoolie.net/forums/f27/t...tml#post383445) but due to character limitations, I couldn't post the code on skoolie.net--the code, commentary, and (Amazon Affiliate) links to the specific items I used are on my build blog here (https://theargobus.blogspot.com/2020...flow-rate.html).



I also had a battery powered clock attached to it, so I could calculate my water usage per day and see how many days I have left at my current usage, but that ended up being too complicated and I decided to keep it stupid simple.


I have two other Arduino gadgets that I think are pretty clever, one is an automatic fan turn on circuit for my electrical compartment (if it gets too warm in there) and the other is a "dash helper" that uses GPS and another Arcade style button to give me speed, percent fuel tank full, distance to go till empty, and an automatic 5 minute shutdown timer. The write up on those are coming soon.

[Drew Bru]

Dude, that is slick as hell. I'm jealous of your talents and ingenuity!

[kazetsukai]

Originally Posted by TheArgobus

I also installed a liquid level sensor in the vent line from the tank, so that when water starts rising through the vent line (i.e. the tank is full), an indicator LED turns on at the fill port so I don't have to spill water out.

I hate my fill port! I think these things are so clumsy, and it leaks inside the wall. I'm looking for replacements.

Originally Posted by TheArgobus

I made a post about it on my build thread here (https://www.skoolie.net/forums/f27/t...tml#post383445) but due to character limitations, I couldn't post the code on skoolie.net--the code, commentary, and (Amazon Affiliate) links to the specific items I used are on my build blog here (https://theargobus.blogspot.com/2020...flow-rate.html).

If you plan on doing various code projects you'd like to share, use GitHub and link to there. Automation has been a key feature of my build and I put all of my code there.

Nice work.

[TheArgobus]

kazetsukai, I've been following your build and your set up is truly a work of fine art! It's definitely inspired me to think of other things I could do, but I I'm out of ideas!


As for this contraption, I realized today on a day trip that I should've oriented it around "gallons used" instead of "gallons remaining". That way, I could just track how many gallons I've used in case I filled it more or less than 36 gallons, which would happen on any surface other than level.

[Danjo]

That’s better than tank sensors because you’re rarely
Level enough.

[TheArgobus]

I created a GitHub account for this and my future arduino/raspberry pi gadgets.


https://github.com/TheArgobus/Tank-Level

[Native]

Excellent! Thank you for sharing your design experiences here and on github.

[kazetsukai]

Originally Posted by TheArgobus

https://github.com/TheArgobus/Tank-Level

QQ: Looking at the EEPROM writes: Does the board lose power often?

You have a lot of if blocks with one,two,three,four and references to data[index], probably could separate these into functions. Same with the hack variable checks. It would result in less groups of code that look nearly the same.

To demonstrate, on my sketch If you look at Line 258:
https://github.com/kazetsukaimiko/au...nlink.ino#L258

You can see the boolean function:

// Is the pinNum a valid digital pin?
boolean validDigitalPin(int pinNum) {
  return ((pinNum >= 0) && (pinNum < NUM_DIGITAL_PINS) && !bannedDigitalPin(pinNum));
}

You could do something similar:

// General function to compare hack variablees
boolean hackCompare(long compareTo, long delay) {
  return (hack - compareTo) >= delay;
}


// Was the last button press longer than delay (1000, 1500, whatever you pass in)
boolean lastButtonDelay(long delay) {
  return hackCompare(hack_button, delay);
}


// Your old if block:
if (hack - hack_button > 2500) {
  // ...
}


// Your new if block:
if (lastButtonDelay(2500)) {
  // ...
}

Helps with readability a bit... I think? Most of your if blocks can be functions like these. Look at my sketch and see if any of the patterns used would help you at all. I can answer any questions.

You do have good code comments.

[mc11237]

UH MAZE ING!!!!! So cool what people think of. Very impressive.

[TheArgobus]

Kazetsukai, that makes sense... I'm not really familiar with making functions and how to call them, but I'm pretty good at monkey-see-monkey-do and your example really helps. This will clean up the code for the other gadgets too.

[kazetsukai]

Originally Posted by TheArgobus

Kazetsukai, that makes sense... I'm not really familiar with making functions and how to call them, but I'm pretty good at monkey-see-monkey-do and your example really helps. This will clean up the code for the other gadgets too.

Hope its not uncalled for, I'm a programmer by trade... we tend to go into PR (peer review) mode the moment we see someone else's code. Great work.

[somewhereinusa]

I really like your idea and thought to carry it on a bit. I have fresh, grey and black tanks. I have tank sensors but, as you said, don't work right if unlevel. Perhaps something like this would work?



The main inconsistency would be body waste to the black tank. My tanks are pretty large and there's just two of us so might be able to add some percent to that figure.

The grey tank is pretty much what came out of fresh tank minus what goes to toilet.

Having results go to phone would eliminate the need for the lcd.

[TheArgobus]

That's a clever way to do it and would totally work. Just add like... 10% to the flow meter to the toilet to account for urine and solids? Out of curiosity, I did an NIH.gov search and found this (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4500995/). Apparently the average flush is 128 grams of wet fecal matter, and a rough approximation would be 128 milliliters of human waste per flush--so if your flush volume is, say, 1 gallon (3.8 liters), and you add on average 128 milliliters to that flush, that comes out to adding 3.3% or so to the volume of water that passes the flow meter. Just to be safe, I'd add 5%.


In my humble opinion, I actually prefer to use the standalone screen without a phone, but that's only because I'm borderline Luddite/Amish. A modification I wish I would've made, however, is to somehow put a paddlewheel flow sensor going into the fresh tank--that way wouldn't have to worry about how full the tank is, it would always know how much water I've added and subtracted to the tank.


These sensors are pretty simple--they're just hall effect sensors, so one could make one themselves and simply calibrate it to get the right values.

[Drew Bru]

Originally Posted by TheArgobus

In my humble opinion, I actually prefer to use the standalone screen without a phone, but that's only because I'm borderline Luddite/Amish.

Dude, Luddite? Really? I wonder what that makes me, I seriously considered just going with an old school sight glass level indicator.


I'm impressed as hell with your inginuity. We bought a SeeLevel monitor and it works alright, but it's just a rough estimate of tank percentage, not an actual indicator of how many gallons of water we have left.

[somewhereinusa]

Originally Posted by TheArgobus

That's a clever way to do it and would totally work. Just add like... 10% to the flow meter to the toilet to account for urine and solids? Out of curiosity, I did an NIH.gov search and found this (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4500995/). Apparently the average flush is 128 grams of wet fecal matter, and a rough approximation would be 128 milliliters of human waste per flush--so if your flush volume is, say, 1 gallon (3.8 liters), and you add on average 128 milliliters to that flush, that comes out to adding 3.3% or so to the volume of water that passes the flow meter. Just to be safe, I'd add 5%.

The problem is an RV toilet doesn't use a set amount of water. It flows as long as the pedal is down. Different users us different ammounts, etc. I also have a hose to rinse the "skid marks". Might be able to find some figures though.

In my humble opinion, I actually prefer to use the standalone screen without a phone, but that's only because I'm borderline Luddite/Amish. A modification I wish I would've made, however, is to somehow put a paddlewheel flow sensor going into the fresh tank--that way wouldn't have to worry about how full the tank is, it would always know how much water I've added and subtracted to the tank.

I'm lazy, it's much easier to just add a bluetooth module then read whatever the serial monitor puts out on the phone.

[jmiraglia]

Thanks a lot for sharing this. I was trying to come up with a solution to integrate water level into our custom touchscreen bus control system (Raspberry Pi and Arduino based) and this is water flow sensor idea is perfect. I'll definitely update with our finished product once it's finished.

[TheArgobus]

What are you going to use your setup for? Monitoring system stats, like water level, air temp, battery voltage? Something even cooler? I'm in the process of doing this myself, but it's so far down the list of priorities.

[jmiraglia]

Our primary use of this is for lighting control and displaying Victron Venus GX console screen that shows the state of all of our electrical/solar components.

I have all lighting wired into a bank of relays that are controlled via arduino (each light is addressable either individually or as configured groups) (arduino is also subscribed to MQTT topic and publishes lighting changes so lights can be controlled/reported on via other network based services).

We use momentary push button switches that are wired into the arduino to allow physical control of lighting groups. (this also allows for any light switch to control any/all lights without needing network to be on, so we have a master switch at the door to turn all lights off).

You can see the attached picture of the current state of this lighting control interface with water level at bottom left (will expand this so touching the water level gives you % left, gallons remaining, gallons used total, gallons used today). We'll be recording a video to cover this setup and code written to make this all possible within the next week.

[kazetsukai]

Originally Posted by jmiraglia

I have all lighting wired into a bank of relays that are controlled via arduino (each light is addressable either individually or as configured groups) (arduino is also subscribed to MQTT topic and publishes lighting changes so lights can be controlled/reported on via other network based services).

We use momentary push button switches that are wired into the arduino to allow physical control of lighting groups. (this also allows for any light switch to control any/all lights without needing network to be on, so we have a master switch at the door to turn all lights off).

You're doing more or less exactly what I'm doing with momentary buttons, with some differences under the hood.



I was also thinking of a top-down view of lights/appliances/etc so I could get status and metrics, as well as control everything from a touchscreen UI. Well done.

[jmiraglia]

I originally had an AMOLED touchscreen for my touch interface, but it was fragile and broke It was a beautiful looking display though. If you haven't already, checkout superhouse.tv, he makes/sells PCBs for momentary push buttons with RJ45 connectors already soldered on. It makes for some pretty clean wiring (even shielded if you need)