Propane tank

[Kilo95]

I live up north and out in the country so I have a propane tank. I don't know whether you want to call it laziness or whatever but I don't like going out into the cold to check the level on the tank. I was thinking about the water meter mote. Could that be modified so it would alert me when the needle on the propane tank gets to 20%? If someone has a different suggestion please let me know. Thanks

[Sergegsx]

cant help you, but maybe a picture of the installation can make it easier to find a solution.

[Kilo95]

Here's where it'd go

[jra]

I think the water meter mote is designed to count rotations of a spinning wheel whereas you are looking to detect the position of a needle on a dial.  There are commercial solutions, see http://fuelminder.biz/will%20call%20monitor/will%20call%20monitor.html for one example.  I believe this relies on a specific gauge (Rochester R3D-LP http://www.rochestergauges.com/products/R3D-LP.html) that allows for an external Hall effect sensor.  If you don't have a gauge like this detecting needle position is a relatively straightforward pattern recognuition problem.  The not straightforward part is transmitting an image of the dial using a battery-powered Moteino sitting outside in the cold.

Posted before I saw the picture.  Your gauge is remote ready so you can use a Hall sensor to read the position of the dial.  Either reverse engineer the sensor listed above and build your own or figure out which wires carry the sensor information and transmit that via a Moteino.

[TomWS]

I live up north and out in the country so I have a propane tank. I don't know whether you want to call it laziness or whatever but I don't like going out into the cold to check the level on the tank. I was thinking about the water meter mote. Could that be modified so it would alert me when the needle on the propane tank gets to 20%? If someone has a different suggestion please let me know. Thanks

Load cell under the Tank?  Be pretty accurate...  Somewhere in this forum I saw someone using these.
Tom
UPDATE: Here's the thread: https://lowpowerlab.com/forum/index.php/topic,1091
However, looking at your photo, you're tank is full.  Relax...   

[TomWS]

Posted before I saw the picture.  Your gauge is remote ready so you can use a Hall sensor to read the position of the dial.  Either reverse engineer the sensor listed above and build your own or figure out which wires carry the sensor information and transmit that via a Moteino.

@jra, Good suggestion.
@Kilo95, if you use a 2 or 3 axis magnetometer, relatively inexpensive from Honeywell or Xtrinsic MAG3110 from Freescale, you can read the angle almost directly.  I didn't realize the needle was magnetized.  Good to know.  I might look into this.   Of course your fuel company might get cranky about blocking the meter.

I think the load cell would be the way to go.  I'd do that if my tank wasn't buried!

Tom

[Kilo95]

I think I might try the magnetometer. Thanks for the suggestions. They only come out when I call them. Don't think they'd say anything. If they do, I'll just switch to natural gas. 

[TomWS]

They only come out when I call them. Don't think they'd say anything. If they do, I'll just switch to natural gas. 

Wow!  I don't have Natural Gas as a choice at either of my two locations and, if I told the LP supplier, "Well, I'll just look elsewhere." they would tell me, Great, we'll suck out the gas that's still there, take the tank and all the hookups and, uh, good luck finding someone else...

Sigh. However, please keep us abreasted of your progress on this.  I really would like to install sensors on my various tanks.

Tom
PS: I like the Freescale sensor but it will be a challenge to solder.  However, I like it so much that I'll probably try it on another project I'm working on so let's stay in touch.

[Kilo95]

Jra, I'm thinking I could get the fuel minder setup you suggested and run it the 40' or so into my garage (where it's warmer and batteries would last longer) and try to figure out how to hook up a moteino to it there thanks for the suggestions

[TomWS]

(where it's warmer and batteries would last longer)

What temperatures do you have?  A lithium primary would get you to -40C (coincidentally -40F)...

Tom

[Kilo95]

Coldest I've seen is -25 to maybe -30. So that would work with a few degrees to spare

[Felix]

I think the EESY310 would totally work for this. It can tell when the needle is beneath it very well if the background is an IR reflective color like white. The sensor is very responsive and has a hysteresis so it shouldn't give you a false read. The dial might need to be covered if sunlight hits it or light throws it off, experimentation will tell for sure.

FWIW if there's enough "magnet" on that needle even the omnipolar sensor I use for the garage doors might pick it up.

[TomWS]

Coldest I've seen is -25 to maybe -30. So that would work with a few degrees to spare

The other thing about your project is that it can be EXTREMELY low duty cycle.  I would expect reporting in once every 24 hours would be more than enough to know when you need to refill. 

Let's see... 40mS (80 if you needed retry) to report it's reading @~20mA (average current) max, 86,400 seconds to hibernate, drawing less than 1uA.  Yup, your battery leads would rot before your battery was dead.  Of course, Joe would try to run it with a coin cell battery.

Tom

[Kilo95]

Sounds great. I'll have to look at it. My tank has a massive lid on it that I keep shut which would keep the light to a minimum

[Kilo95]

so felix, it looks like i could just purchase the WaterMote kit with the EE-SY310 for this application, am I correct? with maybe a few minor changes