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Water Meter Ultimo


  • Fyko van der Molen
    Fyko van der Molen on

    About a year and a half ago we identified the need for a dedicated water meter that was always visible and active. People were buying this garden hose device that is hopelessly inaccurate and can only be read by climbing under the caravan. The only other alternative was a gadget that crudely measures 4 different levels by electrically shorting studs drilled into the side of the tank. With a broad, flat tank that’s not much of a solution.

    So we made a display box that can stick anywhere, takes power from the caravan battery when the pump is enabled, and is wired to a flow sensor inserted into the hose between tank and pump, normally under the floor.. The display is backlit so it can be seen night or day and it remembers the last outflow count when it is switched off.

    It displays the quantity of water drawn from the tank since the last fill. The outflow is zeroed by pressing a button when the tank is is filled. The display auto-dims after 30 seconds to reduce energy consumption (power draw is about 70mA).

    Then we wanted to show water remaining in the tank, so we provided the means to enter the tank size so the necessary calculations could be performed to indicate the percentage of tank capacity remaining.

    Then we added an inflow sensor so the tank could be partially replenished from rainwater or similar and the outflow indication would be adjusted accordingly. The outflow can only be zeroed when the tank is entirely filled.

    Then we found there were small variations from one sensor to another, and the mounting orientation could also subtly affect the measurement accuracy, so we added a user-entered calibration factor to eliminate these errors and achieve potentially 100% accuracy. We also added the means for the user to switch between all popular sensor types.

    Then we were asked to add a user-settable Water Hog alert buzzer to warn of profligate water usage (user-settable to between 1 and 20 litres of continuous flow) . We also added a buzzer alert when the water resource drops through 20% remaining in the tank.

    Then we added the equivalent of a trip meter in a car’s odometer, called a Glug meter to measure specific occasional water draws without needing to do any mental arithmetic on the indicated total outflow. Since the meter measures with a precision of 10mL it is suitable for just about any water metering application, including cooking projects. You use the button to zero the Glug meter and then the outflow counts both meters in tandem.

    Since the Main meter and the Glug meter are both zeroed by the same button it is possible that sooner or later the wrong counter will be cleared – not serious for the Glug meter but awkward when the Main outflow is lost. Therefore we added the means to retrieve the last outflow count of the Main meter if it is erroneously zeroed (3 taps on the button).

    For caravans that do not have a sophisticated power panel we can optionally add a high-precision voltmeter to continuously display the received battery voltage.

    That’s where we are now, thanks to the many thoughtful users who suggested many of these improvements and extensions.


    Athol Hughes
    Athol Hughes on

    Please advise what is required to display battery voltage.

    And how is it shown on the LCD – there doesn’t seem to be enough space in the display area.

    Many thanks.


    Fyko van der Molen
    Fyko van der Molen on

    The battery voltage is measured from the input power cable.

    The unit draws less than 70mA so the volt drop on the power cable is negligible and so we accurately reflect the voltage at the power distribution panel. This voltage in turn should be very close to battery voltage unless a very big load is being serviced – and this in itself will be significant info.

    Because the Glug Counter is used only occasionally. (elsewhere I’ve likened it to the Trip meter on an odometer), the lower line of the display can be dedicated to Battery Voltage most of the time:

    One press of the button and the display reverts to the Glug Counter in the next post


    Simon Tasman
    Simon Tasman on

    Thanks to this water meter I was able to establish without doubt that what was sold to me as a 105 litre tank is actually an 86 litre tank.

    I was wondering where all the water was going – no leaks to be found and nobody but the wife and me using it.

    Now I know – it wasn’t going anywhere, I never had to start with! Amazing.


    Athol Hughes
    Athol Hughes on

    I have a 3kg electronic kitchen scale. I put an empty 2L bottle on it, it reads 45g. Then I pump in water from the sink tap until the scale reads 2045g, At this point the water meter reads either 1,99, 2,00 or 2,01 litres.

    So the accuracy is -0,5% to +0,5%. A teaspoons more or less per litre of water not bad.

    When I drained my supposedly 80 litre tank it ran dry at 62 litres, and this was with the nose down to get the last drops out of the tank.

    But now that I look closely, nowhere in the documents am I promised 80 litres. That’s what I was told verbally. The trailer specs don’t specify tank size, and neither does the equipment list on the invoice. So I took their word for it without anything being put into writing. Amongst the list of other accessories it’s easy to miss.

    Now I carry a blue plastic 20L can to top up with when the tank runs out. At least I know exactly when the tank is going to run out – which I didn’t before. Every time an unwelcome surprise.

    I wonder how I got by without before.

    My plan is to use a small pump powered from the Hella plug to transfer from the jerry can into the tank using the drain outlet in reverse. If I put an inflow sensor into that hose then I’ll still have a pretty good idea of the state of the tank. And without the back-breaking strain of tipping a jerry can into the filler neck, with a funnel spilling half the water. But that will have to wait till next year.

     


    Fyko van der Molen
    Fyko van der Molen on

    Water Meter Monitoring from Mobile Phone

    You can now read your Water Used and Water Remaining figures from your mobile phone using our free Android phone app.

    You can also clear the Outflow Count using the same app.

    All existing units are upgradeable – turnaround time is 2 days max.


    Fyko van der Molen
    Fyko van der Molen on

    Screenshots relating to the previous post


    Fyko van der Molen
    Fyko van der Molen on

    Screenshot relating to the previous post:


    Fyko van der Molen
    Fyko van der Molen on

    Why use a water meter? People ask.

    To conserve water.

    This doesn’t apply if you’re on the South Coast parked next to a standpipe delivering unlimited free water.

    But if you’re deep in the hot, dry and dusty Kalahari sticks and you’re desperate for a blissful shower but don’t know whether your water budget will stand it. That’s when you need a water meter.

    It will tell you:

    • How much water you have,
    • How much water you don’t have any more,
    • It will buzz you when you exceed you (self-imposed) water allocation limit,
    • It will buzz you when you get down to a quarter tank (After which your allocation limit is automatically halved),
    • It will keep track of opportunistic partial replenishments,
    • It will separately meter out small quantities for cooking etc. so you dispense with your measuring jug,
    • It will show you the flow rate in Litres per Minute while the water is flowing,(NEW)
    • It will repeat this display on your mobile phone.

    It’s not for the boys obviously, but definitely for some of the men.


    Josef Konrad
    Josef Konrad on

    Very useful addition is that flow rate indicator.

    Now you can figure out in advance how much a 3 minute shower is going to cost, as opposed to say a 4 or 5 minute shower. I’m going to enjoy it.

    Can I get an upgrade?


    Fyko van der Molen
    Fyko van der Molen on

    Surely. You know where to send it.

    Allow an extra day because of the post-holiday upgrade volumes.


    Fyko van der Molen
    Fyko van der Molen on


    Fyko van der Molen
    Fyko van der Molen on


    Josef Konrad
    Josef Konrad on

    I would like a meter that can tell me how much water I’ve put into a tank through the filler neck.
    I need this firstly because I add purification tablets proportional to volume of water added and secondly I’d like to know how big the tank actually is.

    And I DON’T want that silly Gardena gadget that goes on a garden hose.


    Fyko van der Molen
    Fyko van der Molen on

    We in fact have exactly such a feature. It’s not well known because inlet sensors are used only by a minority.

    The normal application of an inlet sensor is to lurk quietly in the inlet tract and reduce the Outflow Counter by the equivalent amount as long as the tank is not overflowing. It requires no user input – you forget it’s there.

    However if you specifically want to meter inflow water you can do so, What you do is simply clear the Outflow Counter with the pushbutton and then, before any further water is drawn from the tank, inflow the desired amount or until the tank is full. The intake water quantity is shown in litres like this:

    Only the top left quantity is relevant.

    As soon as the outflow sensor detect activity the display reverts to the usual.

Viewing 15 posts - 1 through 15 (of 15 total)

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