I installed a fill plate for a fresh water tank and am looking for a way to tell how full it is from inside and when to stop filling from outside. The fill plate is next to a cabin window which has a bulkhead that some kind of indicator can be mounted to. I have some contactless level sensors and can program them to work with an Arduino if using an LED, LCD or other screen. What types of indicators have you found that are visible in sunlight or semi-shaded spots and do not require a lot of power? I'm not opposed to an analog style meter
Sunlight visible meter, indicator, LED, LCD, etc.
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For an outside "stop fill" indicator, I think you could use a whistling device that is sold for fuel tanks. As soon as the water level reaches the whistle in the vent tube, it stops whistling.
As far as a level sensor, just use a contact less sensor and a display inside.
As far as a level sensor, just use a contact less sensor and a display inside.
For an Arduino compatible display that you can read in bright light you can consider E-Ink displays like at LCDs & Displays, eInk / ePaper Products Category on Adafruit Industries. That might be overkill for just checking tank level while filling though.
If you keep track of your current filled capacity, then you could use a tool like this to roughly measure how much to add. (i.e. 50 gallon tank about 50% full... need to add 23 gallons)
Orbit digital flow meter.
I've been using one for about 6 years. Has worked well. No overflow experiences. You can also add a cut-off valve to shut water off at the boat while filling.
Orbit digital flow meter.
I've been using one for about 6 years. Has worked well. No overflow experiences. You can also add a cut-off valve to shut water off at the boat while filling.
I've never heard of such a device but it sounds perfect! I have a 1/8" line inside the PVC pipe for a vent already. I could also use a peizo speaker to indicate the level from inside
I actually came across and bought this exact type of display a couple hours after posting! How careful do you have to be about refreshing/reinitializing to avoid image burns?
My tank is only 4-5 gallons. I think a cut off valve would cause an overflow on deck. Doesn't hurt anything of course
I thought about a cut off solenoid/valve but that would result in overflow on deck. Not the end of the world but a slight unpleasantry
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After some thought, I decided to go this route: The contactless level sensors came with a PCB to connect them to. There's an LED for each sensor. This will be the interior indicator. The exterior indicator will be an Arduino controlled peizo element mounted inside next to the fill port. This will beep according to the tank level.
For now I will install a timer relay module set for 15 minutes. When a NO momentary switch is pressed, it activates the relay which in turn powers up the Arduino and sensor LED PCB. It'd be nice to put a light sensor of some sort in the fresh water fill pipes to detect when the cap is removed but I have other projects on my list that are much higher priority
For now I will install a timer relay module set for 15 minutes. When a NO momentary switch is pressed, it activates the relay which in turn powers up the Arduino and sensor LED PCB. It'd be nice to put a light sensor of some sort in the fresh water fill pipes to detect when the cap is removed but I have other projects on my list that are much higher priority
Sounds like a clever solution.
For future reference I don’t think image burn-in is any kind of issue with E-ink. They’re designed to keep the same image for a very long time. The other nice feature of them is they only use battery power when being changed. They can continue to display an existing image without consuming power. The downside is it’s not backlit so night viewing needs a flashlight, and it refreshes relatively slowly so it’s not great for dynamic graphics.
For future reference I don’t think image burn-in is any kind of issue with E-ink. They’re designed to keep the same image for a very long time. The other nice feature of them is they only use battery power when being changed. They can continue to display an existing image without consuming power. The downside is it’s not backlit so night viewing needs a flashlight, and it refreshes relatively slowly so it’s not great for dynamic graphics.
I'm also slightly hesitant to go the light sensor route as it will be a constant draw on the battery but so far it hasn't been an issue leaving a class D amp sitting idle while I'm away. The 100W solar panel keeps the battery topped off.
For filling a tank I think a refresh rate as low as 1Hz could work. This page mentions refresh rates, re-initialization and potential damage related to "burn-in". I honestly haven't read much into this technology but it's quite incredible that we can control ink with such precision!