question

mec avatar image

Resistive tank customization

I think it is useful for many users of old vehicles (especially campers) the possibility of customizing the intermediate values of the sensor resistance (useful for immersion sensors that cannot be replaced with floats)

Example:


200Ω=empty

200Ω+xΩ = 150Ω = 30% = 40 lt/gallon/%

200Ω+xΩ+yΩ = 70Ω = 64% = 70 lt/gallon/%

200Ω+xΩ+yΩ+zΩ = 36Ω = 98% = 120 lt/gallon/%


notes-201208-091505.jpg screenshot-20201208-085843-chrome.jpg screenshot-20201208-085402-chrome.jpg



CCGX Color Controlcerbo gxRaspberry Pi
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5 Answers
cleaver avatar image
cleaver answered ·

I looked into trying to use the existing pin sensors that are in tanks. The problem comes when as you probably know, false readings. I haven't had any tank sensor read correct in my RV. The resistor pack that is installed is based on voltage drops when wet. You would have to replace the resistors for each wire. Then each tank liquid will in fact have a different resistance based on how it conducts. (water is different than sewage.) It would become a headache just trying to calibrate.

I tried to set this up on black tank and read ohm values as tank filled. it was drastically different 3 different times.

The pins sensors can not be relied on. I bought the KUS float sensors and currently getting them installed. And I should be able to test and report in spring. Others have installed and are working properly.

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mec avatar image
mec answered ·

I agree, but in more installation Is impossible to mount a new level sender

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mec avatar image
mec answered ·

yes, this is exactly what I want to do, but there is a need to indicate the resistance values in hom that the Color control expects to read

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mec avatar image
mec answered ·

it is not a question of resistance.

Furthermore, while the clear and gray water tank always has a level indicator (the resistance values are almost identical), the black water tank has only a full switch, because the disintegrating chemicals vary the resistance of the water.

All this is needed because many of the old campers do not have predispositions for the assembly of the levels, or they have the tanks mounted in particular joints that do not allow the assembly of the level indicators and therefore you have to make do with what you have available.


The immersed contacts have their own resistance which can be amplified with further calibration resistors.

The system for each filling value in % should be able to be calibrated on a minimum and maximum resistance value.

in this way for example I can set these values:


range (170 - 220) Ω = empty


200Ω + xΩ = range (130 -160) Ω = 30% = 40 lt / gallon /%


200Ω + xΩ + yΩ = range (70 - 120) Ω = 64% = 70 lt / gallon /%


200Ω + xΩ + yΩ + zΩ = range (0 - 50) Ω = 98% = 120 lt / gallon /%


furthermore the calibration must be done for each of the 3 levels that can be read with the Color Control Gx or the Cerbo GX or Octo Gx; this is because as you rightly say the value changes drastically.

Having the possibility from software to carry out these calibrations on 4 or 5 intermediate values, would solve the life of many people and would bring great publicity to Victron for the possibility of completely replacing the old control units with their system.

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luis-gomezcala avatar image
luis-gomezcala answered ·

I have a similar situation. I got a boat with several steel tanks with restricted access to install a traditional sensor

I am looking for an external sensor like a pressure type to be able to use it


Any luck on your search?


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