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panterlo avatar image
panterlo asked

Cerbo GX - tank sensor 0-180 Ohm issue

I have just installed Touch 50 and Cerbo GX and a few other Victron products. But I can't understand why Victron have limited the tank level sensor inputs to 0-180 Ohm (Europe) or 240-30 Ohm (US). This is all wrong since newer tank sensors in Europe actually have 0-190 Ohm and like explained by Wema:

https://wema.co.uk/pages/faqs

EUROPEAN vs AMERICAN ohms


What's the difference between the European and American resistance specifications?

  • European spec. products work on a variable resistance from 0 ohms at empty to 190 ohms at full.
  • American spec. products work on a variable resistance form 240 ohms at empty to 30 ohms at full.

Wema, KUS and many other manufacturers are today distributing only 0-190 Ohm sensors across the European markets so this makes the Cerbo GX unable to accurately display the tank level in newer installations / boats.

Could this be added to the Cerbo GX in an upcoming firmware release ?


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5 Answers
wkirby avatar image
wkirby answered ·

Updated- Now released.

This is now released in 2.60 versions and later.

There is now a third "Custom" option where the Empty and Full resistances can be set manually.


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panterlo avatar image panterlo commented ·

This is great news. On the same note there is also one other missing point. In a grey water tank you are interested how much is left and not how much is in the tank, e.g the reverse against what the display shows today.

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Kevin Windrem avatar image Kevin Windrem panterlo commented ·

All tanks show fullness however alerts occur depending on the fluid type. Fresh water for example warns when tank level is BELOW 20%; Gray and Black water warns when tank level is ABOVE 80%. I think it works well the way it is and might be confusing with gray/black tanks showing air rather than fluid.

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bturgidson avatar image bturgidson commented ·
Having just converted the tank monitors from CZone to the Cerbo GX, I had to deal with this issue as well. Using the standard 0-180, there was a 5% delta in the tank levels. Once I programmed a custom range, the numbers fell back into place.


We did however, run into a totally different issue. When power is applied to my navigation instruments, the resistance readings, per the Cerbo setup, begin to increase. Transmit on the VHF and they go off the scale. Turn the instruments off, and they fall back to normal. Instrument package is from Garmin and they are connected via the N2K network. The sending unit heads were simply transferred from the CZone interface, to the Cerbo, nothing else was done. Does the Cerbo read the sending units in a different fashion than the CZone? Has anyone else seen this behavior, and if so, how was it rectified?

I am working off the assumption, correctly, or incorrectly, that this is being monitored through a 4 - 20 mA current loop.

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Richard Pearce avatar image Richard Pearce bturgidson commented ·
I too have a similar issue. I suspect it’s down to the sender using the common negative and although this is a heavy wire, any power drawn on it s causing sufficient voltage drop to affect the gauge reading. I’ve not got round to rectifying this as it will need an extra wire running separately for the gauge only.
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bhcreasy avatar image bhcreasy Richard Pearce commented ·
I'm experiencing the same thing, tank readings jump up by 10% when I turn on my electronics. I'm using the Cerbo GX with four 0-180 Ohm tank level sensors. I don't understand why this happens, and wonder if you found a way to overcome this issue. help please, this is very frustrating.
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arturo avatar image
arturo answered ·

Hello!


This new software modification is super important, we camper vehicles and we did not find high quality sensors with the current operating resistances 0-180 or 240-30.


We look forward to it.

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Wes Humpage avatar image
Wes Humpage answered ·

What are the chances of bumping the higher resistance level to 350 Ohms?


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devodave avatar image
devodave answered ·

The custom resistance option means the issue can be easily overcome so this isn't a biggie, however a few more options on the resistance types would be an easy thing to do in firmware and would make commissioning that much easier for newbies.

Marine tank senders are often 10-180ohm rather than 0-180ohm or 0-190ohm. Please list *all* common options in the dialog.

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Robert Lener avatar image
Robert Lener answered ·

Cerbo GX Sensor value limited to 300 Ohms.

Our old water tank sensor is about 390 Ohms when full.

Any solution except buying a new sensor?


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