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lshantz avatar image
lshantz asked

Cerbo GX - tank connect issues

I have a 2001 Safari Panther with the old tank sending units. They use resistance Ohm for what I believe is 4 levels. Empty, 1/4, 1/3/ 3/4 and full. I have hooked this up to the tank level block and having issues.

1. It has locked up the Cerbo GX tight. I am unable to move from the current screen. The only way out that I have found is to remove power completely and let it reboot.

2. If I select European setting, instead of USA settings, it does not lock up, but reads incorrectly. I jumped across the sensor to show a full reading, and it reads 4%. If I change it back to USA settings, it locks up again.

Any help greatly appreciated.

cerbo gx
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safiery avatar image safiery commented ·

A word of caution. The "resistive" block or plug senders may not output a linear resistive signal. There is ant any tested here in Australia that work effectively.

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mvader (Victron Energy) avatar image
mvader (Victron Energy) answered ·

Hi @lshantz, sorry to hear that. Which firmware version is installed on the Cerbo? (See Settings -> Firmware) And what do you mean with locked up tight?

Perhaps its possible to share a short video that shows it?


thank you, Matthijs

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lshantz avatar image
lshantz answered ·

I mentioned it to my vendor and that is the first thing he had me do was to put the latest Firmware on it. It was current as of yesterday.


I can do a short video I'm sure. Basically when I say it locks up, the screen will no longer allow me to move around. Kind of like a computer that is hung. Just sits there. Very easy to duplicate. I would really like to figure out what I need to do, to get valid tank values though. It is over 100f right now. I'll try first thing in the morning. :)

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Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

Hi @lshantz

Any chance that your sensor is putting out a voltage instead of a resistance? maybe still connected to a power source or (floating) ground?

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lshantz avatar image lshantz Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

I would bet $20 it is not, but I didn't think to check it. I will go check that, and tone the wire as well to make SURE I'm on the right pair. Boy wouldn't that be embarrassing. I kind of hope that is it. Would be a lot simpler. I could also try to hook up the other 2 tanks and see if I have the same issue eh?

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lshantz avatar image
lshantz answered ·

Well I went out this morning, and the computer made a liar out of me. I could not get it to lock up. ?? Not sure if some value has changed, but something is different this morning.

Something needs fixing on your web server. The little movie clip is less than 1mb. 419kb and it says it is too big. ??

In any event the firmware version was on the video clip. I believe it is 2.54. So since US Ohms is set to 30- and European is 0- AND it reads so low when it should read full, makes me wonder if the Ohm values are too low and thus the reason for the "short" in US mode. ??


Is there a way to adjust the unit to calibrate it with the existing Ohms to show full, empty etc?


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img-20200615-064834.jpg (5.1 MiB)
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mvader (Victron Energy) avatar image mvader (Victron Energy) ♦♦ commented ·

Hi v2.54 is the latest version; so thats good!

& good to hear the lockup is gone.

yes that file size limit is annoying. I know. Its a hosted service; not fully under our control I’m afraid. But there is dropbox or other alternatives luckily.


futher tweaking and calibration: not in the version you have. But we are working on that, and its coming in v2.60. I expect that to be available in one or two months.

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lshantz avatar image lshantz mvader (Victron Energy) ♦♦ commented ·

"But we are working on that"

On other options for tanks, or upload size?

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mvader (Victron Energy) avatar image mvader (Victron Energy) ♦♦ lshantz commented ·

hi, more options for tanks. Read through here, and previous v2.60 beta posts:

https://community.victronenergy.com/questions/53096/venus-os-v26028-available-for-testing.html

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Kevin Windrem avatar image
Kevin Windrem answered ·

The probe type tank sensors are extremely high resistance (68K, 100K for the two middle sensors, 0 ohms for the full sensor). The system relys on the conductivity of fresh or waste water to make a connection between the common probe and one of three level probes so the resistance of the fluid adds to the resistors connected to each probe. There is a suitable pull up in the sensor panel then three comparators connected to the indicators for 1/3, 2/3 and full.

Typical resistive senders are in the under 300 ohm range.

Connecting the tank sensor directly to a Cerbo tank sensor input will certainly register as an open to the Cerbo inputs whether or not the panel's pull-up is engaged or not.

Shorting the full probe to ground would register as a short circuit.

I do not know of any adapter to convert the high impedance probes to a resistive sensor equivalent.

Probe sensors have limited resolution: < 1/3, < 2/3, > 2/3 (full). Buildup inside the tank can give false readings. For this reason, many look to other sensor types for more reliable and higher resolution solution.

Given the limitations, how many people would be interested in such an adapter? If a circuit diagram was provided, could you build it our would you need something ready to install?

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lshantz avatar image lshantz commented ·

I guess I'm confused somewhat. There are literally millions of tanks set up like mine. So it is not like this is a rare set up. I'm guessing Europe does it totally different than the USA? So why only resistive if what I have is so common?

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mvader (Victron Energy) avatar image mvader (Victron Energy) ♦♦ lshantz commented ·

Hi, my two cents: the Cerbo GX is a product made for many different markets. Only a few % of all installations need tank levels at all. And (in europe for sure) 0 to 180 Ohm, or similar, are the most popular tank level senders used in Marine applications - our background.

That probably explains the why.

So, the Cerbo GX (& Venus GX) hardware can work with tank senders putting out anything between 0 and 240 Ohm.

Also, they can read tank levels from NMEA2000 bus. Not compatible with all tank senders unfortunately, but compatible with some. Details in the manual.

We're currently working on a (USB) accessory, that adds 4 to 20mA input & 0 to 10V input. More details here:

https://community.victronenergy.com/questions/47324/looking-for-input-4-to-20ma-senders.html

Quite frankly, once we've finished all the software work thats going on in v2.6o to fully feature our tank inputs, as well as add that new accessory to take more sender types; I'll be done with doing anything that relates to tank levels for a long time :-).

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lshantz avatar image lshantz mvader (Victron Energy) ♦♦ commented ·

Well keep up the good work. I believe having solutions for the RV market will vastly increase interest in the RV market.

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Kevin Windrem avatar image Kevin Windrem mvader (Victron Energy) ♦♦ commented ·

mvader, what's the current plan for updating the NMEA2000 tank interface to support multiple tanks from the same device? At one point this was on the 2.60 list as a possibility.

I've got the tank repeater solution that works well at least for See Level N2K and it's available to all who need a solution. So just asking to learn what the current Victron plans are. Thanks so much for all you do.

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Kevin Windrem avatar image Kevin Windrem lshantz commented ·

You are correct. Nearly every RV has these extremely basic tank indicators. I think the reason you don't see interfaces for these sensors to things like Cerbo and Venus are that they have very limited resolution and don't work very well. The probes can easily give false readings due to buildup in the tanks, especially black tanks.

As far as I know, Europe and US use the same system for these indicators. It's the resistive senders that are different Europe full = 190 ohms, empty - 0 ohms. US full = 30 ohms, empty = 240 ohms. Victron tank inputs accommodate both and with software currently in beta there are more tweaks to deal with tank geometry as well as full/empty limits.

I'm guessing that resistive float sensors are the second most common tank level indicators in RV use which is probably why Victron has these inputs on their Cerbo and Venus GX units.

There are other tank sensor options but integration with Victron is limited at least for now. RV-C tank sensor systems are not supported. NMEA2000 tank sensor systems are limited to 1 tank per system until Venus changes are made in a future release. I do have software that overcomes the NMEA2000 limitation now. Designed for SeeLevel N2K sensor systems, it "should" work on other NMEA2000 multi-tank sensor systems. The biggest down side to these other systems is cost.

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lshantz avatar image lshantz Kevin Windrem commented ·

I think they would increase their market share vastly if they supported the very common tank measurement systems in US RV's. In any event, thanks for the complete response. I'll just have to go with a non Victron solution. :(

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childcarepro avatar image
childcarepro answered ·

lshantz,

I agree a LOT of people have KIB sensors. I agree IN THEORY that supporting this sensor type might be helpful to many to have plug-and-play functionality with existing sensors.

HOWEVER... I feel that MOST people who:

1. Spend $600 on a Victron Cerbo GX/GX Touch system

2. Have $2K-$10K solar electric setups

3. In a $60-200K rig...

...would NOT be satisfied with stock KIB sensors with - not 0.01% resolution, not 1% resolution - 33% resolution (and inaccurate at that). IMHO wanting to know whether one's black tank is 67% full or 99% full is MUCH more reasonable than switching to an inferior monitoring system because it supports the crappy sensors one has.

Personally, for me, coming from an $80K Airstream with SeeLevel II tank meters (1% resolution), my wife and I are SUPER UNHAPPY our new $160K Winnebago Via (Sprinter chassis class A) came with these nearly useless tank sensors. Shame on RV manufacturers for choosing a few dollars of profit over providing good tank monitors.

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