question

silent-power-australia avatar image
silent-power-australia asked

Cerbo GX resistive tank inputs.

Hi community. I have installed a Cerbo gx on a catamaran. My issue is trying to connnect the 4 tank inputs. If I parallel the sender and earth from the existing gauges to the Cerbo tank inputs I get incorrect inputs on the Cerbo. Is the answer a tank 140 ? I am figuring that when the existing gauges are powered they produce a voltage signal not resistance can any body confirm this and that a tank 140 would be the solution.

cerbo gx
2 comments
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

silent-power-australia avatar image silent-power-australia commented ·
Great information thank you. Does the converter change signal to digital ?
0 Likes 0 ·
derrick thomas avatar image derrick thomas silent-power-australia commented ·
No it does not. The purpose of the converter is to take the resistance values from the sensor (parallel connections alters the resistance value being read by the gauge) and allows you to adjust the reported value to what the gauge expects to see for a given level. The difficult part is that unless you are able to remove the gauge from the tank in order to manually move the float, and adjust the converter output for each level settings, (converters typically have program settings for 1/4 tank increments from empty to full) it takes some trial and error to get it right.


If at all possible, I would highly recommend looking at the mopeka pro universal sensor, and leave the existing sensor and gauge alone.

0 Likes 0 ·
3 Answers
Paul B avatar image
Paul B answered ·

As far as I am aware you cat parralle the gauges to the cerbo, you would need a separte sender for the cerbo and leave the existimng gauges as they are

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

derrick thomas avatar image
derrick thomas answered ·

You need to determine with a certainty if you have resistance sensors or voltage sensors. The cerbo only works with resistance sensors, and the tank 140 only works with voltage based sensors.

2 comments
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

silent-power-australia avatar image silent-power-australia commented ·
Yes they definitely resistive 0-190 senders. When hooked in parallel with gauges and Cerbo the resistive values measured are 60-80 ohms. Very weird.
0 Likes 0 ·
pwfarnell avatar image pwfarnell silent-power-australia commented ·
No, it is not weird when you understand how a resistive gauge works. To measure resistance the gauge passes a current through the sender and measures the voltage drop to calculate the resistance. If you have 2 gauges, both are trying to send a current through the sender so the voltage drop gets messed up so neither gauge measures correctly.
0 Likes 0 ·
silent-power-australia avatar image
silent-power-australia answered ·

They are definitely 0-190 resistive senders. When wired in parallel with Cerbo and gauges I get resistance of 60-80

1 comment
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

derrick thomas avatar image derrick thomas commented ·
Parallel gauges can be used with resistive type sensors, but they are not a simple plug and play. You basically have two options. First, and simplest, is to use a spdt (single pole, double throw) toggle switch. Connect the sensor lead to the COM pole, and a gauge to each of the pole 1 and 2. This way only one gauge reads at a time and the sensor remains accurate. Second method is to install a signal converter for each gauge. (Google it, there are converters specifically made for resistive sensors). You will need to adjust each converter for the correct gauge display. It requires a bit of setup but it is worth it if you want both gauges to display accurately at the same time. I have this setup on my Diesel tank and it works great.
0 Likes 0 ·