My current setup is a Cerbo GX monitoring solar controllers, inverter/ chargers, batteries, and fuel and water tanks, then sending data to Garmin MFD. My question primarily concerns tank level sending units. Ours are Euro spec 0-180 ohm units from KUS. We double and triple checked all of the settings and they are correct. however, all tank levels read 5 to 6% higher than the previous czone monitor which we found to be fairly accurate. All that was done was to move the sending unit wires over to the Cerbo. It has also been noted that when power is applied to the Garmin equipment, tank levels increase by another 5%. I then monitored all of the sending unit resistance readings via the Cerbo, and they appeared to be functional. Again cycled power and noted that resistance increased as the Garmin network was powered up. Remove power from the Garmin equipment and resistance reading drops. Even more perplexing is that when powered up, and the vhf radio is transmitting, the Cerbo indicates that the resistance and displayed fuel levels move up towards maximum. 184 ohms and 94%. Quit transmitting and they fall. Is it possible that there is a additional current loop of some kind cause the errors?
