- Jun 5, 2016
- 5,618
- Boat Info
- 410 Sundancer
2001
12" Axiom and 9" Axiom+ MFD
- Engines
- Cat 3126 V-Drives
So, appears it simply draws a line between points and interpolates a relationship between temp and voltage; the more points of data the more applicability to a thermistor curve and consequently the more accurate. If this is true I would recommend you remove from the engine the temperature sensor and put in a pot of water then measure resistance and water temperature concurently as you heat the water to boiling; that is what I did. Then you can calculate the voltage measurements to load into the Chetco.
Tom
To your first point, I believe this is what it is going on.
As to off boat testing and calculated voltages, I'm not sure I can do this. I believe the Checto is reading a voltage, doing some preconditioning and processing of the signal, then it is outputting a scaled 8 bit value (0-255). The unit then looks up that value in the calibration table and outputs the associated temperature (or other real world value depending on whats being measured). The benefit is you can calibrate any sensor (resistance low->high or High->Low. But I cant input a raw voltage. The downside, is you have to identify the 8 bit value via software and correlate that to your real world value in real time. My next job is to validate what being displayed on my MFD vs the temp measured at the sender. I'll graph it and see where I am.
However, If I were to install this on the engine I believe this has a switch selectable resistance mode reading the resistance of the senders, and I think you can dial in the exact resistance vs temp/pressure reading. I have not attempted this yet, but in talking to Chetco, this would be the easier and more accurate method.
Just curious, what would you consider acceptable accuracy? Considering the current analog gauges, I probably would be happy with +/-5 deg. Just reading the gauge I could be that far off. What I'm really after is an alarm where the temp/pressure quickly deviates from the norm.