Digitise an older engine - ESP32

[Boatingbaileys]

Hi!

Thank you so much for your quick response!

Finally, I found a website that has the temperature curve! Just in case someone needs it for FAS only-one-terminal Temperature Sensor here you can find it: https://www.si-parts.com/en/temperature-...20045.html

I will try tomorrow once I get to my sailboat.

@Boatingbaileys I found another problem and don't know if you face it: I would like to keep the analog temperature clock. If I followed your voltage divider correctly, what happened is that when I connect the ESP32 to the positive and negative of the temperature sensor, the clock rise to 120º.

I am not an expert in electronics, just small projects, so I asked ChatGPT ? He is saying that sharing ground between ESP32 and the sensor generates a "Ground Loop" and that I should use an optocoupler/optoisolator.

Did you keep your analog clock? If yes, it is working correctly? Or are you just using the digital one?

Thanks!

Excellent, that will save you some time and will be useful for someone else.

I didn’t have the sharing a sensor issue as my panel only has the temperature light which works off a different sensor, basically just switching at a set temperature. 

Someone else asked this question before so I’ll try and find out if they solved it. I have a feeling you can’t measure the sensor with two different devices as you are finding out, however someone with more electrical knowledge than me might be able to help ?

One option if you trust this is to replace that display with an NMEA2k one or simply attach a 1-wire digital temp sensor near to your current one and use that instead? That might then give you some redundancy and if you ever want to change your plan in the future the engine is as it was.