Monday, January 19, 2009

Temperatures

TemperaturesI've been making steady progress on my engine monitor project.

Here you see some of the fruits of my labours. Tracking multiple temperatures.

The chart shows the steady rise of the temperature in the galley, to a more reasonable level of comfort.

You see three temperature traces, all together. That's because all the temperature sensors are still on the same breadboard while I develop and test the thing.

The plan is to glue or tape these temperature sensors onto key places related to the main engine, so as to track the overall status of the engine when it is running.

The idea being that this is an easy to implement, low impact solution to remote monitoring of the main engine.

The system, as it stands, is capable of supporting up to eight temperature sensors. I'm thinking of tracking cooling water in/out, seawater in/out, oil cooler in/out and maybe gearbox and turbo temperatures.

I'm pretty pleased with the results so far, with one of the sensors now working off the breadboard, and can tell you that the fridge at home is at least as cold as 7C - at that point I was encouraged to 'get my wires out of the fridge'.

I'm guessing that without the rev counter and pressure sensors, which I will work on next, that this setup will be of interest to quite a few people I know.

2 comments:

  1. Anonymous2:33 PM

    I wonder why the readings seem to follow those 1/2 degree steps. It seems odd that you have more than 1/2 degree resolution in the reading (though not in accuracy, I think) but the readings seem to like to stick to the 1/2 degree boundary, then jump up in a steep slope to the next 1/2 degree.

    How will you build your rotation sensor? I tend to favour epoxying a small rare earth magnet to the cam or main shaft and then watching it turn with a hall-effect sensor. This arrangement works well, even when all sorts of dirty oil is likely to be splashing about.

    You are going to wind up with weird instrumentation all over Lady Jane -- water level in bilge in 3 places, seawater temperature, freshwater level, holding tank level, battery readings, fuel, oil, coolant and turbo pressures. Do you have an overall architecture in mind for how all that instrumentation will connect together?

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  2. Hi Anonymous

    I've averaged out the actual readings to make the graph look a little neater.

    The actual sensors, DS1621 have a 1/2 degree resolution, and the charts had a zig zag effect on transition from one reading to the next without the averaging.

    I'm planning on trying a photo-reflector, SY-CR102 on the shaft - some way away from all the oil and dirt. If that fails, as I'm a little concerned for how long that will stay clean, then the Hall effect will be my next bet (thanks for the idea).

    The rough plan for instrumentation on Lady Jane is to collate it all on a central server, then use it from there via some kind of intranet app, so any connected PC can access the data. Both current and historical.

    I have all sorts of ideas on how the data can be managed/displayed. Mostly these revolve around the concept of pages of user definable fields:
    Engine
    Boat
    Navigation
    Domestic
    ...

    I'll just have to see how that all develops as things evolve.

    Cheers

    Tim

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