October 2015

heater controller This months boat distraction has been making a boat heater and logger. Using one of these will allow me to avoid winterizing the boat and capitalise on those few autumn and spring days when the conditions are perfect and you want to get out on the water!
I used the Arduino MPCU I was using for my energy usage logger and purchased a couple of NTC thermistors.
The Arduino wakes up (Using the Narcoleptic library to minimise power consumption) every 5 minutes and checks the ambient air temperature and also the temperature inside the engine bay. If either go below 5 degrees it fires up the heater, which it controls within an upper and lower set point using a solid state relay driven by one of the Arduino Uno's digital outputs. To try and get even more life from the 9v battery the thermistors are only powered when the Arduino wakes up, using a digital output pin. All the temperatures and the heater state are logged to SD card as a check.

NTC thermistor