EmonTx Arduino Shield
I should pbrlaoby have used some paste, but couldn't be asked I've checked the temperature of the engine block vs. that reported by the sensors, and it was within 1 degree, so good enough.The cuboids are low voltage/power signal relays, 5V which can be driven directly from the Arduino's pin outs. One of them is used to drive the remove switch functionality of the generator control unit (DeepSea 3110), i.e. to turn it on or off.The other relay is to turn the radiator fan on and off, but that relays is used to drive a second automotive relay which can handle the current. There's a third relay there, which is the solid state relay for switching the 80W extractor fan and of off, but I've not connected it yet.