Arduino-based GUI for active grille block

[Piwoslaw]

Originally Posted by CigaR007

I have been observing the coolant temperature for the past few days. With the shutters SHUT, at constant speeds, as soon as the coolant temp reaches 95-96C, it stabilizes and gradually drops to 91C. The cycle repeats every 5 minutes or so.

This leads me to consider that the Radiator fan is running on low speed and the trigger temp seems to be around 96C.

This is a good example why knowing when the radiator fan is ON is useful.

That does seem correct. My turbodiesel's fan turns on at 98C and off when the temp drops below 90 or 91C.
The fan goes into 2nd stage, or high, if the coolant temp rises above 104C, iirc.

Ecodriving goal: Drive so efficiently that the engine does not waste enough energy to heat up to 96C.

[CigaR007]

Question then becomes : which of the following has a higher penalty ? The aero drag with shutters half-open or the increased electrical load to power the Rad Fan at low speed ?

Considering the vehicle has no alternator, the engine load might not change much given that the Hybrid DC-DC converter ultimately provides the power through the small 12V battery...

Soon enough, with colder temperatures, the coolant will probably not reach 95-96C.

[CigaR007]

Considering the Electric Fan turns ON (low speed) earlier than expected (96C), I modified the logic circuit to accommodate that.

I don't know how much power the radiator fan consumes on low speed.

I think the fan circuit is on a 30A fuse.

So theoretical electrical load would be 12.6V x 30A = 378 Watts on full speed. Not sure, but Low speed could be half that, so around 190 Watts.

I would assume the aero drag would be higher than 190 Watts with shutters 50 % open.

Keeping shutters SHUT and allowing the fan to run on low speed might be more efficient, but the trade-off would be increased wear and tear on the fan motor. Which is why I considered an approach that allows a more gradual cooling.

Trigger points :

Below 90C : shutters SHUT
Above 90C : shutters open @ 25 %
Above 93C : shutters open @ 50 %
Above 96C : shutters open @ 100 %
Fans ON : shutters open @ 100 %