Yaris Hybrid aircon power use

[Mike J.]

FYI: I have been looking at Torque Pro info and there is an aircon power meter. When at full cooling mode it uses over 700W.

[mrpj]

If it consumed 7kW it wouldn't concern me, I'd rather be cool and comfortable. You would require defrosting if that were the case though. However did we cope before the advent of a/c in cars?🙄😄

[Nick B]

The 700W number is interesting.

My commute home is 15 miles and takes about 30 minutes.
I typically get 65mpg to 72mpg in moderate weather.

There is 9.6 kWh per litre of petrol.

65 mpg is
              1/65  = 0.0154 gallon per mile
              1/65 / 0.22 = 0.0699 litres per mile
              1/65 / 0.22 * 9.6 = 0.6713 kWh per mile

15 mile trip uses 15 * 0.6713 = 10.0695 kWh
30 minutes of AC at 700W = 0.35 kWh
Petrol to electric efficiency is probably about 1/3 so approximately 1kWh for AC.

This is approximately a 10% decrease in efficiency and 65 mpg goes down to 58.5 mpg if the AC is on fully. This is consistent with what I see in really hot weather.

 

[Mike J.]

Thanks for this, I was going to point out that my average mpg has been steadily dropping from 65 towards 60 in this hot weather due to such energy use and your info explains it better than I could!

[Mike J.]

On ‎8‎/‎3‎/‎2018 at 10:43 PM, Mike J. said:

….. my average mpg has been steadily dropping from 65 towards 60 in this hot weather …...

My average is now moving back to 65mpg - our cars seem to like temps around 20C.

[YarisHybrid2016]

On 8/15/2018 at 8:00 AM, Mike J. said:

My average is now moving back to 65mpg - our cars seem to like temps around 20C.

The optimum seems to be +19 C! I get some of the best economy at this temp. Warmer, and the AC eats power; cooler, and the car doesn't run so well. A nice sunny day is best when the sun is shining. I can tell you it is night time simply from the drop in fuel economy (not temperature related).

@Nick B: I noticed similar! If I run the AC at max on a hot day as we've had recently, the MPG is noticably lower until I turn the fan down. 7 (MAX) eats power; 4 is OK; 2 is great and 1 is best (OFF not being an option LOL).

[gabemc1]

It's weird how 19°C is more economical than 22° let's say. You would expect it to be the other way around. The higher the temperature, the better the fuel consumption. The AC compressor should run for shorter periods when the temperature is higher, shouldn't it? 

 

[HughA]

Not weird at all.  The higher the outside temperature the harder the air con has to work so the compressor will run for longer periods not shorter.

[gabemc1]

My bad. I thought that was the inside set temperature, not the outside.