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Heat Driver's side only to save energy?

kr200

Member
Apr 5, 2013
33
3
Ontario Canada
I believe the Kia Soul EV can restrict heating to the driver's side to save energy and thus increase range. Would this strategy work for a Model S or would the cooler air coming in the passenger side eat up the energy savings? The Soul probably shuts off the outside air to the passenger side to achieve the energy savings. Has anyone tested this on an MS? I guess if one set the HVAC system to recirc this strategy could work but would probably result in fogging of the windows. With only the driver aboard, this might work with a regular application of windshield defrost.
Has anyone experimented with this? Results?

- - - Updated - - -

Perhaps the recirc technique would require manual selection of A/C to off? Any Tesla techies out there know how the HVAC maintains different temperature for passenger and driver?
 

AmpedUP

EV Nut
Dec 4, 2013
114
1
Herndon, VA
I was asking similar questions in Summer with regard to air conditioning. The overall response was that the energy required to propel the car forward so far outweighs other considerations as to make them not worth considering. Increase in range is obtained with slower travel speeds...and this factor is relatively exponential.
 

Cerie

Member
Sep 6, 2014
118
21
Connecticut
Alternatively, fill your passenger side with hamsters as their constant moving and furry bodies will keep you warm and toasty and use 0 energy. Sorry, I'm a sucker for those Kia hamsters :biggrin:
 

kr200

Member
Apr 5, 2013
33
3
Ontario Canada
I was asking similar questions in Summer with regard to air conditioning. The overall response was that the energy required to propel the car forward so far outweighs other considerations as to make them not worth considering. Increase in range is obtained with slower travel speeds...and this factor is relatively exponential.
That may be so with A/C which is much more efficient at transferring heat than resistance heating is for creating heat. Modern A/C can have a COP of 5 or 5x the efficiency of resistance heaters. Resistance heating, as in the MS, can thus have a very significant effect on range. I'm just trying to find a way of reducing this loss without freezing in my limited range MS40 in our Canadian winter.
It may be that the temperature of the side with the lower set temperature achieves this by adding cold air which would have the opposite effect resulting in more heat being required for the higher temperature side to compensate. Thus any temperatures that are unequal would use more power than synced temperature settings.
 
Last edited:

Johan

Ex got M3 in the divorce, waiting for EU Model Y!
Feb 9, 2012
7,473
9,545
Drammen, Norway
Would this strategy work for a Model S or would the cooler air coming in the passenger side eat up the energy savings?

Yes.

It may be that the temperature of the side with the lower set temperature achieves this by adding cold air which would have the opposite effect resulting in more heat being required for the higher temperature side to compensate. Thus any temperatures that are unequal would use more power than synced temperature settings.

Yes.


And, even it it were possible to turn off the cooling/heating on the passenger side (it is not in the Model S) you still have the whole cabin to cool/heat so unless you put up some kind of physical barrier along the midline of the car, or the driver gets in a bubble or something that's hooked up to the heating/cooling (creating a smaller volume to temperature regulate) none of this would work.

It's my absolute opinion that if you unsync the temps, no matter if you're heating or cooling, you'll use more energy.

If you want to save energy turn off AC all together and only turn it on intermittently to defog the windshield. You'll save more if you slow down 2-3 mph though.
 

kr200

Member
Apr 5, 2013
33
3
Ontario Canada
What about the case using recirc? If no cold outside air is used to reduce the passenger temperature then no energy is wasted. The overall cabin temperature can be lower if the heat is directed to the driver only. Kia obviously thinks this works to save energy.
 

Johan

Ex got M3 in the divorce, waiting for EU Model Y!
Feb 9, 2012
7,473
9,545
Drammen, Norway
What about the case using recirc? If no cold outside air is used to reduce the passenger temperature then no energy is wasted. The overall cabin temperature can be lower if the heat is directed to the driver only. Kia obviously thinks this works to save energy.

You would save a tiny bit yes. But whenever there is a large difference between interior and exterior temperature (the case where it would be possible to notice energy saving by using recirc) you would introduced the problem of humidity/fogging. In my experience this is a big problem and the only way to fix it is to turn recirc on and off intermittently and/or opening the windows intermittently, both eating up the savings. I guess if the AC could recirc but at the same time dehumidify only it may work, but it can't, and anyway the dehumidification process uses energy in itself.

If you want my honest advice, just forget the whole thing :) Not worth it.
 

ZsoZso

Supporting Member
Apr 24, 2014
1,715
9,975
Brampton, Ontario
I survived 2 winters in the GTA driving an iMiev with only 16kWh pack -- far less than your S40. My suggestion is to use as little heating as you can stand during driving and ALWAYS preheat the vehicle while plugged-in your garage before your journey starts. Then during the drive, use your seat-heater and set the air-heating to the minimum (17.5C), that will keep you comfortable while wasting as little energy for heating as possible.
 

kdid

New Member
Dec 7, 2014
4
0
The best savings would be to turn off AC, use resirc, use best choice of lowest temperature and fan speed. Then when you notice fogging, just turn on the defroster for a minute or so, to remove the fog, then turn it off again to return to previous settings. There really should had been an automatic option for that. But its easy to tap the defrost button from time to time also to archive the same effect.
 

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