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 Post subject: Vampire losses from Auto Climate Ctrl
PostPosted: Wed May 04, 2016 7:44 pm 

Joined: Sat Jun 13, 2015 1:54 pm
Posts: 244
Location: SoCal
I did a simple test today trying to assess how much energy the Climate Control uses if the outside temperature is similar to what you want the cabin temperature to be. I was concerned that leaving the Automatic Climate Control turned on all time needlessly wastes energy and range if the fan alone could work just as effectively to keep the cabin temperate.

My trip was about 30 minutes. I drove between areas with a different climate, so the starting temperature was about 78 deg and by the end it was 69 deg. The car was slightly preheated by sitting outside during today's partly cloudy day. I turned on the A/C and set it to 78 deg. The red LEDs were illuminated on both the temp dial and the mode dial. As I drove I watched the Climate Power % number. It was briefly at about 40% but within a minute or so was stable at 30%. When the outside temp got colder, I would decrease the cabin setting to match. The Climate Power % never varied beyond 29-31% during the remainder of the trip.

Based on the percentage battery consumption indication during the trip, I estimate I used just under 2.5% of the usable battery capacity on climate control. Let's call it 2.4%, which equals 0.42 kWh (17.6 kWh * 0.024) per 30 minutes of driving. That equals 0.84 kWh used per hour. If you assume an average speed of 50 mph driving for the 82 miles EPA range on the car, that would be 1.64 hrs of driving. If you take these 0.84kWh losses over 1.64 hours, that's 1.38 kWh used by the Climate Control that didn't really do anything to heat or cool the cabin. That 1.38 kWh is equivalent to about 6 miles of range.

Instead of the climate control, I could have just ventilated the cabin with the fan on a setting of 2 or 3 and would be fine. In fact, that's what I normally do. I routinely use over 80% of my battery during my commute and so on bad weather days or days that I run errands, my range gets very low. Saving 6 miles is important to me so I often go through the extra steps of adjusting the fan speed to match my desired temperature.

I haven't directly assessed how much energy the fan uses by itself, but the Climate Power % indication shows between 7-11%, so it might be a quarter to third of what the Automatic Climate Control uses when turned on.

While I don't leave the Automatic Climate Control turned on all the time, a more typical driver that doesn't use as much of the battery could indeed leave it turned on. The difference in range is probably not worth fretting over unless you're trying to extract all the range from the car.

Basically, don't worry about it unless you're going for max range. In that case use minimal climate control and manually set it.

2015 Spark EV: 2LT, DCFC, Summit White

 Post subject: Re: Vampire losses from Auto Climate Ctrl
PostPosted: Tue Jan 09, 2018 8:11 pm 

Joined: Fri Oct 13, 2017 8:41 pm
Posts: 4
Thanks for crunching the numbers!

I certainly haven't done anything nearly as scientific, however I noticed a dramatic difference in range during the summer and winter months here in the PNW.

In the summer, my usual estimated range is about 155km/96 miles, and that's about what I get driving mostly in the city with maybe 15% highway driving. That's without using climate control or a fan.
In the winter, using climate control, fan, and wipers, my usual estimated range (on the same commute) is about 94km/58 miles.

Huge difference!
I can understand why these cars aren't super popular in Canada or the midwest.
That being said, I still love my Sparky! :D

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